JP2007308320A - Dielectric composition, dielectric paste composition, and dielectric obtained by using the paste composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric composition which is free from toxic lead or chromium and is capable of forming a dense fired film on a vapor-deposited aluminum electrode on a soda-lime glass substrate without foaming as a result of reaction with the electrode, to provide a dielectric paste composition, and to provide a dielectric obtained therefrom. <P>SOLUTION: Provided are a dielectric composition which is one containing a lead-free glass powder (A) and a black pigment powder (B), wherein the black pigment powder (B) is a metal oxide substantially free from cobalt, copper, and chromium; a dielectric paste composition prepared by mixing the dielectric composition with an organic vehicle (C) comprising a resin and a solvent; and a dielectric formed by applying the dielectric paste composition to the Al electrode of a display device and firing the dielectric paste composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a dielectric composition, a dielectric paste composition, and a dielectric obtained by using the dielectric composition. More specifically, the present invention relates to an aluminum vapor-deposited electrode on a soda-lime glass substrate that does not contain harmful lead and chromium. The present invention relates to a dielectric composition capable of obtaining a dense fired film without reacting and foaming, a dielectric paste composition, and a dielectric obtained using the same.

  In recent years, display devices such as a plasma display panel (hereinafter also referred to as PDP), a fluorescent display tube (hereinafter also referred to as VFD), and a field emission display (hereinafter also referred to as FED) have been developed one after another. The PDP has been widely used as a large-sized television receiver that has been spotlighted as a large-sized flat display. The VFD is used as a display device for measuring devices such as automobiles, audio equipment, and digital multimeters as a display device for characters and symbols. In addition, the FED has been expected as a display device that replaces a cathode ray tube.

The PDP is opposed to a pair of glass plates with a small gap and sealed around to provide a discharge space, and projects an image by a phosphor that emits light stimulated by ultraviolet rays generated by discharge.
The structure of the back plate of a general AC type PDP is as shown in FIG. 1, and the glass plate on the side where an image is displayed on the PDP is called the front plate, and the other is called the back plate. Striped partition walls (17) are formed on the glass substrate (10b) of the back plate, and one address electrode (15) is formed on the bottom surface of the recesses of these partition walls (17) in parallel with the partition walls. A dielectric layer (16) covering the surface of the electrode is formed. Further, a phosphor (18) excited by ultraviolet rays is applied to the wall surfaces of the partition walls.
The front plate has a transparent electrode (11) formed of striped ITO or the like and a bus electrode (12) formed of one silver or the like provided on the transparent electrode on a glass substrate (10a). Has been. A dielectric film (13) transparent to visible light made of glass or the like is formed so as to cover this electrode. An MgO film (14) is formed by vapor deposition so as to cover the dielectric film.
Here, as a method for forming the PDP, an electrode is formed by vapor deposition of aluminum or a thick film silver paste, and an existing thick film technique is used for a dielectric or a partition. In particular, the formation of electrodes by aluminum vapor deposition is frequently used unless there is a need for silver electrodes because the glass substrate is not discolored and is inexpensive.

A general VFD has a structure as shown in FIG. It has a vacuum vessel composed of a face glass (21) and a glass substrate (20), and electrons emitted from the filament (22) in the vacuum vessel are controlled by the lattice electrode (23) and collide with the segment electrode (24). Then, the phosphor on the segment electrode is stimulated to emit light to display characters, symbols, and the like. A segment electrode serving as a display portion is formed on the glass substrate, and a wiring (26) for transmitting a signal to the electrode and a dielectric insulating layer (25) for insulating the wiring from the segment electrode are disposed.
The wiring to the segment electrode is often formed with aluminum vapor deposition or thick film silver paste, the insulator covering it is formed with a dielectric paste, and the segment electrode is formed with a thick film paste mainly composed of graphite. Is done. Note that the insulating layer is printed so as to form a through-hole in order to ensure conduction between the segment electrode and the wiring. Electrode formation by aluminum vapor deposition is being frequently used like PDP.

