JP2011258441A - Method of manufacturing plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing PDP for preventing large-small particles of protective layer forming raw materials from mixing at the time of application and drying.SOLUTION: In this method of manufacturing a plasma display panel, a protective layer is formed on a front plate through processes including: (i) a process in which a first protective layer raw material containing first MgO particles and a first solvent and a second protective layer raw material containing second MgO particles and a second solvent are prepared; (ii) a process in which the first protective layer raw material and the second protective layer raw material are simultaneously applied to a dielectric layer formed on a base plate of a front plate and thereby a protective layer raw material layer having a two-layer structure of the first protective layer material layer and the second protective layer material layer is formed; and (iii) the protective layer raw material layer having a two-layer structure is dried; the particle size of the first MgO particles being smaller than that of the second MgO particles in the first and second protective layer raw materials prepared in the process (i), and the surface of the dielectric layer facing downward in the vertical direction when the first and second protective layer raw materials are simultaneously applied to that surface in the process (ii).

Description

  The present invention relates to a method for manufacturing a plasma display panel. More particularly, the present invention relates to the formation of a protective layer, among other methods of manufacturing a plasma display panel.

  A plasma display panel (hereinafter referred to as “PDP”) is a flat display device using radiation from gas discharge. High-speed display and large size are easy, and it is widely put into practical use in fields such as video display devices and public information display devices. There are two types of PDP: DC type (DC type) and AC type (AC type). The surface discharge type AC type PDP has a particularly high technical potential in terms of life characteristics and size, and has been commercialized.

  FIG. 10 is a schematic assembly diagram of a discharge cell structure serving as a discharge unit in a general AC type PDP. As shown in the figure, the PDP (101 ') is formed by bonding a front panel (102') and a back panel (109 '). The front panel (102 ′) has a plurality of display electrode pairs (106 ′) each having a pair of scan electrodes and sustain electrodes on one side of the front panel glass (103 ′). 106 ′) is a panel in which a dielectric layer (107 ′) and a protective layer (108 ′) are sequentially laminated so as to cover. The scan electrode and the sustain electrode are configured by laminating a transparent electrode (120 ') and a bus line (121'), respectively.

  The dielectric layer (107 ') is made of low-melting glass and has a current limiting function unique to the AC type PDP. Then, the surface layer (108 ′) protects the dielectric layer (107 ′) and the display electrode pair (106 ′) from ion collision of plasma discharge, and efficiently emits secondary electrons, thereby reducing the discharge start voltage. Play the role of letting. In general, the surface layer (108 ') is formed by vacuum evaporation or printing using magnesium oxide (MgO) having excellent secondary electron emission characteristics, sputtering resistance, and optical transparency. The same structure as the surface layer (108 ′) is provided as a protective layer for the purpose of securing secondary electron emission characteristics in addition to protecting the dielectric layer (107 ′) and the display electrode pair (106 ′). .

  On the other hand, the back panel (109 ′) has a plurality of data (address) electrodes (111 ′) for writing image data on the back panel glass (110 ′), and the display electrode pair (106) of the front panel (102 ′). It is a panel that is installed side-by-side with '). A dielectric layer (112 ') made of low-melting glass is disposed on the back panel glass (110') so as to cover the data electrode (111 '). On the boundary of the dielectric layer (112 ′) with the adjacent discharge cells (not shown), partition ribs (113 ′) having a predetermined height made of low-melting glass partition (discharge space 115 ′). And a pattern portion (113 ′) such as a cross beam is formed in combination. A phosphor layer (114 ′) (that is, a phosphor layer) formed by applying and firing phosphor inks of R, G, and B colors on the surface of the dielectric layer (112 ′) and the side surfaces of the partition walls (113 ′). R, G, B) are formed.

  The front panel (102 ′) and the back panel (109 ′) are arranged such that the display electrode pair (106 ′) and the data electrode (111 ′) are orthogonal to each other with a discharge space (115 ′). Sealed around each. The discharge space (115 ′) inside the front panel (102 ′) and the back panel (109 ′) is filled with a rare gas such as Xe—Ne or Xe—He as a discharge gas at a pressure of about several tens of kPa. Has been. The PDP (101) is constructed with the above configuration.

  In order to realize the image display by the PDP, a gradation expression method (for example, an intra-field time division display method) that divides an image of one field into a plurality of subfields (SF) is used.

