JP2007280730A - Manufacturing method of plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a plasma display panel wherein the panel can be suitably manufactured and its display characteristics can be enhanced. <P>SOLUTION: In the forming process of a crystal MgO layer 342, a coating liquid obtained by dispersing MgO powder 342A in a solvent is applied on the a thin film MgO layer 341. A dispersing agent having viscosity higher than that of the solvent is added to the coating liquid. Since the dispersing agent functions as an adhesive for MgO and the surface of a substrate, adhesion efficiency of the MgO powder to the substrate can be enhanced. Dispersiblity of the MgO powder on the substrate can be enhanced, and the amount of the coating liquid used can be reduced. The MgO powder is prevented from being dried and coagulated on the substrate after coating. Since the crystal MgO layer 342 can be uniformly formed, display characteristics of the PDP can be enhanced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a plasma display panel in which a protective layer of the plasma display panel is formed by a spray method.

A plasma display panel (PDP) is a device that displays an image using light emission by plasma discharge, and is a pair of flat glass substrates that are opposed to each other through a discharge space. It has.
On the inner surface side of such a front substrate, a plurality of display electrodes consisting of a plurality of transparent electrodes and bus electrodes laminated on one end of these transparent electrodes, and a plurality of black stripes provided between these display electrodes, A dielectric layer covering the display electrode pairs and the black stripe, a protective layer covering the dielectric layer, and the like are provided.

  The protective layer functions as a secondary electron emission layer for preventing the dielectric layer from being sputtered by discharge and generating discharge at a low voltage. The protective layer is required to have light transmissivity that allows visible light to pass through because light emission in the discharge cell is observed from the front substrate side through the protective layer. For this reason, as a material for the protective layer, magnesium oxide (hereinafter referred to as MgO) having characteristics such as a low sputtering rate, a high secondary electron emission coefficient, and visible light transmittance is widely used. In particular, single crystal MgO is suitable as a material for the protective layer because it has the effect of further increasing the discharge probability.

Conventionally, as a method for forming such a protective layer, a method in which a coating liquid in which a fine crystal powder of MgO is dispersed in a solvent is applied on a substrate by a spray method using a spray gun is known (for example, Patent Document 1).
In the configuration described in Patent Document 1, a suspension for spraying is obtained by dispersing a microcrystalline powder of MgO having a diameter of 1 to 2 μm using ethanol as a dispersion solvent. Then, the suspension and high-pressure air for atomization are supplied to the spray gun, and the suspension is spray-coated on the glass substrate. Then, the glass substrate is heated to 200 ° C. to sufficiently evaporate ethanol, and MgO fine A configuration is adopted in which an MgO film in which crystals are stacked is obtained.

  Here, when the MgO film is formed by the spray method as in the configuration described in Patent Document 1, in the completed PDP, if the MgO powder is not deposited with a sufficient thickness as a protective layer, a discharge delay occurs. There is a risk of causing characteristic failure such as selection failure. In addition, when variations occur in the amount of MgO powder applied, characteristic defects such as uneven brightness, variations in discharge probability, and scan defects are caused. Therefore, in forming the MgO film by the spray method, it is necessary to deposit the MgO powder with a sufficient thickness and disperse the MgO powder on the substrate as uniformly as possible.

  Here, in order to uniformly disperse the MgO powder on the substrate, it is effective to make the droplets small when the coating liquid is atomized. Such micronization of droplets can be achieved by increasing the atomizing air pressure, increasing the discharge pressure of the coating liquid from the spray gun, or the like.

JP-A-7-296718

  However, if the air pressure for atomization or the discharge pressure of the coating liquid is increased, the spray speed of the coating liquid increases, so that the mist-like coating liquid is reflected on the substrate surface, and the mist-like coating liquid is reflected. The working fluid will soar. For this reason, the adhesion efficiency of the coating liquid to the substrate decreases, and the amount of the coating liquid to be used increases when forming the MgO film having a predetermined thickness. As a result, there is a problem that the manufacturing cost of the PDP increases. In addition, as the mist-like coating liquid rises, the frequency of cleaning particle traps such as bag filters placed in the spray booth and spray chamber of the coating apparatus and the inner wall of the apparatus increases. There is a problem that the cost required for maintenance of the coating apparatus also increases.

  Here, a method of increasing the viscosity of the solvent in the coating liquid to improve the coating efficiency of the coating liquid to the substrate is also conceivable. However, increasing the viscosity of the solvent increases the boiling point of the solvent, thereby It becomes difficult to dry the substrate after processing at room temperature. In addition, when the substrate after coating is dried, the MgO powder aggregates in an island shape due to the surface tension of the solvent, which may cause a problem that the MgO powder cannot be uniformly dispersed on the substrate.

  In view of the above-described problems, it is an object of the present invention to provide a method for manufacturing a plasma display panel that can be preferably manufactured and display characteristics of the panel can be improved.

  According to the first aspect of the present invention, a pair of substrates opposed to each other through a discharge space, a plurality of electrode pairs formed on the inner surface of one of the pair of substrates, and the electrode pairs A method of manufacturing a plasma display panel comprising a dielectric layer to be coated and a protective layer covering the dielectric layer, wherein the protective layer forming step for forming the protective layer includes a spray gun using a spray gun. And a step of applying a coating liquid in which magnesium oxide powder is dispersed in a solvent by a method, and a plasma having a viscosity higher than that of the solvent is added to the coating liquid. A display panel manufacturing method.

In the present invention, by adding a dispersant having a viscosity higher than that of the solvent to the coating liquid, the coating efficiency of the coating liquid to the substrate can be improved, and the MgO powder can be uniformly dispersed on the substrate. It was devised based on.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing an internal structure of a plasma display panel according to an embodiment of the present invention. FIG. 2 is a front view schematically showing the plasma display panel. 3 is a side sectional view taken along line III-III in FIG. 4 is a side sectional view taken along line IV-IV in FIG.

(1) Configuration of Plasma Display Panel In FIG. 1, reference numeral 1 denotes a plasma display panel (PDP). This PDP 1 is formed in, for example, a substantially planar rectangular shape, and displays an image using light emission by plasma discharge. It is a device to display. The PDP 1 includes a back substrate 2 and a front substrate 3 that are arranged to face each other via a discharge space H that forms an image display area.
The back substrate 2 and the front substrate 3 are sealed by providing seal frits (not shown) at their outer peripheral edges. The sealed space is in a reduced pressure state of, for example, about 6.7 × 104 Pa (500 Torr), and the space is He—Xe (helium-xenon) or Ne—Xe (neon-xenon). Filled with inert gas.