The structure of the FED is as shown in FIG. The FED forms an emitter electrode (31) that emits electrons on one glass substrate of a vacuum vessel composed of two glass substrates (30a, 30b) facing each other, and the emitted electrons are emitted from the other glass substrate. The phosphor (33) is collided to emit stimulating light. On the glass substrate on which the electron-emitting device is formed, wiring for sending a signal to the electron-emitting device, a dielectric (35) covering the wiring, and a gate electrode (36) provided on the dielectric are formed. The emitter electrode (31) is provided at a location where no dielectric is provided. Although not shown, a columnar structure formed of a dielectric or the like is provided between two glass substrates to increase the mechanical strength of an FED vacuum vessel composed of a glass substrate or the like. There is.
Each component of the FED uses thin film technology, but the dielectric is formed by thick film technology.

In these PDP, VFD, and FED, a black dielectric may be formed to cover the electrode. The black dielectric is usually composed of a low-melting glass powder and a black pigment. The black pigment is composed of a complex oxide composed of a metal element such as chromium, cobalt, manganese or copper in order to obtain the color. As is clear from the fact that the chromium oxide contained in this pigment is represented by Cr ₂ O ₃ , the valence of the chromium atom is trivalent. On the other hand, chromium which is recently concerned about environmental problems is a valent hexavalent chromium ion. Therefore, the chromium atoms of these black pigments are not involved in environmental problems so far.

  However, when the dielectric containing these black pigments is discarded and made into acid rain or ultraviolet rays, which have become a problem in recent years, trivalent chromium ions may be oxidized to hexavalent chromium ions due to chemical changes. is there. Since the hexavalent chromium ions generated by oxidation destroy the environment, it is desirable that the black pigment does not contain chromium.

  Since a display device such as PDP uses high strain point glass (PD-200 manufactured by Asahi Glass) or soda lime glass as a substrate, the baking temperature is 600 ° C. at the highest. Therefore, if the softening point of the glass is not lower than this temperature, a dense fired film cannot be obtained. Conventional glass has realized this softening point by containing harmful substances such as lead and bismuth. However, these harmful substances contained in the conventional dielectric composition composed of glass and black pigment containing chromium are not only used when the display device is discarded as described above, but also when the display device is manufactured. Released into the environment, causing environmental problems such as pollution, pollution of soil, groundwater and rivers.

Then, the composition of the B-Si-Zn type glass which does not contain harmful substances, such as lead, is proposed (for example, refer patent documents 1-3). That is, Patent Document 1 describes a low dielectric constant glass composition having a composition such as ZnO 25 to 45%, B ₂ O ₃ 35 to 55%, and SiO _{2 5 to} 13% by weight percentage. Patent Documents 2 and ₃ disclose lead-free low-melting glass compositions whose composition is, by mass, ZnO 20 to 60%, B ₂ O ₃ 20 to 35%, SiO ₂ 5 to 45%, and the like. Glass compositions are described.

  Some of these patent documents describe aluminum electrodes, but the dielectric composition containing a black pigment does not take any measures against the occurrence of defects such as foaming in the vicinity of the aluminum vapor deposition electrode. . In other words, the composition disclosed in the above-mentioned patent document cannot be used because a dielectric failure occurs due to foamed pinholes when forming a dielectric covering the aluminum vapor deposition electrode. Therefore, it was necessary to use an expensive silver electrode as the electrode. However, when a silver electrode is used, the glass substrate is discolored and there is a microphone, which deteriorates the performance of the display device.

  Therefore, when forming a dielectric covering an aluminum vapor deposition electrode, a dielectric composition that does not cause insulation failure due to foamed pinholes, is relatively inexpensive, and does not discolor a glass substrate. The appearance of was awaited.

JP-A-9-278482 JP 2000-226231 A JP 2000-226232 A

  An object of the present invention is to provide a dielectric composition and a dielectric paste that do not contain harmful lead or chromium, and can obtain a dense fired film by reacting with an aluminum vapor deposition electrode on a soda lime glass substrate without foaming It is to propose a composition and a dielectric obtained by using the composition.