JP 2008-27924 A

  By the way, low-power driving is desired in recent electric appliances, and there is a similar requirement for PDP. In a high-definition PDP, discharge cells are miniaturized and the number of discharge cells is increased, which causes a problem that the operating voltage increases to increase the reliability of the write discharge. As countermeasures against these problems, it is attempted to modify MgO by changing the crystal structure of the MgO protective layer or by adding Fe, Cr and V, Si, and Al as additives to MgO. Yes. Also, a MgO protective layer that can be expected to improve the discharge delay is formed on the dielectric layer or on the MgO film formed by a vacuum deposition method or a sputtering method. A configuration in which MgO powder is applied onto a dielectric layer has also been proposed. In such a conventional technique, a method of applying a powder of MgO by a die coater on an MgO layer formed by a vacuum vapor deposition method has been taken.

  However, considering that the vacuum deposition method called so-called thin film deposition and the die coating method called thick film deposition are performed continuously, the idea that these two layers should be implemented in the same coating process has emerged. Come on. As one of the methods, first, an MgO layer that has been conventionally formed by an evaporation method is formed by using an ink in which fine MgO is dispersed by a die coating method, and after drying, it is slightly larger than the particles of this layer. A method of applying and drying similarly using ink in which MgO is dispersed is conceivable. In particular, the simultaneous application and drying of the two layers is desired in terms of reducing the number of steps, reducing dust generated between the steps, and improving the adhesion between the two layers.

  In order to form a laminated film of MgO particles, it is necessary to provide fine MgO particles in the ink corresponding to the lower layer, while arranging MgO having a particle size several hundred times that of the lower layer particles in the ink corresponding to the upper layer. Here, as a conventional lamination coating, there is a method of manufacturing an optical film (for example, see Patent Document 1). FIG. 11 shows a mode in which ink containing particles is applied by a conventional method described in Patent Document 1. As shown, the inks (40 'and 50') each containing MgO particles are laminated and applied onto the panel (10 ') through the slits (71' and 72 ') of the slit die (70'). After application, the ink is dried by a drying device (not shown). However, in such a conventional method, as shown in FIG. 12, the vertical relationship between the large particles (56 ') and the small particles (46') is switched, and a layered body of mixed particles is generated.

  That is, when two types of inks having different particle sizes are simultaneously applied and dried, the large particles (56 ′) start to settle before the drying of the two layers ends, and the small particles (46 ′) Large particles (56 ') are mixed inside. As a result, there is a concern that the large particles (56 ') that should originally exist on the small particle (46') layer are reduced, and the intended electrical characteristics cannot be obtained as a PDP panel.

  The present invention has been made in view of such circumstances. That is, the subject of this invention is providing the PDP manufacturing method which prevented the large and small particle | grains of a protective layer formation raw material from mixing at the time of application | coating drying.

In order to solve the above problems, the present invention provides a front plate in which an electrode A, a dielectric layer A, and a protective layer are formed on a substrate A, an electrode B, a dielectric layer B, a partition, and a phosphor on a substrate B. A method of manufacturing a plasma display panel, wherein a back plate on which a layer is formed is disposed to face each other,
The formation of the protective layer on the front plate
(I) providing a first protective layer material comprising first MgO particles and a first solvent, and a second protective layer material comprising second MgO particles and a second solvent;
(Ii) By applying the first protective layer raw material and the second protective layer raw material substantially simultaneously to the dielectric layer A formed on the substrate A, the “first protective layer made of the first protective layer raw material” A step of forming a protective layer raw material layer having a two-layer structure of a “raw material layer” and a “second protective layer raw material layer comprising a second protective layer raw material”; and (iii) subjecting the protective layer raw material layer having a two-layer structure to drying Comprising the steps,
For the first protective layer raw material and the second protective layer raw material prepared in step (i), the particle size of the first MgO particles of the first protective layer raw material is smaller than the particle size of the second MgO particles of the second protective layer raw material. And
In the step (ii), the first protective layer raw material and the second protective layer raw material are substantially simultaneously and substantially the same with the “surface of the dielectric layer A to be applied” facing downward in the vertical direction. The first protective layer raw material layer is formed on the dielectric layer A so as to be in contact with the dielectric layer A, and the first protective layer raw material layer is in contact with the first protective layer raw material layer. A method for producing a plasma display panel is provided, wherein a second protective layer raw material layer is formed on the first protective layer raw material layer.

  The production method of the present invention is characterized in that two types of protective layer materials are separately applied simultaneously with the “surface of the dielectric layer A to be applied” facing downward in the vertical direction. That is, as shown in FIG. 1, two types of protective layer raw materials (40, 50) are supplied vertically upward with the coating surface facing the ground side, and two layers are simultaneously coated.