  The back substrate 2 is formed in a planar rectangular shape with, for example, a sheet glass material. As shown in FIG. 1, a plurality of linear address electrodes 21, an address electrode protection layer 22 covering the address electrodes 21, and the address electrode protection layer 22 are integrated on the inner surface of the rear substrate 2. The barrier ribs 23 provided in this manner and the phosphor layers (24R, 24G, 24B) filled in the discharge cells 231 of the barrier ribs 23 are provided.

  Specifically, the address electrodes 21 are made of, for example, Al (aluminum) or the like, and are arranged at regular intervals substantially orthogonal to the longitudinal direction of the back substrate 2 as shown in FIG. An address electrode lead portion (not shown) is formed at one end of each address electrode 21, and a voltage pulse from a column electrode driving portion (not shown) is applied to each address electrode 21 via the address electrode lead portion. ing.

  The address electrode protective layer 22 is formed of, for example, glass paste, and is provided over substantially the entire surface excluding the address electrode lead portion on the inner surface of the back substrate 2 as shown in FIGS. The address electrode protective layer 22 functions as a dielectric layer for preventing the wear of the address electrode 21 due to discharge and accumulating charges necessary for driving during panel driving. The above-described seal frit is provided on the outer peripheral edge portion of the address electrode protection layer 22.

  As shown in FIGS. 1 and 3, the partition wall 23 is formed, for example, in a substantially ladder shape with a glass paste having the same component as that of the address electrode protection layer 22. On the address electrode protective layer 22, a plurality of linear gaps S (see FIG. 3) that are substantially orthogonal to the address electrodes 21 are provided in parallel with each other. The partition wall 23 divides the discharge space H into a plurality of sections, thereby forming a plurality of rectangular discharge cells 231. The partition wall 23 is set to have a predetermined height dimension from the base end portion to the top portion, and defines the gap dimension between the back substrate 2 and the front substrate 3.

  As shown in FIGS. 1, 3 and 4, the phosphor layers (24R, 24G, 24B) have red (R), green (G), and blue (B) phosphor pastes in order inside the discharge cell 231. It is formed by filling and firing. These phosphor layers (24R, 24G, 24B) are excited by ultraviolet light generated in the respective discharge cells 231 and emit visible light of three primary colors of red (R), green (G), and blue (B). .

  The front substrate 3 constitutes the display surface of the PDP 1 and is formed, for example, in substantially the same shape with the same material as the rear substrate 2. On the inner surface of the front substrate, as shown in FIG. 1, a plurality of display electrode pairs 31 that are substantially orthogonal to the address electrodes 21 and arranged at regular intervals are provided between the display electrode pairs 31. A plurality of black stripes 32, a dielectric layer 33 covering the display electrode pairs 31 and the black stripes 32, a protective layer 34 covering the dielectric layer 33, and the like are provided.

  Specifically, as shown in FIGS. 2 and 3, the display electrode pair 31 includes a plurality of pairs of transparent electrodes 311a and 311b facing each other via a discharge gap G (see FIG. 2), and the transparent electrodes 311a and 311b. It comprises a pair of linear bus electrodes 312a and 312b stacked on one end.

  As shown in FIG. 2, the transparent electrodes 311 a and 311 b are formed in a substantially T shape with a transparent conductive film such as ITO (Indium Tin Oxide), and are provided in pairs corresponding to predetermined discharge cells 231. Yes.

The bus electrodes 312a and 312b are provided to be stacked on the opposite ends of the pair of transparent electrodes 311a and 311b with respect to the discharge gap G (see FIG. 2). A bus electrode lead portion (not shown) is formed at one end of each of the bus electrodes 312a and 312b, and a voltage pulse from a row electrode driving portion (not shown) is applied to each of the transparent electrodes 311a and 311b via the bus electrode lead portion. It has become so.
As shown in FIG. 3, the bus electrodes 312 a and 312 b have bus electrode black layers 313 a and 313 b made of a black inorganic pigment provided on the transparent electrodes 311 a and 311 b and the bus electrode black layers. It has a two-layer structure including main conductive layers 314a and 314b made of a metal material mainly composed of Ag (silver) or the like provided by being laminated on 313a and 313b.

  As shown in FIGS. 2 and 3, the black stripe 32 is formed linearly with the same material as the bus electrode black layers 313a and 313b. Visible light irradiated from the outside of the front substrate 3 is absorbed by the black stripe 32 and the bus electrode black layers 313a and 313b.

  As shown in FIGS. 1 and 3, the dielectric layer 33 is formed of, for example, glass paste or the like, and is provided to face the address electrode protection layer 22 of the back substrate 2. This dielectric layer 33 prevents wear of the display electrode pair 31 due to discharge during panel driving, and accumulates charges necessary for driving.

As shown in FIGS. 1, 3 and 4, the protective layer 34 covers a thin film MgO layer 341 made of MgO (magnesium oxide) covering the entire inner peripheral surface of the dielectric layer 33 and the thin film MgO layer 341. A two-layer structure including a crystalline MgO layer 342 is formed.
The thin film MgO layer 341 is formed by, for example, vapor deposition or sputtering. The crystalline MgO layer 342 is formed by a spray method described later.
The protective layer 34 functions as a secondary electron emission layer for preventing the dielectric layer 33 from being sputtered by discharge and generating discharge at a low voltage.

(2) Schematic Configuration of Manufacturing Method of PDP 1 Next, a schematic configuration of the manufacturing method of the PDP 1 having the above configuration will be described with reference to the drawings. FIG. 5 is a schematic view showing a process of forming a single crystal MgO powder layer by a spray method.

First, in the production line of the back substrate 2 of the PDP 1, the inner surface side of the glass substrate is sufficiently washed by ultrasonic washing treatment or water washing treatment using a neutral detergent.
Thereafter, a metal thin film is formed on the entire inner surface of the glass substrate, and a pattern of the address electrode 21 is formed by photolithography.
A glass paste is applied onto the address electrode 21, and the address paste protective layer 22 and the partition wall 23 are formed by molding and baking the glass paste.
Then, phosphor pastes of the three primary colors of red (R), green (G), and blue (B) are applied to the inside of the discharge cell 231 by screen printing or the like, and this is fired to obtain phosphor layers (24R, 24G, 24B).
Thus, the back substrate 2 of the PDP 1 is completed.