  The present inventor has solved the conventional problems, and has earnestly researched display devices such as PDPs using lead-free glass powder that does not cause environmental problems, and formulated a specific black pigment in the lead-free glass powder. By using this dielectric composition, it was found that even when this was applied to an aluminum vapor deposition electrode of a display device and fired, it did not foam and no pinholes were generated in the dielectric film, and the present invention was completed. It was.

  That is, according to the first invention of the present invention, a dielectric composition comprising a lead-free glass powder (A) and a black pigment powder (B), wherein the black pigment powder (B) comprises cobalt, copper and chromium. There is provided a dielectric composition characterized in that it is a metal oxide substantially free of.

According to the second invention of the present invention, in the first invention, the lead-free glass powder (A) does not contain bismuth, ₄ to 20 mol% of SiO ₂ in terms of oxide, and the alkali metal oxide R _2. A dielectric composition comprising 0 to 15 mol% in total of O (wherein R represents at least one alkali metal element selected from K, Na, or Li) is provided.
Further, according to the third aspect of the present invention, in a first aspect, the lead-free glass powder (A) further 15～45Mol% of _B 2 _{O 3} in terms of oxides, containing 25～50Mol% of ZnO A dielectric composition is provided.
According to a fourth aspect of the present invention, there is provided the dielectric composition according to the first aspect, wherein the black pigment powder (B) is an iron-manganese composite oxide.
Furthermore, according to the fifth invention of the present invention, in the first invention, the black pigment powder (B) is blended in an amount of 1 to 30% by mass with respect to the entire composition. Is provided.

On the other hand, according to the sixth invention of the present invention, according to any one of the first to fifth inventions, a dielectric paste composition comprising a dielectric composition and an organic vehicle (C) comprising a resin and a solvent. Things are provided.
According to a seventh aspect of the present invention, in the sixth aspect, the dielectric paste composition is characterized in that the resin content is 0.5 to 10% by mass relative to the dielectric composition. Things are provided.

On the other hand, according to the eighth invention of the present invention, there is provided a dielectric material according to the sixth or seventh invention, wherein the dielectric paste composition is formed by applying a dielectric paste composition on an Al electrode of a display device and then firing. Is done.
According to a ninth aspect of the present invention, there is provided the dielectric according to the eighth aspect, wherein the firing temperature is 540 to 580 ° C.
Furthermore, according to a tenth aspect of the present invention, there is provided the dielectric according to the eighth aspect, wherein the display device is any one of a plasma display panel, a fluorescent display tube, and a field emission display. Is done.

  ADVANTAGE OF THE INVENTION According to this invention, the dielectric material composition which covers an aluminum vapor deposition electrode without including the harmful | toxic substance of lead or chromium is realizable. Therefore, if this is used, a display device having excellent performance can be manufactured without causing pinholes near the electrodes and without changing the color of the substrate. In addition, there is no risk of environmental problems with respect to expected disposal.

  BEST MODE FOR CARRYING OUT THE INVENTION Best embodiments of the dielectric composition, the dielectric paste composition of the present invention, and the dielectric obtained using the same will be described in detail below.

1. Dielectric composition The dielectric composition of the present invention is a dielectric composition containing a lead-free glass powder (A) and a black pigment powder (B), wherein the black pigment powder (B) is cobalt, copper and chromium. It is a metal oxide which does not contain substantially.

  Although the kind of display apparatus is as above-mentioned, an aluminum vapor deposition electrode may be used for the electrode of a glass substrate by the manufacturing process. In some cases, the dielectric is formed using a black pigment containing chromium. Examples of such a black pigment include a Cr—Fe—Co composite oxide, a Cu—Cr—Mn composite oxide, and a Cu—Cr—Fe composite oxide. However, after forming the electrode by such aluminum vapor deposition, the aluminum vapor deposition electrode forms a thick film paste of a dielectric composition composed of a black pigment containing either chromium, cobalt or copper and glass containing no lead. When printed on a printed substrate and fired, the dielectric composition and the electrode may react during firing to cause pinholes in the fired film of the dielectric composition, resulting in poor electrical insulation. This pinhole is considered to be due to the occurrence of an oxidation-reduction reaction due to an aluminum vapor deposition electrode, the thermite reaction of pigment or glass.