  In the present specification, “the first protective layer raw material and the second protective layer raw material are applied simultaneously” means that the first protective layer raw material is supplied to the surface on which the dielectric layer A is applied, The aspect which supplies 2 protective layer raw materials collectively is substantially meant.

  Further, in this specification, “the state in which the surface of the dielectric layer A to be applied is vertically downward” means that the surface of the dielectric layer provided with the protective layer raw material faces the ground side. Meaning. Therefore, in the present invention, it is sufficient that the surface of the dielectric layer A is large and faces the ground side, and is slightly deviated from the vertical downward direction (for example, the dielectric layer surface is within ± 30 ° from the vertical direction). A side facing side) is also included.

  Further, in the present specification, the “particle size” substantially means the maximum length among the lengths of the particles in all directions. In particular, since the MgO particles used in the present invention can be used in the form of MgO powder, the “MgO particle size” substantially refers to the “average particle size” of the powder particles. Here, the “average particle size” substantially means the particle size calculated as the number average of, for example, the size of 10 particles based on the transmission electron micrograph or optical micrograph of the particles. is doing.

  In a preferred embodiment, for the first protective layer raw material and the second protective layer raw material prepared in step (i), the “sedimentation rate of the second MgO particles in the second protective layer raw material” is “the first MgO in the first protective layer raw material”. It is faster than the “sedimentation rate of the particles”, and “the vapor pressure of the second solvent in the second protective layer material” is lower than “the vapor pressure of the first solvent in the first protective layer material”.

  In another preferred embodiment, the protective layer raw material layer having the two-layer structure formed in the step (ii) is subjected to vacuum drying while maintaining the orientation at the time of formation. That is, in the step (iii), the “two-layer protective layer raw material layer” is vacuum-dried in a state in which the protective layer raw material layer is vertically lower than the dielectric layer A. In such a case, it is preferable to subject the protective layer raw material layer to vacuum drying in two stages. Specifically, it is preferable to carry out two-stage vacuum drying of first vacuum drying and second vacuum drying. In the first vacuum drying, the first protective layer material layer is dried under a first reduced pressure, In the two-vacuum drying, the second protective layer material layer is dried under a second reduced pressure that is further reduced from the first reduced pressure.

  According to the production method of the present invention, it is possible to prevent inconvenience that large and small particles (MgO large particles and MgO small particles) of the protective layer forming raw material are mixed during coating and drying. That is, a small MgO particle layer is formed as the first protective layer on the side close to the coated surface of the panel, and a large MgO particle layer is formed as the second protective layer on the far side. Specifically, as shown in FIG. 2, as the protective layer of the front plate, a “first MgO particle layer (46) obtained by drying the first protective layer raw material layer” is provided on the dielectric layer, and “ A second MgO particle layer (56) obtained by drying the second protective layer raw material layer ”is provided on the first MgO particle layer (46) (first MgO particle size <second MgO particle size).

  In this way, in the present invention, since the MgO small particle layer can be realized as the first protective layer on the side close to the panel substrate and the MgO large particle layer can be realized as the second protective layer on the far side, the obtained PDP has a higher The advantageous effects of low power consumption and high contrast are achieved.

Schematic cross-sectional view showing the aspect of back side lamination coating in the present invention The cross-sectional schematic diagram showing the aspect of the front plate panel (especially protective layer) after the vacuum drying in this invention The figure which showed the structure of PDP typically (FIG. 3 (a): The perspective view which showed the schematic structure of PDP typically, FIG.3 (b): The sectional view which showed the PDP front plate typically) Cross-sectional perspective view schematically showing the steps in the production method of the present invention Graph showing the correlation between particle size and sedimentation velocity in the protective layer material (experimental results) The cross-sectional perspective view which represented typically the aspect of 2 layer simultaneous backside coating in this invention The figure which represented typically the structure of the vacuum exhaust chamber which can be used by this invention Graph showing the degree of vacuum characteristics during vacuum drying in the present invention Electron micrograph when over 80% of the large particles are popping out of the small particle layer Cross-sectional schematic diagram showing the configuration around the protective film of a typical PDP Schematic cross-sectional view showing the state of multilayer coating in the prior art Cross-sectional schematic diagram showing the mode of the front panel (especially protective layer) after vacuum drying in the prior art

  Hereinafter, a method for manufacturing a plasma display panel of the present invention will be described in detail with reference to the drawings. It should be noted that the various elements shown in the drawings are merely schematically shown for understanding of the present invention, and the dimensional ratio, appearance, and the like may differ from the actual ones.