Next, in the production line for the front substrate 3 of the PDP 1, the inner surface side of the glass substrate is sufficiently washed by ultrasonic washing treatment, water washing treatment using a neutral detergent, or the like.
Thereafter, a transparent electrode material layer is formed on the entire inner surface of the glass substrate, and a plurality of transparent electrodes 311a and 311b are formed by a photolithography method or the like. A paste pattern of black inorganic pigment is laminated on the transparent electrode pair by screen printing or the like, and an Ag paste pattern is further laminated on the pattern. Then, these patterns are fired to form bus electrodes 312a and 312b having a two-layer structure including bus electrode black layers 313a and 313b and main conductive layers 314a and 314b.
Thereafter, a paste pattern of black inorganic pigment is applied between the bus electrodes 312a and 312b by a screen printing method or the like, and this is fired to form a plurality of black stripes 32.
Further, a dielectric layer 33 is formed by applying glass paste with a die coater or the like so as to cover the transparent electrodes 311a and 311b, the bus electrodes 312a and 312b, and the black stripes 32.

Thereafter, a thin film MgO layer 341 is formed on the dielectric layer 33 by vapor deposition or sputtering.
Further, as shown in FIG. 5, a coating solution in which the single crystal MgO powder 342A is dispersed in a solvent is spray-coated on the thin film MgO layer 341 by a spray method, and this is fired to form a crystalline MgO layer 342. (Crystal MgO layer 342 formation step). In the spray method in the present embodiment, coating apparatuses 800 and 900 shown in FIGS. 6 and 7 are used, and various atomization methods shown below can be adopted. Moreover, what mixed the MgO powder shown below, a solvent, and a dispersing agent is used for a coating liquid.
Thus, the front substrate 3 of the PDP 1 is completed.

(3) Structure of coating apparatus The coating apparatus which forms the above-mentioned crystalline MgO layer 342 by a spray method is demonstrated based on FIG. FIG. 6 is a schematic diagram showing the first coating apparatus. FIG. 7 is a schematic view showing a second coating apparatus.

As shown in FIG. 6, the first coating apparatus 800 includes a coating liquid tank 810 that stores a coating liquid LQ in which single-crystal MgO powder is dispersed in a solvent, and a pipe 811 connected to the coating liquid tank 810. And a spray gun 830 connected to the liquid feed pump 820 via a pipe 821.
Such a first coating apparatus 800 sucks the coating liquid LQ in the coating liquid tank 810 with the liquid feed pump 820 and moves the spray gun 830 above the front substrate 3 while spray gun 830. Accordingly, the coating liquid LQ is discharged onto the coating surface of the front substrate 3.
In the first coating apparatus 800, only when spray coating is performed, the liquid feed pump 820 is driven to supply the coating liquid LQ to the spray gun 830.

As shown in FIG. 7, the second coating apparatus 900 includes a coating liquid tank 910 that stores a coating liquid LQ in which single-crystal MgO powder is dispersed in a solvent, and a pipe 911 in the coating liquid tank 910. A three-way valve 930 connected to the liquid feeding pump 920 via a pipe 921 and connected to the inside of the coating liquid tank 910 via a pipe 931, and the three-way valve 930. A spray gun 940 connected to the valve 930 via a pipe 932 is provided.
In such a second coating apparatus 900, the liquid feed pump 920 is always driven, and only when spray coating is performed, the three-way valve 930 is switched to the spray gun 940 side and the inside of the coating liquid tank 910 is changed. The coating liquid LQ is supplied to the spray gun 940. Then, while moving the spray gun 940 above the front substrate 3, the coating liquid LQ is discharged from the spray gun 940 onto the coating surface of the front substrate 3.
On the other hand, while the spray application is not performed, the coating liquid LQ is circulated in order of the coating liquid tank 910, the pipe 911, the liquid feed pump 920, the pipe 921, the three-way valve 930, the pipe 932, and the coating liquid tank 910. In this way, the coating liquid LQ is constantly circulated regardless of whether or not spray coating is performed, thereby preventing the single crystal MgO powder from settling in each part of the apparatus.

(4) Atomization method When spray coating is performed using the coating apparatuses 800 and 900 shown in FIGS. 6 and 7, the coating liquid is atomized and spray-coated on the substrate. In the present embodiment, a one-fluid atomization method, a two-fluid atomization method, a bell method, or the like can be adopted for the atomization of the coating liquid.

In the one-fluid atomization system, a pressure is applied to the coating liquid, and the coating liquid is made into a mist using a shearing force at the time of jetting. That is, for example, pressure is applied to the coating liquid LQ discharged from the spray guns 830 and 940 from the liquid feed pumps 820 and 920 shown in FIGS. 6 and 7 to atomize the coating liquid LQ.
In such a one-fluid atomization system, the particle size of the formed droplets is affected by the shape of the nozzle tip, and the larger the pressure applied to the coating liquid, the smaller the particle size. Since this method applies pressure to the coating liquid, the discharge amount of the coating liquid increases even when the piping is narrowed, and is not suitable for a small amount of coating.

In the two-fluid atomization method, compressed air is fed into the coating liquid, and the coating liquid is sheared with the compressed air to form a mist. That is, for example, compressed air supply means (not shown) is connected to the spray guns 830 and 940 shown in FIGS. 6 and 7, and compressed air is sent from the compressed air supply means to the coating liquid LQ supplied to the spray guns 830 and 940. Then, the coating liquid LQ is atomized. Further, pattern air supply means (not shown) is connected to the inside of the spray guns 830 and 940, and pattern air is fed from the pattern air supply means, so that the generated mist-like coating liquid LQ is spray gun 830, 940 to discharge.
In such a two-fluid atomization system, the particle size of the formed droplet is affected by the shape of the nozzle tip, and the larger the pressure of the compressed air, the smaller the particle size. In some cases, pressure is applied to the coating liquid to adjust the discharge amount, but the pressure is much lower than that of the one-fluid atomizing system.

In the bell method, the coating liquid is sheared with a cup rotating at high speed to form a mist. That is, for example, a φ20 mm piece (not shown) is used as a cup (not shown), and this piece is rotatably arranged on the flow path inside the spray guns 830 and 940 shown in FIGS. Further, a pattern air supply means (not shown) is connected to the outer peripheral side of the cup inside the spray guns 830 and 940. Then, the coating liquid LQ is supplied from the liquid feed pumps 820 and 920 to the place where the frame is rotated at a high speed (for example, the rotational speed of 72000 rpm) to generate a mist-like coating liquid LQ. At the same time, the generated mist-like coating liquid LQ is discharged from the spray guns 830 and 940 by feeding pattern air from the pattern air supply means.
Usually, such a bell system has a low shear force of the coating liquid because the peripheral speed of the cup is lower than the spray speed of the one-fluid atomization system or the two-fluid atomization system, so that the droplets formed The particle size is larger than that of the fluid atomization type.