  However, such a reaction does not occur and pinholes do not occur in a dielectric composition in which a black pigment containing any one of chromium, cobalt, and copper and a glass containing lead are combined. The reason why the reaction with the aluminum vapor deposition electrode does not occur when the dielectric is formed of such a composition has not been clarified so far. However, since it does not occur when glass containing lead is used, it seems that the composition of glass containing no lead has an effect.

(A) Lead-free glass powder In the dielectric composition of the present invention, the glass powder must be substantially free of lead. In the present invention, the glass transition point of the lead-free glass powder (hereinafter also referred to as glass composition) is 430 to 540 ° C.

  As described above, in a display device such as a PDP using a glass substrate, the glass composition is usually fired at a temperature of 600 ° C. or lower. Therefore, it is necessary to suppress the softening point of the glass composition to 600 ° C. or lower. As a result, the glass transition point of the glass composition having a softening point of 600 ° C. is necessarily 540 ° C. or lower. On the other hand, the glass transition point of 430 ° C. or higher is due to the sealing process of these display devices. In these display devices, a vacuum container is formed by bonding and sealing two glass substrates and the like. In this sealing process, the sealing material is softened and fired at around 430 ° C. When the glass transition point is lower than this temperature in the glass composition of the present invention, the partition walls and dielectric formed in the sealing process are softened. Therefore, it becomes impossible to ensure the dimensional accuracy of the display device. Therefore, if the sealing temperature is lower than 430 ° C., a glass composition having a low glass transition point is adopted accordingly. The glass transition point can be measured by TG-DTA or TMA.

In the glass composition, SiO ₂ is an essential component and a glass network former. The content of SiO ₂ is 4 to ₂₀ mol% in terms of oxide. If it is less than 4 mol%, the water resistance and chemical resistance of the glass are poor, and if it exceeds 20 mol%, the softening point becomes high.
In addition, although the reason is unknown, a dielectric composition comprising a glass having a desired glass transition point or softening point and containing 20 mol% or more of SiO ₂ and a black pigment containing neither chromium, cobalt, nor copper is obtained by firing. It may react with the aluminum vapor deposition electrode to generate pinholes. Since the frequency of occurrence of pinholes is low, it can be repaired by printing a dielectric paste on the fired dielectric, drying, and firing.
However, a dielectric composition composed of a glass having a desired glass transition point and softening point and containing 20 mol% or more of SiO ₂ and a black pigment containing any one of chromium, cobalt, and copper reacts with the aluminum vapor deposition electrode by firing to produce a large number. As a result, a pinhole is formed, which is not practical.

B ₂ O ₃ in the glass is an essential component, and has the effect of lowering the softening point and increasing fluidity and stabilizing the glass. It is an essential requirement that the content of B ₂ O ₃ be 15 to 45 mol%. If it is less than 15 mol%, the softening point becomes high and a desired value cannot be realized, and if it exceeds 45 mol%, the softening point becomes low and the desired value cannot be realized and the water resistance and chemical resistance of the glass are inferior. More desirably, it is 43 mol% or less.

  ZnO in the glass is an essential component, and has the effect of lowering the softening point and adjusting the thermal expansion coefficient appropriately. ZnO is adjusted to 25 to 50 mol% in terms of oxide. If it is less than 25 mol%, the desired softening point cannot be realized, and if it exceeds 50 mol%, vitrification is difficult.

Alkali metal oxide R ₂ O (wherein R represents at least one alkali metal element selected from K, Na, or Li) is a constituent of glass. These lower the softening point and increase the coefficient of thermal expansion. R ₂ O is to contain 5 to 15 mol% in terms of oxide. If it is less than 5 mol%, the softening point becomes too high to obtain a desired value, and it is desirably 7 to 13 mol%. If R ₂ O is contained in an amount exceeding 15 mol%, it is not desirable because it increases the thermal expansion coefficient. R 2 _O is conducted as R ⁺ ions in the glass and adversely affect the electrical insulating properties. Also from this viewpoint, the content of R ₂ O is defined.