[ Configuration of plasma display panel ]
First, a plasma display panel finally obtained through the manufacturing method of the present invention will be briefly described. FIG. 3A schematically shows the configuration of the PDP in a sectional perspective view, and FIG. 3B schematically shows a sectional view of the front plate of the PDP.

  As shown in FIG. 3 (a), the PDP (100) of the present invention has a structure in which an electrode A (11), a dielectric layer A (15), and a protective layer (16) are provided on a substrate A (10). The front plate (1) ”and the back plate (on which the electrode B (21), the dielectric layer B (22), the partition wall (23), and the phosphor layer (25) are provided on the substrate B (20)). 2) ".

  As shown in the figure, the front plate (1) is provided with the electrode A (11) on the substrate A (10), and the dielectric layer A (15) is disposed on the substrate A (10) so as to cover the electrode A (11). In addition, a protective layer (16) is provided on the dielectric layer A (15). In the back plate (2), an electrode B (21) is provided on the substrate B (20), and a dielectric layer B (22) is provided on the substrate B (20) so as to cover the electrode B (21). A partition wall (23) and a phosphor layer (25) are provided on the body layer B (22). The front plate (1) and the back plate (2) are arranged to face each other so that the protective layer (16) and the phosphor layer (25) face each other. The peripheral portions of the front plate (1) and the back plate (2) are hermetically sealed by a sealing member made of, for example, a low melting point frit glass material (not shown). A discharge space (30) formed between the front plate (1) and the back plate (2) is filled with a discharge gas (such as helium, neon, or xenon) at a pressure of about 20 kPa to 80 kPa, for example.

More specifically, the PDP (100) of the present invention will be described. As described above, the front plate (1) of the PDP (100) of the present invention includes the substrate A (10), the electrode A (11), the dielectric layer A (15) and the protective layer (16). . The substrate A (10) is a transparent and insulating substrate (having a thickness of about 1.0 mm or more and about 3 mm or less). Examples of the substrate A (10) include a float glass substrate manufactured by a float process or the like, and a soda lime glass substrate or a borosilicate glass substrate. A plurality of electrodes A (11) are arranged in parallel in the form of stripes on the substrate A (10), and are, for example, display electrodes including scan electrodes (12) and sustain electrodes (13). In this case, the scanning electrode (12) and the sustaining electrode (13) are respectively “transparent electrodes (12a, 13a) which are transparent conductive films made of indium oxide (ITO) or tin oxide (SnO ₂ )” and the like. It is comprised from "the bus electrode (12b, 13b) which has silver as a main component" formed on the transparent electrode (refer FIG.3 (b)). The transparent electrodes (12a, 13a) mainly function as electrodes that transmit visible light generated in the phosphor layer, while the bus electrodes (12b, 13b) provide conductivity in the longitudinal direction of the transparent electrodes. Mainly functions as an electrode. The thickness of the transparent electrodes (12a, 13a) is preferably about 50 nm or more and about 500 nm or less. The thickness of the bus electrodes (12b, 13b) is preferably about 1 μm or more and about 20 μm or less. As shown in FIG. 3A, a black stripe (14) (light shielding layer) can also be formed on the substrate A (10).

  The dielectric layer A (15) is provided so as to cover the electrode A (11) formed on the surface of the substrate A (10). The dielectric layer A (15) is a film made of a glass composition obtained by applying and heat-treating a dielectric material paste mainly composed of a glass component and a vehicle component (= a component containing a binder resin and an organic solvent). . On the dielectric layer A (15), a protective layer (16) made of, for example, magnesium oxide (MgO) is formed (thickness is about 0.5 μm or more and about 1.5 μm or less).

  On the other hand, as described above, the back plate (2) of the PDP of the present invention includes the substrate B (20), the electrode B (21), the dielectric layer B (22), the partition wall (23), and the phosphor layer (25). It has. The substrate B (20) is preferably a transparent and insulating substrate (thickness is, for example, not less than about 1.0 mm and not more than about 3 mm), for example, a float glass substrate manufactured by a float method or the like. In addition, a soda lime glass substrate, a borosilicate glass substrate, various ceramic substrates, and the like can be given. The electrode B (21) is an electrode (thickness is about 1 μm or more and about 10 μm or less) made mainly of silver and formed in stripes on the substrate B (20). Data electrode). The address electrode mainly has a function of selectively discharging each discharge cell.