(5) Structure of MgO powder As the MgO powder, a vapor phase magnesium oxide single crystal powder having an average particle size measured by the BET method of 500 mm or more (preferably 2000 mm or more) is used.
By forming the crystalline MgO layer 342 using such single crystal MgO powder, the discharge characteristics of the PDP 1 are improved (decrease in discharge delay and increase in discharge probability). That is, in addition to CL emission having a peak at 300 to 400 nm from a single crystal MgO particle having a large particle size contained in the crystalline MgO layer 342 by irradiation with an electron beam generated by discharge, a wavelength region of 200 to 300 nm (particularly, 235 nm). CL emission having a peak in the vicinity (within 230 to 250 nm) is excited. The single crystal MgO grains have an energy level corresponding to the peak wavelength, and can trap electrons for a long time (several milliseconds or more) by the energy level. By taking out these electrons by the electric field, initial electrons necessary for the start of discharge are obtained. As a result, the discharge delay is reduced and the discharge probability is improved.

In the case of single crystal MgO, if the BET equivalent particle diameter of MgO particles is 5000 mm or more, the coating efficiency decreases exponentially, and the amount of coating liquid used increases accordingly. When coating is performed using such MgO particles, a large amount of solvent and MgO are consumed, leading to an increase in production cost and environmental load. Therefore, normally, particles having a particle size of 5000 mm or less are used.
Also, since single crystal MgO usually has a true specific gravity of about 3 and a solvent specific gravity of 1 or less, the sedimentation rate of MgO powder increases. In particular, since the sedimentation speed is proportional to the square of the particle diameter, the larger the particle diameter of the MgO powder, the easier it is to settle. Further, since the MgO powder has high cohesiveness, the MgO powder grows in an aggregated manner when settling occurs in the coating liquid tanks 810 and 910 and in each pipe. Thereby, the aggregate of MgO powder adheres to the flow path of the coating liquid LQ, causing sticking or blockage. For this reason, it is necessary to disperse the MgO powder as much as possible in the coating liquid LQ.

(6) Composition of solvent A solvent having a strong polarity and a low boiling point is used. Examples of such a solvent include substances having a hydroxyl group such as ethanol, glycol, and IPA (2-propanol), and it is particularly preferable to use an alcohol having a monovalent hydroxyl group such as ethanol. In addition, as the solvent, ester compounds such as ethyl acetate and isopropyl acetate, sulfur compounds such as dimethyl sulfoxide, and nitrogen compounds such as dimethylformamide may be used.
According to such a highly polar solvent having a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfone group, or an amine group, hydrogen bonding or electrostatic attraction (polarity) due to Mg or O of the MgO powder and the hydrophilic group in the solvent. Therefore, the solvent molecules surround the outer periphery of the MgO powder, and the MgO powder can be dispersed in the solvent. Further, by using a solvent having a low boiling point, the solvent after coating can be volatilized from the substrate even at room temperature.

(7) Configuration of dispersant A dispersant having a viscosity higher than that of the solvent is used. By using such a dispersant, since the dispersant functions as an adhesive between MgO and the substrate surface, even a MgO powder having a large particle size can be adhered to the substrate surface, and the coating liquid can be applied to the substrate. Can improve the adhesion efficiency. In addition, since the solvent itself has a low viscosity, it is likely to volatilize after coating, and the substrate after coating can be dried at room temperature, preventing aggregation of MgO powder on the substrate. Therefore, it is possible to improve the dispersion state of the MgO powder on the substrate surface.

  In particular, when a substance having a hydroxyl group such as an alcohol is used as the solvent, it is preferable to use a substance having a higher valence of the hydroxyl group than that of the solvent. Thus, the dispersibility of the MgO powder in the coating liquid can be improved by making the valence of the hydroxyl group of the dispersant higher than the valence of the hydroxyl group of the solvent. That is, since the dispersant has more hydroxyl groups than the solvent, the dispersant is more easily adsorbed to the MgO powder than the solvent, and the dispersant more reliably surrounds the outer periphery of the MgO powder in the coating liquid. Enclose. For this reason, it is prevented that MgO powder aggregates in a coating liquid, and the dispersibility of MgO powder improves.

Specific examples of the dispersant as described above include glycerin, ethylene glycol, and 1-octanol. In particular, when glycerin is used, the concentration is 1 to 9 wt%, when ethylene glycol is used, the concentration is 1 to 18 wt%, and when 1-octanol is used, the concentration is 1 to 20 wt%. % Is preferable. Among these dispersants, glycerin having a trivalent hydroxyl group is the most excellent in terms of coating rate, coating surface particle dispersibility and liquid dispersibility, followed by ethylene glycol having a divalent hydroxyl group, water, The order of oxidation groups is monovalent 1-octanol.
When the concentration of glycerin, ethylene glycol and 1-octanol is lower than 1 wt%, when the concentration of glycerin is higher than 9 wt%, when the concentration of ethylene glycol is higher than 9 wt%, the concentration of 1-octanol is 20 wt%. When it is higher than%, the particle dispersibility on the coated surface cannot be improved.

(8) Example An example for confirming the effect of this embodiment will be described below.
(8-1) Dispersibility Evaluation by Using Various Dispersants First, dispersibility evaluation by using various dispersants in the application of MgO powder by a spray method will be described.
The second coating apparatus 900 shown in FIG. 7 was used as the coating apparatus, and the bell system shown in the above (4) was adopted as the atomization system. Specifically, the inside of the coating liquid tank 910 was rotated by rotating a φ40 stirring blade at about 300 rpm so as to prevent sedimentation of MgO particles in the tank. The liquid feed pump 920 was a gear type fixed volume (fixed volume) pump and was driven by an AC motor. The rotation speed of the AC motor was controlled by an inverter. The lengths of the pipe 921 and the pipe 931 were about 10 m, the length of the pipe 932 was about 0.5 m, and PFA tubes each having an inner diameter of 2 mm were used. The spray gun 940 was a bell type. A cup with a diameter of 20 mm was used as the cup, and the cup rotation speed was 72000 rpm. An air supply means (not shown) was connected to the outer peripheral side of the cup inside the spray gun 940, and pattern forming air with an air pressure of 0.5 Mpa was fed into the spray gun 940 from the air supply means. Moreover, the discharge amount of the coating liquid LQ from the spray gun 940 was 10 cc / min.