BaO has an effect of lowering the softening point of the glass, and can be added up to 35 mol%. BaO has the effect of increasing the coefficient of thermal expansion, and the addition amount described above is desirable from this viewpoint.
In addition, CaO and SrO can be added as appropriate. CaO and SrO have the effect of stabilizing the glass. However, these have the effect of increasing the coefficient of thermal expansion. Therefore, if they are contained excessively, the coefficient of thermal expansion becomes large and it becomes inappropriate for using soda lime glass or the like as a substrate. Therefore, the blending amount of CaO and SrO is desirably 35 mol% or less.

ZrO ₂ is not an essential component of glass, but has an effect of improving water resistance and chemical resistance. ZrO ₂ is made to be 15 mol% or less in terms of oxide. If it exceeds 15 mol%, the softening point of the glass is raised and the desired value cannot be realized. Al ₂ O ₃ is not an essential component of glass, but has an effect of improving water resistance and chemical resistance by preventing glass from phase separation. Al ₂ O ₃ is made to be 15 mol% or less in terms of oxide. If it exceeds 15 mol%, the softening point becomes high and a desired value cannot be realized.

The particle size of the glass powder is preferably 10 μm or less, and more preferably 5 μm or less in terms of D ₅₀ (cumulative particle size distribution and median value of particle size). If it is larger than this, a dense dielectric cannot be obtained. In order to obtain a powder having a desired particle size, a known grinding method such as a ball mill or a jet mill can be used.

(B) Black pigment powder The dielectric composition of the present invention is characterized in that the black pigment is a metal oxide that substantially does not contain any of chromium, cobalt, and copper. Note that “substantially not contained” means that it may be contained as long as it is inevitable in production.

  Up to now, conductive materials such as ruthenium oxide, titanium black, or carbon black have been known as black pigments. However, since they are conductive, they are not suitable for dielectrics that insulate electrodes.

  On the other hand, black pigments that are not conductive include alloy oxides of iron and one or more selected from chromium, cobalt, copper, manganese, and the like, which are put into practical use as dielectric compositions for display devices. In the present invention, it is important to use a black pigment that does not contain any of chromium, cobalt, and copper. As such a black pigment, for example, there is an Fe—Mn composite oxide. If it becomes black, the ratio of Fe and Mn is not particularly limited.

Specific examples of the Fe—Mn composite oxide include an Fe—Mn composite oxide and an Fe—Mn—Al composite oxide. In addition to Al, elements such as Ni and Si can be included as long as the object of the present invention is not impaired. Although content in particular of Al etc. is not restrict | limited, It is 30 mass% or less with respect to Fe-Mn complex oxide, Preferably it is 20 mass% or less, More preferably, it is 10 mass% or less. The particle size _{D 50} of the black pigment is 5μm or less. When the particle size D ₅₀ exceeds 5 μm, there arises a problem that the surface roughness of the dielectric becomes rough.

On the other hand, for example, Cr—Fe—Co composite oxide, Ni—Cr—Fe—Co composite oxide, Ni—Cr—Al—Fe—Co composite oxide, Al—Cr—Fe—Mn—Co— Black pigments containing chromium such as Si composite oxide, Cu-Cr-Mn composite oxide, Cu-Cr composite oxide, Cu-Cr-Fe composite oxide react with aluminum vapor deposition electrodes on soda lime glass substrates. Thus, a dense fired film cannot be obtained.
In addition, black pigments containing cobalt and copper include, for example, Fe—Cu—Mn composite oxide, Cu—Cr—Mn composite oxide, Cu—Cr—Fe composite oxide, Ni—Mn—Fe—. Co composite oxide, Mn—Fe—Co composite oxide, Al—Mn—Fe—Co composite oxide, Fe—Cu—Mn composite oxide, Ni—Mn—Fe composite oxide, Ni—Mn—Fe— Although there are Co composite oxides and the like, it reacts with the aluminum vapor deposition electrode on the soda lime glass substrate and foams similarly, and a dense fired film cannot be obtained.