  The dielectric layer B (22) is generally called a base dielectric layer, and is provided so as to cover the electrode B (21) formed on the surface of the substrate B (20). The dielectric layer B (22) is a film having a glass composition obtained by applying and heat-treating a dielectric raw material paste mainly composed of a glass component and a vehicle component (= a component including a binder resin and an organic solvent). . The thickness of the dielectric layer B (22) is, for example, not less than about 5 μm and not more than about 50 μm. On the dielectric layer B (22), a phosphor layer (25) mainly composed of a phosphor material is formed (the thickness is, for example, about 5 μm or more and about 20 μm or less). The phosphor layer (25) mainly has a function of converting ultraviolet rays emitted by the discharge into visible light. The phosphor layer (25) has phosphor layers emitting red, green and blue as structural units, and each is separated by a partition wall (23). The barrier ribs (23) are formed on the dielectric layer B (22) in a stripe shape or in a grid pattern for the purpose of partitioning the discharge space for each address electrode (21).

  In the PDP (100) of the present invention, the front plate (1) and the back plate (2) are arranged so that the display electrode (11) of the front plate (1) and the address electrode (21) of the back plate (2) are orthogonal to each other. Are arranged opposite to each other across the discharge space (30). In such a PDP (100), the discharge space (30) partitioned by the partition wall (23) and intersecting the address electrode (21) and the display electrode (11) functions as a discharge cell (32). In other words, the discharge cells arranged in a matrix form an image display area. Accordingly, the discharge gas is discharged by selectively applying the video signal voltage from the external drive circuit to the display electrode (11), and the phosphor layers of the respective colors are excited by the ultraviolet rays generated by the discharge, thereby red, green, and blue. When visible light is generated, color image display is realized.

[ General manufacturing method of PDP ]
Next, a general method for manufacturing a PDP will be briefly described. Unless otherwise stated, the PDP according to the present invention can be obtained based on a general PDP manufacturing method in principle. Unless otherwise specified, raw materials (raw material pastes) / constituent materials of various constituent members may also be those conventionally used in general PDP manufacturing methods.

First, on the substrate A (10) which is a glass substrate, the display electrode (11) composed of the scan electrode (12) and the sustain electrode (13) is formed as the electrode A. The transparent electrodes (12a, 13a) and the bus electrodes (12b, 13b) of the scan electrode (12) and the sustain electrode (13) can be patterned using a photolithography method that exposes and develops. The transparent electrodes (12a, 13a) can be formed by using a thin film process or the like, and the bus electrodes (12b, 13b) are obtained by drying (about 100 to 200 ° C.) and baking (about 400 to 600 ° C.) a paste containing a silver (Ag) material. ). Further, when forming the electrode A, a light shielding layer (14) may also be formed. After the raw material paste containing the black pigment is screen-printed or the raw material containing the black pigment is provided on the entire surface of the glass substrate, exposure / It can be formed by patterning using a photolithography method for development and baking. Next, a glass component (material formed from SiO ₂ , B ₂ O _3, etc.) and a vehicle on the substrate A (10) so as to cover the scan electrode (12), the sustain electrode (13), and the light shielding layer (14). A dielectric material paste mainly composed of components is applied by a die coating method or a printing method to form a dielectric paste layer. After application, if left for a predetermined time, the surface of the applied dielectric paste is leveled to form a flat surface. Thereafter, when the dielectric paste layer is fired, a dielectric layer A (15) is formed. After forming the dielectric layer A (15), a protective film (16) is formed on the dielectric layer A (15). The protective film (16) can be generally formed by using a vacuum deposition method, a CVD method, a sputtering method, or the like.

  Through the above steps, electrodes A (scanning electrode (12) and sustaining electrode (13)), dielectric layer A (15) and protective layer (16), which are predetermined constituent members, are formed on substrate A (10). The front plate (1) is completed.