Soda lime glass was used as the substrate to be coated.
As the MgO powder of the coating liquid, MgO single crystal particles were used, the BET equivalent particle size was 5000 mm, and the powder weight ratio was 5 wt%.
As a solvent for the coating solution, ethanol (monovalent hydroxyl group, viscosity of 0.0012 Pa · S (1.2 cP) at 20 ° C.) was used.
As a dispersant for the coating solution, glycerin (hydroxyl trivalent, viscosity at 20 ° C., 1.412 Pa · S (1412 cP)) having a higher viscosity than the solvent and the valence of the hydroxyl group being equal to or greater than the valence of the solvent, , Ethylene glycol (divalent hydroxyl group, viscosity 0.0232 Pa · S (23.2 cP) at 20 ° C.) and 1-octanol (monovalent hydroxyl group, viscosity 0.00893 Pa · S (8.93 cP) at 20 ° C.) The dispersant concentration was adjusted to 1 to 20 wt% with respect to the total weight of the coating solution.

After spraying the coating liquid LQ onto the substrate under the above conditions, drying was performed at 200 ° C. for 10 minutes in a drying furnace in order to completely dry the solvent and the dispersant.
And the image of the dispersion state of each sample was imaged with a CCD camera, and the surface dispersion state was confirmed visually. During imaging, the substrate was irradiated with 45 ° oblique light in order to clearly raise the state of the grains.

As a result, when glycerin was used as a dispersant, the concentration was 3 wt%, when ethylene glycol was used, the concentration was 5 wt%, and when 1-octanol was used, the concentration was 10 wt%. It was confirmed that the dispersion state of the MgO powder coated on the substrate was the best.
In addition, when the dispersion state in the above-mentioned best state in each dispersant (hereinafter referred to as the best dispersion state) is compared, it can be confirmed that the best dispersion state becomes better in the order of glycerin, ethylene glycol, and 1-octanol. It was. This seems to be an effect of the valence of the hydroxyl group.
Further, in the case of glycerin, the concentration is in the range of 1 to 9 wt%, in the case of ethylene glycol, the concentration is in the range of 1 to 18 wt%, and in the case of 1-octanol, the concentration is in the range of 1 to 20 wt%. Improved. Moreover, in each dispersing agent, the dispersion state of MgO powder deteriorated, so that the addition amount of a dispersing agent became larger than the said upper limit. This is considered to be due to the fact that MgO powder aggregated to form islands as the non-volatile dispersant on the substrate surface aggregated after coating.

Considering the above results, when glycerin was added as a dispersant, the adhesion of MgO powder to the substrate was improved because the viscosity of glycerin was high, and the best dispersion state of MgO powder was the best. Conceivable. However, conversely, since the viscosity of glycerin is high, dry agglomeration is likely to occur, and the upper limit of the concentration at which good results can be obtained is considered to be lower than that of ethylene glycol and 1-octanol.
In addition, when ethylene glycol or 1-octanol was added as a dispersant, the adhesion to the substrate was not as good as when glycerin was added, so it was considered that the best dispersion state was not improved compared to the case of glycerin. It is done. However, with ethylene glycol and 1-octanol, it is difficult for dry aggregation to occur, so it is considered that the dispersion state is improved over a wide concentration range.

(8-2) Observation of dispersion state of MgO powder when glycerin is used Next, in the same manner as in (8-1) above, when 3 wt% of glycerin is added as a dispersant (Example 1), the dispersion The dispersion state of the MgO powder was imaged when no agent was added (Comparative Example 1-1) and when 10 wt% glycerin was added as a dispersant (Comparative Example 1-2). And the influence on the dispersion state of MgO powder by the presence or absence of a dispersant addition and the amount of dispersant added was examined.
FIG. 8 shows an image obtained by binarizing the substrate surface image after coating in Example 1, FIG. 9 in Comparative Example 1-1, and FIG. 10 in Comparative Example 1-2. In these images, a black portion is an aggregate of coated MgO powder, and is an area extracted by binarization.

  Comparing FIG. 8 and FIG. 9, when 3 wt% of glycerin shown in FIG. 8 is added (Example 1), MgO powder is more than when no dispersant is added (Comparative Example 1-1) shown in FIG. It can be seen that the body is finely and uniformly dispersed, and the dispersibility is good. This shows that the dispersibility of the MgO powder can be improved by adding 3 wt% of glycerin as a dispersant.

8 and FIG. 10, when 10 wt% of glycerin shown in FIG. 10 is added (Comparative Example 1-2), there is a portion where the MgO powder is finely dispersed, but the MgO powder aggregates. It can be seen that there are many island-shaped parts. From this, it can be seen that if the amount of glycerin added is excessively increased, island-shaped MgO powder is easily formed, and the dispersibility of the MgO powder decreases.
This result is considered as follows. Since glycerin has a boiling point higher than that of ethanol, ethanol as a solvent is naturally dried after spray coating, but glycerin as a dispersant remains with the MgO powder on the substrate surface without being naturally dried. As the concentration of the dispersant increases, the amount of the dispersant remaining in an undried state on the substrate surface increases, and the dispersant aggregates due to the surface tension of the dispersant when the substrate is dried. And since MgO powder exists in a dispersing agent, it is thought that the dry aggregation of MgO powder became easy to generate | occur | produce. FIG. 10 shows an example in which dry aggregation of the MgO powder occurs, but the dispersibility of the MgO powder further decreases as the amount of dispersant added is further increased.

(8-3) Evaluation of coating efficiency Next, in order to evaluate the coating efficiency for various dispersants, the following experiments were performed for various dispersants, and the MgO powder layers formed on the respective substrates were predetermined. The discharge amount of the coating liquid required to reach a transmittance of 1 was examined for each particle diameter of the MgO powder.
The second coating apparatus 900 shown in FIG. 7 was used as the coating apparatus, and the basic apparatus configuration other than the spray gun 940 was the same as the above (8-1). The spray gun 940 is of a two-fluid air atomization type, the compressed air pressure for atomization supplied to the spray gun 940 is 0.1 MPa, and the pattern air pressure is 0.2 MPa.