The dielectric composition of the present invention is prepared by blending 70 to 99% by mass of lead-free glass powder and 30 to 1% by mass of black pigment powder. If the glass powder containing no lead is less than 70% by mass, the glass is too little to obtain a dense fired film. On the other hand, if the glass powder containing no lead is more than 99% by mass, the pigment is too little to obtain the desired black color.
If the black pigment powder is less than 1% by mass, the desired black color cannot be obtained. If the black pigment powder is contained in an amount of more than 30% by mass, the glass is too small to obtain a dense fired film. Preferred blending ratios are 80 to 98% by mass of glass powder containing no lead and 20 to 2% by mass of black pigment powder, 90 to 97% by mass of glass powder not containing lead, and 10 to 3% of black pigment powder. %.

2. Dielectric Paste Composition The dielectric paste composition of the present invention is composed of an inorganic component such as glass powder and black pigment powder and an organic vehicle. The organic vehicle consists of a resin and an organic solvent described later.
Here, the inorganic component is composed of the glass composition and inorganic oxides such as alumina, silica, forsterite, zirconia, zircon, and titanium oxide added to the glass composition as necessary. The inorganic oxide is not limited to selection of only one type, and a plurality of types can be combined.

The thermal expansion coefficient of the dielectric paste composition is determined by the glass powder and the inorganic oxide. The thermal expansion coefficient is desirably in the range of 50 to 87 × 10 ⁻⁷ . The thermal expansion coefficient of a substrate such as soda lime glass is 83 to 87 × 10 ⁻⁷ , and if it is not less than this value, the device warps during firing. The thermal expansion coefficient can be controlled by a combination of glass powder and inorganic oxide. Among silicas, quartz glass has a thermal expansion coefficient of 55 × 10 ⁻⁷ and has an effect of lowering the thermal expansion coefficient. Forsterite has a thermal expansion coefficient of 95 × 10 ⁻⁷ and has an effect of increasing the thermal expansion coefficient. There is.

  Silica (quartz) is known to undergo phase transition, and when it undergoes phase transition to cristobalite or the like, the thermal expansion coefficient changes rapidly. Cracks may occur in the partition walls and the dielectric due to a sudden change in thermal expansion coefficient. In order to prevent such a situation, quartz glass powder can be used. Quartz glass powder can exhibit the same effect as the inorganic oxide in the present invention.

(C) Organic vehicle In this invention, an organic vehicle is comprised from resin and an organic solvent. The resin is a component necessary for maintaining the viscosity of the paste, maintaining the shape after coating and drying, and improving the chemical resistance of the dried film. An appropriate resin amount is 0.5 to 20% by mass, preferably 0.5 to 15% by mass with respect to 100% by mass of the dielectric composition. If it is less than 0.5% by mass, it is difficult to maintain the shape after coating and drying, the lead-free glass powder and black pigment of the paste are liable to settle, the life of the paste is shortened, and printability and coatability are impaired. As a result, the practical use of the paste is hindered. If it exceeds 20% by mass, it may not be removed after firing, which is not preferable.

  The resin used for the vehicle needs to be decomposed or burned in the baking process and completely removed. The resin is required to be removed at a firing temperature below the softening point of the glass composition. This is because a resin that burns at a temperature equal to or higher than the softening point is trapped in a softened glass film and generates many voids such as bubbles.

  Examples of the resin that decomposes or burns at such temperatures include ethyl cellulose, acrylic, polyvinyl butyral, and methylstyrene. Acrylic includes methacrylic resin. These resins have the same effect regardless of whether they are used alone or a plurality of types are mixed.