On the other hand, the back plate (2) is formed as follows. First, the address electrode (21) is formed as the electrode B on the substrate B (20) which is a glass substrate. Specifically, a method of screen printing a paste containing a silver (Ag) material, a method of patterning using a photolithography method in which a metal film mainly composed of silver is formed on the entire surface, and then exposed and developed are used. An address electrode (21) is formed by forming a precursor layer and firing it at a desired temperature (eg, about 400 to about 600 ° C.). This “address electrode” may be formed by patterning a chrome / copper / chromium three-layer thin film coated with a photoresist by photolithography and wet etching. Next, a dielectric layer B (22) serving as a base dielectric layer is formed on the substrate B (20) on which the address electrodes (21) are formed. First, a “dielectric material paste mainly composed of a glass component (a material formed from SiO ₂ , B ₂ O ₃ or the like) and a vehicle component” is applied by a die coating method or the like to form a dielectric paste layer. And dielectric layer B (22) can be formed by baking this dielectric paste layer. Next, a partition wall (23) is formed. First, a dielectric material paste is applied onto the dielectric layer B (22) and patterned into a predetermined shape to form a partition wall material layer, which is then baked to form the partition wall (23). To do. For example, by a photolithography method in which a raw material paste mainly composed of a low-melting glass material, a vehicle component and a filler is applied by a die coating method or a printing method, dried at about 100 ° C. to 200 ° C., and then exposed and developed. The partition wall (23) is formed by patterning and then baking at about 400 ° C. to about 600 ° C. Subsequent to the formation of the partition wall (23), the phosphor layer (25) is formed. A phosphor raw material paste containing a phosphor material is applied on the dielectric layer B (22) between the adjacent barrier ribs (23) and on the side surfaces of the barrier ribs (23), and baked to form the phosphor layer (25). . More specifically, the phosphor paste is prepared by applying a raw material paste mainly composed of phosphor powder and a vehicle component by a die coating method, a printing method, a dispensing method, an ink jet method or the like, and then drying at about 100 ° C. A layer (25) is formed.

  Through the above steps, the electrode B (address electrode (21)), the dielectric layer B (22), the partition wall (23), and the phosphor layer (25), which are predetermined constituent members, are formed on the substrate B (20). The back plate (2) is completed.

  In this way, the front plate (1) and the back plate (2) provided with predetermined constituent members are arranged to face each other so that the display electrodes (11) and the address electrodes (21) are orthogonal to each other. Next, the periphery of the front plate (1) and the back plate (2) is sealed with a glass frit, and a discharge gas (helium, neon, xenon, etc.) is sealed in the discharge space (30) to be formed. 100) is completed.

[ Production method of the present invention]
The method of the present invention is particularly characterized in the formation of a protective layer on the front plate side in PDP production. Such protective layer formation is characterized in that two types of protective layer raw materials are simultaneously applied with the dielectric layer surface to which the raw material is applied facing downward in the vertical direction (see FIG. 1). That is, two types of protective layer raw materials are “back-layer coating” or “back-layer coating”.

  The production of the front plate will be described with reference to FIGS. When manufacturing the front plate, first, a “substrate on which electrodes are formed” is prepared. The “substrate on which the electrode is formed” means “the substrate A on which the electrode A on the front plate side is formed”, and more specifically, as shown in FIG. (11) means a glass substrate (10) ". That is, a glass substrate (10) having a display electrode (11) composed of a scan electrode (12) and a sustain electrode (13) is prepared. The substrate (10) is preferably an insulating substrate made of soda lime glass, high strain point glass, or various ceramics, and the thickness is preferably about 1.0 mm to 3 mm. The scan electrode (12) and the sustain electrode (13) are formed with transparent electrodes (12a, 13a) made of ITO or the like having a thickness of about 50 to 500 nm, respectively, and transparent to lower the resistance value of the display electrode. On the electrodes, bus electrodes (12b, 13b) having a thickness of about 1 to 20 μm containing silver are formed. Specifically, after forming the transparent electrode by a thin film process or the like, the bus electrode is formed through a firing process or the like. In particular, when forming the bus electrode, first, a conductive paste mainly composed of silver is formed in a stripe shape by a screen printing method. In addition, the bus electrode is formed in a stripe shape by applying a photosensitive paste mainly composed of silver by a die coating method or a printing method, drying at 100 ° C. to 200 ° C., and then patterning by a photolithography method that exposes and develops. You may form in. Alternatively, a dispensing method or an ink jet method may be used. Finally, after subjecting to drying, a bus electrode can be obtained by subjecting to baking at 400 ° C. to 600 ° C. On the transparent electrode, a metal electrode made of a metal such as Al, Cu or Cr or a laminate such as Cr / Cu / Cr may be formed.