Soda lime glass was used as the substrate to be coated.
MgO single crystal particles were used as the MgO powder of the coating solution, the BET equivalent particle diameter was 2200-8300 mm, and the powder weight ratio was 5 wt%.
Ethanol is used as the solvent for the coating solution, and glycerin (Example 2-1), ethylene glycol (Example 2-2) and 1-octanol (Example 2-3) are used as the dispersant for the coating solution. It was. The concentration of each dispersant was set to 3 wt% for glycerin, 5 wt% for ethylene glycol, and 10 wt% for 1-octanol as the concentration when the best dispersion state was obtained in the result of (8-1) above. Further, as Comparative Example 2, a coating solution without adding a dispersant was also prepared.

  After spraying the coating liquid LQ onto the substrate under the above conditions, drying was performed at 200 ° C. for 10 minutes in a drying furnace in order to completely dry the solvent and the dispersant. FIG. 11 shows a coating liquid discharge amount (necessary discharge amount [cc / min]) required for each dispersant to reach a predetermined transmittance of the MgO powder layer formed on the substrate, and MgO. The relationship with the BET conversion particle size [Å] of the powder is shown. The predetermined transmittance here is 80% diffuse transmittance.

  From the results shown in FIG. 11, when forming the MgO powder layer with a desired transmittance, the case where the above-mentioned various dispersants are added (Examples 2-1 to 2-3) is the dispersant. It can be seen that the coating efficiency is higher than that in the case of not adding (Comparative Example 2). It can also be seen that the addition of a high-viscosity dispersant makes it possible to apply a larger particle size MgO powder onto the substrate.

Specifically, in FIG. 11, when the dispersant is not added (Comparative Example 2), the required discharge amount is constant (about 13 [cc / min]) when the BET equivalent particle diameter of the MgO powder is about 5000 mm or less. When the particle size is larger than 5000 mm, the required discharge amount increases exponentially.
On the other hand, when 3 wt% of glycerin is added (Example 2-1), the required discharge rate is constant (about 8 [cc / min]) when the BET equivalent particle size of the MgO powder is about 7000 mm or less, and from 7000 mm The required discharge rate increased for large particle sizes.
Further, when 5 wt% of ethylene glycol is added (Example 2-2), the required discharge amount is constant (about 11 [cc / min]) when the BET equivalent particle diameter of the MgO powder is about 6000 mm or less, and 6000 mm. For larger particle sizes, the required discharge rate increased exponentially.
And when 10 wt% of 1-octanol is added (Example 2-3), the required discharge amount is about the middle between Example 2-2 and Comparative Example 2, and the BET equivalent particle diameter of MgO powder However, the required discharge amount is constant (about 12 [cc / min]) at about 5500 mm or less, and the required discharge amount increases exponentially at a particle size larger than 5500 mm.

  Thus, in the section where the required discharge amount is constant with respect to the BET equivalent particle diameter of the MgO powder, when the various dispersants are added (Examples 2-1 to 2-3), the dispersant is added. It became a small value compared with the case where it does not (Comparative Example 2). Usually, since MgO powder having a particle size of less than 5000 mm is used, the required discharge amount in the certain section is the basic coating efficiency. Therefore, about 30% is applied when glycerin is added (Example 2-1), about 20% when ethylene glycol is added (Example 2-2), and about 10% when 1-octanol is added. It can be said that the wearing efficiency has improved.

  In addition, when various dispersants are added (Examples 2-1 to 2-3), the threshold value of the BET equivalent particle diameter that starts an exponential increase as compared with the case where no dispersant is added (Comparative Example 2). Is high. In particular, when Example 2-1 (glycerin added) and Comparative Example 2 (no dispersant added) were compared, Example 2-1 showed that the threshold value was increased by about 40%. From this, it can be seen that a MgO powder having a larger particle size can be applied onto the substrate by adding a high-viscosity dispersant.

Here, it is considered that the above-described threshold at which the required discharge amount starts increasing with respect to the particle diameter of the MgO powder is due to the following reason.
When the MgO powder is sufficiently small, since the surface energy of the particle surface is high, the adhesion is high and it is easy to adhere to the substrate. And if MgO powder becomes large, it will not have the surface energy which adheres to a board | substrate, and will become difficult to adhere to a board | substrate.
Further, the BET equivalent particle size is usually a value obtained by averaging particle size distributions having a normal distribution. Therefore, even if the MgO powder is larger than the BET particle size that cannot adhere to the substrate, it actually has a distribution and therefore contains a small MgO powder that can adhere to the substrate. Therefore, in FIG. 11, it is considered that the required discharge amount increases exponentially (because the actual particle size distribution is a normal distribution) above a certain particle size.
And when a dispersing agent is added (Example 2-1 to 2-3), since a dispersing agent functions as an adhesive agent of MgO powder and a substrate surface, the same effect as having high surface energy is obtained. Thus, as described above, it is considered that the threshold value of the BET equivalent particle diameter that starts to increase exponentially is increased. In particular, this effect is more pronounced with a dispersant having higher dispersibility of MgO powder and higher viscosity. Therefore, the above threshold is increased in glycerin (Example 2-1) and ethyl glycol (Example 2-2). It is thought that.

(8-4) Verification of discharge delay of PDP 1 when each dispersant is used Next, the following experiment was performed to verify the discharge delay of PDP 1 (see FIG. 1) due to the use of each dispersant.
PDP1 was produced as shown in (2) above. In particular, in the process of forming the crystalline MgO layer 342, the coating apparatus and the coating conditions were the same as in (8-3) above. MgO single crystal particles were used as the MgO powder of the coating solution, the BET equivalent particle size was 5500 mm, and the powder weight ratio was 5 wt%. Ethanol is used as the solvent for the coating solution, and 3 wt% glycerin (Example 3-1), 5 wt% ethylene glycol (Example 3-2), and 10 wt% 1-octanol (implemented) as the dispersant for the coating solution. Example 3-3) The added coating solution was used. Further, as Comparative Example 3, a coating solution without adding a dispersant was also prepared.

  For each PDP 1, the discharge delay was measured at 20 points on the surface of the front substrate 3. FIG. 12 shows the measurement results (range) of the discharge delay at 20 points in the plane. The discharge delay was normalized by the maximum value of the panel not subjected to the single crystal MgO coating. The discharge delay means a time (formation delay + statistical delay) from when a voltage for generating discharge is applied until when discharge actually occurs.