An organic solvent in the vehicle is an essential component for improving the fluidity of the paste. Therefore, the solvent is blended in an amount of 20 to 45% by mass with respect to 100% by mass of the dielectric composition. When the amount of the solvent is less than 20% by mass, it is difficult to form a paste.
The solvent must dissolve the resin and must volatilize during the drying process. If importance is attached only to volatility and a solvent having a boiling point of less than 150 ° C. is selected, the paste dries in the coating process, resulting in poor workability.

  From this point of view, the boiling point of the solvent is desirably 150 ° C. or higher. From the solubility of the resin, terpinol, dihydroterpinol, butyl carbitol acetate, butyl carbitol, 2,2,4-trimethyl-1,3-pentanediol mono Butyrate, octyl alcohol and the like are selected.

  Known additives such as antifoaming agents, dispersants, and plasticizers can be added to the paste as thick film pastes. Further, a photosensitive agent that is cured by ultraviolet rays can be added to bring the paste to photosensitivity. In the present invention, the additive may be added after being previously mixed with a powder mixture or vehicle of glass powder and inorganic powder, or may be added directly to the dielectric paste as it is. The dielectric paste composition can be manufactured using a known method such as a roll mill or a ball mill.

3. Dielectric The above dielectric paste composition of the present invention can be printed and applied to an electrode on a display device substrate, and then fired at a predetermined temperature to obtain a dielectric. This dielectric can be applied to any display device such as a plasma display panel, a fluorescent display tube, or a field emission display.

Printing or application of the dielectric paste composition (hereinafter also referred to as dielectric paste) to the substrate can be performed by a known method such as screen printing, applicator, doctor blade, die coater, or the like.
The pattern formation of the dielectric paste can be performed by a known method such as screen printing, sandblasting or embedding in a photoresist. In a display device such as a PDP, since a high strain point glass or soda lime glass such as PD-200 made by Asahi Glass is used for the substrate, the baking temperature must be 600 ° C. at the highest.

  In the present invention, the firing temperature is desirably 540 to 580 ° C. Since high strain point glass or soda lime glass is used for the substrate as described above, the firing temperature is 600 ° C. at the highest, and it is desirable to fire the dimensional accuracy due to deformation of the substrate at a lower firing temperature. Therefore, the upper limit of the firing temperature is 580 ° C., and more preferably the upper limit is 570 ° C. On the other hand, the lower limit of the firing temperature is determined by the relationship between the sealing temperature of PDP or the like and the glass transition point of the lead-free glass powder used for the dielectric. In a general sealing process such as PDP, a sealing material mainly composed of lead glass is melted and sealed at a temperature around 450 ° C. Since the dielectric does not deform by heating to 450 ° C. in the sealing process, the glass transition point of the dielectric lead-free glass must be higher than the sealing temperature, and the lower limit of the firing temperature of such glass This is because the temperature is 540 ° C. In the present invention, lead-free glass powder is used, but since a specific black pigment is blended in the dielectric composition, no pinhole is formed after being applied and fired on the aluminum vapor-deposited electrode.

  Examples of the present invention and comparative examples are shown below, but the present invention is not limited to these examples.

(Evaluation of foamability of aluminum evaporated electrode)
The foamability was evaluated by visually confirming foaming of the fired film of the dielectric composition formed on the electrode after printing and firing the dielectric paste so as to cover the electrode of the glass substrate. When there was no foaming per 1 cm ^{2 of the} electrode area, it was evaluated as ◯, and when there was even one, it was evaluated as x.