Subsequent to the formation of the display electrode (11), a dielectric layer (15) is formed as shown in FIG. The dielectric layer (15) can be obtained by a firing method or a sol-gel method used in general production of a PDP front plate. For example, a dielectric material paste formed by mixing glass powder containing SiO ₂ , B ₂ O ₃ , ZnO, Bi ₂ O ₃ , an organic solvent, and a binder resin is applied by screen printing, and then subjected to heat treatment. Thus, a dielectric layer can be formed. The thickness of the dielectric layer (15) is preferably about 5 μm to 30 μm, more preferably about 10 μm to 20 μm. Examples of the organic solvent include alcohols (for example, isopropyl alcohol) and ketones (for example, methyl isobutyl ketone), and examples of the binder resin include cellulose resins and acrylic resins.

  Subsequent to the formation of the dielectric layer (15), the protective layer (16) is formed. Therefore, first, step (i) of the manufacturing method of the present invention is performed. Specifically, “a first protective layer material comprising first MgO particles and a first solvent” and “a second protective layer material comprising second MgO particles and a second solvent” are prepared.

  The first protective layer material can be prepared by mutually mixing “MgO particle powder as first MgO particles” and “organic solvent as first solvent”. The first MgO particles are preferably MgO crystal powder (MgO microcrystal powder), more preferably MgO single crystal powder. The particle diameter of the first MgO particles is smaller than the size of the second MgO particles of the second protective layer material, preferably 50 nm or less, more preferably about 5 nm to 50 nm, and still more preferably about 15 nm to 50 nm. is there. And it is preferable that content of the 1st MgO particle | grains of a 1st protective layer raw material is larger than content of the 2nd MgO particle | grains of a 2nd protective layer raw material, For example, Preferably it is about 6 to 20 weight% (1st protective layer raw material) And more preferably about 8 to 15% by weight (based on the total weight of the first protective layer raw material). Examples of the organic solvent used as the first solvent include 3-methoxy-3-methyl-1-butanol, n-heptyl alcohol, 2-ethoxyethanol, 2-methoxyethanol, n-hexyl alcohol, and 2-methyl-1-propanol. And organic solvents such as α-terpineol, propylene glycol, 2-octanol, dipropylene glycol, diethylene glycol monobutyl ether, tripropylene glycol methyl ether, or glycerin. Here, the organic solvent used as the first solvent preferably has a vapor pressure higher than the vapor pressure of the second solvent of the second protective layer raw material (for example, 3-methoxy-3-methyl-1-butanol is used. Can be used as the first solvent). The content of the first solvent in the first protective layer raw material is preferably about 80 to 95% by weight (based on the total weight of the first protective layer raw material), more preferably about 85 to 95% by weight (first protective layer raw material). Based on the total weight). In addition, as the organic solvent of the first solvent, a mixture obtained by combining at least two kinds of solvents selected from the organic solvents exemplified above may be used.

  The second protective layer material can be prepared by mutually mixing “MgO particle powder as second MgO particles” and “organic solvent as second solvent”. The second MgO particles are preferably MgO crystal powder (MgO microcrystal powder), more preferably MgO single crystal powder. The particle diameter of the second MgO particles is larger than the first MgO particles of the first protective layer material, and is preferably 1 μm or more, more preferably about 1 μm to 20 μm, and still more preferably about 1 μm to 5 μm. The content of the second MgO particles in the second protective layer raw material is preferably smaller than the content of the first MgO particles in the first protective layer raw material, for example, preferably about 0.3 to 8% by weight (second protection) Based on the total weight of the layer raw material), more preferably about 0.3 to 2% by weight (based on the total weight of the second protective layer raw material). Examples of the organic solvent used as the second solvent include P-ment-1-en-8-ol, 3-methoxy-3-methyl-1-butanol, n-heptyl alcohol, 2-ethoxyethanol, 2-methoxyethanol, n In addition to organic solvents such as hexyl alcohol or 2-methyl-1-propanol, α-terpineol, propylene glycol, 2-octanol, dipropylene glycol, diethylene glycol monobutyl ether, tripropylene glycol methyl ether, glycerin, etc. Organic solvents can also be mentioned. Here, the organic solvent used as the second solvent preferably has a vapor pressure lower than the vapor pressure of the first solvent of the first protective layer raw material (for example, P-menta-1-ene-8- All can be used as the second solvent). The content of the second solvent in the second protective layer material is preferably 92 to 99.7% by weight (based on the total weight of the second protective layer material), more preferably 98 to 99.7% by weight (second protection). Based on the total weight of the layer raw material). In addition, as an organic solvent of a 2nd solvent, you may use the mixture which combined the at least 2 or more types of solvent chosen from the organic solvent which was illustrated above.