  From the results shown in FIG. 12, it was found that the discharge delay was improved in the case where the dispersant was added (Examples 3-1 to 3-3) compared to the case where the dispersant was not added (Comparative Example 3). In particular, the minimum value of the discharge delay is the smallest when glycerin is added (Example 3-1), followed by ethylene glycol (Example 3-2) and 1-octanol (Example 3-3). I found out that

Thus, the dispersion of the discharge delay was reduced by the addition of various dispersing agents. This is probably because the dispersion of the MgO powder coated on the substrate was improved and the dispersion of MgO contributing to the discharge was reduced. .
Moreover, the minimum value of the discharge delay was decreased by the addition of various dispersants because the adhesion of the large-sized MgO powder was improved by the dispersant. That is, the MgO powder used in this experiment has a BET particle size of 5500 mm. In FIG. 11, when the BET particle size of the MgO powder is 5500 mm, it is included in the region where the required discharge amount increases under the condition that the dispersant is not added (Comparative Example 2), and means that powder having a large particle size does not adhere . Further, ethylene glycol (Example 2-2) and 1-octanol (Comparative Example 2-3) are included in a region where the required discharge amount slightly increases, and glycerin (Example 2-1) changes the required discharge amount. It is included in the area that does not. When the MgO powder particle size is large, it tends to contribute to improvement of the discharge probability (1 / discharge delay). Therefore, the higher the adhesion ratio of the large particle size powder, the better the discharge delay. Therefore, as shown in FIG. 12, by adding various dispersants (Examples 3-1 to 3-3), in particular by adding glycerin (Example 3-1), the minimum discharge delay of PDP1 The value is thought to have decreased.

(9) Effects of PDP 1 Manufacturing Method As described above, according to the PDP 1 manufacturing method of the present embodiment, the following effects can be achieved.

(9-1) In the step of forming the crystalline MgO layer 342, a coating solution in which MgO powder is dispersed in a solvent is applied to the thin film MgO layer 341 by a spray method using the second coating apparatus 900 shown in FIG. Apply on top. A dispersant having a higher viscosity than the solvent is added to the coating liquid.
By using such a dispersant, the dispersant functions as an adhesive between MgO and the substrate surface. For this reason, even MgO powder having a large particle size can be adhered to the substrate surface, and the adhesion efficiency of the coating liquid to the substrate can be improved. Also, in order to uniformly disperse the MgO powder on the substrate, the MgO powder adheres well to the substrate surface even if the air pressure for atomizing the coating liquid or the discharge pressure of the coating liquid is increased. be able to. Thereby, since the usage-amount of a coating liquid and the amount of scattering of a mist-like coating liquid can be reduced, the raise of the manufacturing cost of PDP1 and the cost required for the maintenance of the coating apparatus 900 can be prevented.
In addition, since the solvent itself has a lower viscosity than the dispersant, it is easy to volatilize after coating, and the substrate after coating can be dried at room temperature. If the concentration of the dispersant is set to a predetermined condition, the dispersion of the MgO powder on the substrate surface can be improved without the MgO powder being dried and aggregated by the dispersant remaining on the substrate. it can.
According to the spray method using such a coating liquid, the crystalline MgO layer 342 can be formed uniformly, so that the discharge delay / discharge probability can be made uniform in each discharge cell 231 of the PDP 1. In particular, since MgO powder having a large particle diameter can be used, the discharge delay can be further reduced. Therefore, it is possible to obtain a PDP 1 having uniform brightness and good scanning characteristics.
As described above, according to the method for manufacturing the PDP 1 of the present embodiment, the PDP 1 can be preferably manufactured and the display characteristics of the PDP 1 can be improved.

(9-2) In the coating solution, the solvent and the dispersant are substances having a hydroxyl group, and the valence of the hydroxyl group of the dispersant is preferably not less than the valence of the hydroxyl group of the solvent.
When such a coating solution is used, the dispersant has more hydroxyl groups than the solvent. Therefore, in the coating solution, the dispersant is more easily adsorbed to the MgO powder than the solvent. The outer periphery of the MgO powder can be reliably surrounded. For this reason, since MgO powder does not aggregate in a coating liquid, the dispersibility in the coating liquid of MgO powder can be improved. In addition, by surrounding the outer periphery of the MgO powder with a high-viscosity dispersant, the function of the dispersant as an adhesive between MgO and the substrate surface is further improved, and the efficiency of applying MgO powder to the substrate is further improved. it can.
And since aggregation of MgO powder in each part of a coating apparatus can also be prevented, the blockage | closure of the flow path etc. by adhesion of MgO powder can be prevented, and the stable coating operation | movement of a coating apparatus can be ensured.

(9-3) In the coating solution, the solvent is preferably an alcohol having a monovalent hydroxyl group.
When such a coating solution is used, the polarity of the solvent is strong and its boiling point is low, so that the dispersibility of the MgO powder in the solvent can be improved, and the solvent after coating is volatilized from the substrate even at room temperature. be able to. Thereby, MgO powder can be more uniformly dispersed on the substrate after coating.
Moreover, since aggregation of MgO powder in each part of the coating apparatus can be prevented more reliably, blockage of the flow path due to adhesion of MgO powder can be further prevented, and a more stable coating apparatus coating operation can be obtained. .

(9-4) In the coating liquid, it is preferable to use at least one of glycerin, ethylene glycol, and 1-octanol as a dispersant.
By using such a dispersant, the dispersibility of the MgO powder on the substrate surface after coating, the adhesion efficiency of the MgO powder to the substrate, the adsorptivity of the large-diameter MgO powder to the substrate, and the coating An excellent effect can be obtained in the dispersibility of the MgO powder in the liquid.

(9-5) In the coating solution, when glycerin is used as a dispersant, the concentration is 1 to 9 wt%, and when ethylene glycol is used, the concentration is 1 to 18 wt%, and 1-octanol When is used, the concentration is preferably 1 to 20 wt%.
By using such a dispersant, the dispersion state of the MgO powder on the substrate surface after coating can be reliably improved.

(9-6) In the coating solution, the magnesium oxide powder is preferably a single crystal powder.
When the thin-film MgO layer 341 is formed using such single crystal MgO powder, the display characteristics of the PDP 1 can be improved, such as a reduction in discharge delay and an increase in discharge probability.

(9-7) Ethanol is used as a solvent in the coating solution. And as a dispersing agent, it is preferable to add 3 wt% of glycerol, 5 wt% of ethylene glycol, or 10 wt% of 1-octanol.
In these cases, the best dispersion state of the MgO powder on the substrate surface can be achieved. In particular, when 3 wt% of glycerin is added as a dispersant, the dispersibility of the MgO powder on the substrate surface after coating, the adhesion efficiency of the MgO powder to the substrate, the adsorptivity of the large-diameter MgO powder to the substrate, and the coating The most excellent effect can be obtained in the dispersibility of the MgO powder in the working liquid.