(Examples 1-4)
First, the glass powder which is a component of the dielectric composition of this invention was prepared. Glasses having the compositions shown in Table 1 were melted at 1300 ° C., rapidly cooled, and pulverized with a ball mill. The particle size of the obtained glass powder was measured with a microtrack, and the glass transition point and the softening point were measured with TG-DTA (TG / DTA320 type manufactured by Seiko Denshi). Table 1 shows the particle size of the obtained glass powder.
Next, 92% by mass of glass powder and 8% by mass of black pigment powder were blended, 40% by mass of vehicle was added to 100% by mass of the dielectric composition, and mixed with a roll mill to obtain a dielectric paste. As the black pigment, an Fe—Mn oxide (Mn compound: 33% by mass as Mn, particle size D ₅₀ : 2.8 μm) was used.
The vehicle was obtained by mixing 10% by mass of ethyl cellulose (molecular weight 80000) in a resin and 90% by mass of terpinol in a solvent, and heating to 60 ° C. to obtain a vehicle.
The electrode was formed by a known method in the manufacturing process of the display device, and aluminum was deposited on the soda lime glass substrate to a thickness of 1 μm. The electrode was vapor-deposited through a metal mask to form a pattern shape in which the electrode was formed only at the mask opening.
Dielectric paste was printed and fired on the glass substrate on which the electrode was formed so as to cover the electrode, and foaming of the fired film of the dielectric composition on the electrode was visually confirmed. In the case of Example 4, foaming did not occur, but it was confirmed that foaming occurred when the blending amount of the glass powder was increased to 95% by mass.

(Comparative Examples 1-11)
An experiment was conducted in the same manner as in Example 1 except that a glass powder containing lead was used (Comparative Example 1). Moreover, it experimented like the said Example 1 except having used the thing containing copper and chromium as a black pigment (Comparative Examples 2-6). This black pigment is a Cu—Cr—Mn oxide (Cu compound: 25 mass% as Cu, Cr compound: 43 mass% as Cr, Mn: 3 mass%, particle size D50: 1.8 μm).
Furthermore, it experimented like the said Example 1 except having used the thing containing chromium and cobalt as a black pigment (Comparative Examples 7-11). The black pigment is a Cr—Fe—Co-based oxide (Cr compound: 29 mass% as Cr, Co compound: 23 mass% as Co, particle size D ₅₀ : 1.5 μm).

It is explanatory drawing which shows the structure of a general PDP. It is explanatory drawing which shows the structure of general VFD. It is explanatory drawing which shows the structure of a general FED.

Explanation of symbols

10a, 10b Glass substrate 11 Transparent electrode 12 Bus electrodes 13, 16 Dielectric 14 MgO film 15 Address electrode 17 Partition 18 Phosphor 20 Glass substrate 21 Face glass 22 Filament 23 Grid electrode 24 Segment electrode 25 Dielectric 26 Wiring 27 Terminal 30a, 30b Glass substrate 31 Emitter electrode 32 Anode 33 Phosphor 34 Cathode electrode 35 Dielectric 36 Gate electrode 37 Spacer

Claims (10)

  A dielectric composition comprising a lead-free glass powder (A) and a black pigment powder (B), wherein the black pigment powder (B) is a metal oxide substantially free of cobalt, copper and chromium. A dielectric composition. The lead-free glass powder (A) does not contain bismuth, ₄ to 20 mol% of SiO ₂ in terms of oxide, and an alkali metal oxide R ₂ O (wherein R is at least one selected from K, Na, or Li) 2. The dielectric composition according to claim 1, wherein 0 to 15 mol% in total is represented. The dielectric composition according to claim 1, wherein the lead-free glass powder (A) further contains 15 to 45 mol% of B ₂ O ₃ and 25 to 50 mol% of ZnO in terms of oxide.   The dielectric composition according to claim 1, wherein the black pigment powder (B) is an iron-manganese composite oxide.   The dielectric composition according to claim 1, wherein the black pigment powder (B) is blended in an amount of 1 to 30% by mass with respect to the entire composition.   A dielectric paste composition comprising the dielectric composition according to any one of claims 1 to 5 and an organic vehicle (C) comprising a resin and a solvent.   The dielectric paste composition according to claim 6, wherein the resin content is 0.5 to 10% by mass with respect to the dielectric composition.   A dielectric formed by applying the dielectric paste composition according to claim 6 or 7 on an Al electrode of a display device and then firing the applied paste.   The dielectric according to claim 8, wherein the firing temperature is 540 to 580 ° C.   9. The dielectric according to claim 8, wherein the display device is any one of a plasma display panel, a fluorescent display tube, and a field emission display.

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