(10) Modification of Embodiments The present invention is not limited to the above-described embodiments, but includes modifications and improvements as long as the object of the present invention can be achieved.

  For example, in the embodiment, the display electrode pair 31 and the dielectric layer 33 are provided on the front substrate 3 side, and the address electrode 21 and the phosphor layers (24R, 24G, 24B) are provided on the back substrate 2 side. Although the reflective AC PDP is illustrated, the present invention is not limited to this. That is, as a PDP to which the present invention can be applied, for example, a reflective AC in which a display electrode pair and an address electrode are formed on the front substrate side, and these are covered with a dielectric layer, and a phosphor layer is formed on the back substrate side. PDP may be used. Further, for example, a transmission AC PDP in which a phosphor layer is formed on the front substrate side, a display electrode pair and an address electrode are formed on the back substrate side, and these are covered with a dielectric layer may be used. That is, the present invention is applicable to any type of PDP as long as the display electrode pair, the dielectric layer, and the protective layer are provided on either the front substrate or the rear substrate. Is also applicable.

  In the above-described embodiment, the protective layer 34 of the front substrate 3 has a two-layer structure including the thin-film MgO layer 341 and the crystalline MgO layer 342. However, the present invention is not limited to this, and the protective layer in the present invention is a crystalline MgO layer. A one-layer structure of 342 may be used. Even in such a case, the crystalline MgO layer 342 can be formed in the same manner as in the above embodiment.

  In the embodiment, the protective layer 34 covers the entire surface of the dielectric layer 33. However, the present invention is not limited to this. For example, the portion of the dielectric layer 33 facing the transparent electrodes 311a and 311b, or conversely, the transparent electrodes 311a and 311a, It may be formed by partially patterning, such as a portion other than the portion facing 311b.

(11) Effects of Embodiment As described above, in the embodiment, in the step of forming the crystalline MgO layer 342, a coating liquid in which MgO powder is dispersed in a solvent is applied to the thin film MgO layer 341 by a spray method. Apply to. A dispersant having a higher viscosity than the solvent is added to the coating liquid.
Thereby, since a dispersing agent functions as an adhesive agent of MgO and a substrate surface, the adhesion efficiency to the board | substrate of MgO powder can be improved. For this reason, while being able to improve the dispersibility of MgO powder on a board | substrate, the quantity of the coating liquid to be used can be reduced. Further, since the solvent itself has a lower viscosity than that of the dispersant, it is easy to volatilize after coating, and the MgO powder can be prevented from drying and agglomerating on the substrate after coating. According to the spray method using such a coating liquid, since the crystalline MgO layer 342 can be formed uniformly, the discharge delay / discharge probability can be made uniform in each discharge cell 231 of the PDP 1. Therefore, it is possible to obtain a PDP 1 having uniform brightness and good scanning characteristics.
Therefore, according to the method for manufacturing the PDP 1 of the present embodiment, the PDP 1 can be preferably manufactured and the display characteristics of the PDP 1 can be improved.

1 is an exploded perspective view showing an internal structure of a plasma display panel according to an embodiment of the present invention. It is the front view which showed typically the plasma display panel in the said embodiment. FIG. 3 is a side sectional view taken along line III-III in FIG. 2. It is a sectional side view along the IV-IV line in FIG. It is the schematic diagram which showed the formation process of the single crystal MgO powder layer in the said embodiment. It is a schematic diagram which shows the 1st coating apparatus in the said embodiment. It is a schematic diagram which shows the 2nd coating apparatus in the said embodiment. It is the image which binarized the board | substrate surface image of Example 1 after coating in the Example which confirms the effect of the said embodiment. It is the image which binarized the board | substrate surface image of the comparative example 1-1 after the coating in the Example which confirms the effect of the said embodiment. It is the image which binarized the board | substrate surface image of the comparative example 1-2 after coating in the Example which confirms the effect of the said embodiment. In the example for confirming the effect of the embodiment, the discharge amount of the coating liquid required until the MgO powder layer formed on the substrate has a predetermined transmittance, the BET equivalent particle diameter of the MgO powder, and It is the graph which showed this relationship for every various dispersing agent. It is a graph which shows the measurement result of the discharge delay of PDP which comprised the crystalline MgO layer formed by the spray method in the Example which confirms the effect of the said embodiment.

Explanation of symbols

1 ... PDP (Plasma Display Panel)
2 ... back substrate 3 ... front substrate 31 ... display electrode pair 33 ... dielectric layer 34 ... protective layer 341 ... thin film MgO layer 342 ... crystalline MgO layer 342A ... single crystal MgO powder 800 ... first coating device 810 ... coating Liquid tank 820 ... Liquid feed pump 830 ... Spray gun 900 ... Second coating device 910 ... Liquid tank 920 ... Liquid feed pump 930 ... Three-way valve 940 ... Spray gun H ... Discharge space LQ ... Coating liquid

Claims (6)

A pair of substrates opposed to each other through the discharge space, a plurality of electrode pairs formed on the inner surface of one of the pair of substrates, a dielectric layer covering the electrode pairs, and the dielectric A method for manufacturing a plasma display panel comprising a protective layer covering a body layer,
The protective layer forming step of forming the protective layer includes a step of applying a coating liquid in which magnesium oxide powder is dispersed in a solvent by a spray method using a spray gun,
A method for producing a plasma display panel, wherein a dispersant having a viscosity higher than that of the solvent is added to the coating liquid. In the manufacturing method of the plasma display panel of Claim 1,
The solvent and the dispersant are substances having a hydroxyl group,
The method for producing a plasma display panel, wherein a valence of a hydroxyl group of the dispersant is not less than a valence of a hydroxyl group of the solvent. In the manufacturing method of the plasma display panel of Claim 1 or Claim 2,
The method for producing a plasma display panel, wherein the solvent is an alcohol having a monovalent hydroxyl group. In the manufacturing method of the plasma display panel in any one of Claims 1 thru | or 3,
As the dispersant, at least one of glycerin, ethylene glycol, and 1-octanol is used. A method for manufacturing a plasma display panel, wherein: In the manufacturing method of the plasma display panel of Claim 4,
As the dispersant,
When glycerin is used, the concentration is 1 to 9 wt%,
When ethylene glycol is used, the concentration is 1 to 18 wt%,
When 1-octanol is used, the concentration is 1 to 20 wt%. A method for manufacturing a plasma display panel, wherein: In the manufacturing method of the plasma display panel in any one of Claims 1 thru | or 5,
The method for manufacturing a plasma display panel, wherein the magnesium oxide powder is a single crystal powder.

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