  In particular, in the present invention, as the solvent for the first protective layer raw material and the second protective layer raw material, those having different components may be selected, and those having different vapor pressures and viscosities may be selected. That is, as the organic solvent for the first protective layer raw material and the second protective layer raw material, those which are mutually soluble but have different viscosities and saturated vapor pressures (boiling points) may be used.

  For example, as to the vapor pressure of the protective layer material, as described above, the vapor pressure of the second solvent of the second protective layer material is lower than the vapor pressure of the first solvent of the first protective layer material. preferable. In other words, the vapor pressure of the first solvent in the first protective layer material is preferably higher than the vapor pressure of the second solvent in the second protective layer material. Thus, “two-stage vacuum drying” described later can be suitably performed. For example, the vapor pressure value is preferably different by about two orders of magnitude between the first protective layer raw material and the second protective layer raw material. More specifically, the vapor pressure of the first solvent of the first protective layer raw material is different. The vapor pressure of the second solvent of the second protective layer material is preferably higher by about 10 to 100 times.

Here, in the present invention, “the size of the first MgO particles contained in the first protective layer material” is smaller than “the size of the second MgO particles contained in the second protective layer material”. In general, particles are affected by gravity in a liquid, and when gravity exceeds buoyancy, a sedimentation phenomenon occurs in the liquid. Regarding the sedimentation velocity, the generally known Stokes equation is as follows.
(Formula 1)
As can be seen from Equation 1, the sedimentation rate of the particles in the liquid is generally proportional to the square of the particle radius. That is, the larger the particle size, the greater the settling speed in the liquid. In this regard, in the present invention, since the second MgO particles are larger in size (particle diameter) than the first MgO particles, the sedimentation rate of the second MgO particles in the second protective layer raw material is determined by the first protective layer raw material. It becomes faster than the sedimentation rate of the first MgO particles therein. In fact, when the experimental results for the protective layer material used in the present invention are plotted, it is on a quadratic curve, and it is understood that the general relationship between the sedimentation velocity and the particle size represented by Equation 1 is established (see FIG. 5). Specifically, when the diameter of the first MgO particles (small particles) is 50 nm or less and the diameter of the second MgO particles (large particles) is about 1 μm or more, the settling speed is 400 times as long as the solvent is the same from Equation 1 Different results are expected. In particular, in the case of a small particle level, almost no sinking occurs due to the influence of van der Waals force between particles, so that it is expected that the difference in sedimentation speed will be further widened. As a result of actually measuring the sedimentation rate in the low-viscosity raw material, it was impossible to measure about 1 μ / s for large MgO particles of 1 μm or more and small MgO particles of 50 nm or less. Therefore, assuming that each thickness of the protective layer raw material layer is 10 μm in the prior art, in such a coated thin film, the large MgO particles present in the upper layer reach the boundary between the upper layer and the lower layer in about 10 seconds. It is considered that the liquid may settle down and then dissolve into the lower layer as it is, or may enter the lower layer when it is dried.

  In this regard, in the present invention, although the upper layer (= second protective layer) finally contains large second MgO particles, as described later, the first protective layer raw material layer and the first layer Since the two protective layer raw material layers are laminated on the back surface (see FIG. 1), the second MgO particles (large particles) of the second protective layer raw material layer are prevented from entering the first protective layer raw material layer. . Rather, in the back lamination state, the force that the second MgO particles of the second protective layer raw material layer try to settle down in the vertical direction works and can move away from the first protective layer raw material layer. The small first MgO particles are suitably segregated.

  By the way, a specific example is given for the “precipitation speed V2 of the second MgO particles in the second protective layer raw material is faster than the precipitation speed V1 of the first MgO particles in the first protective layer raw material” in the present invention. For example, V2 is about 2 to 450 times (for example, about 400 times) larger than V1.

  Subsequent to step (i) of the production method of the present invention, step (ii) is performed. That is, the first protective layer raw material and the second protective layer raw material are simultaneously applied onto the dielectric layer A formed on the substrate A. In the present invention, a protective layer material layer having a two-layer structure of “a first protective layer material layer made of a first protective layer material” and “a second protective layer material layer made of a second protective layer material” is formed by such simultaneous application. Form.

  In particular, in the present invention, the first protective layer raw material and the second protective layer raw material are simultaneously applied in a backside laminated state. More specifically, as shown in FIG. 4C and FIG. 6, the first protective layer material (40) with the surface of the dielectric layer A (15) to be applied faced downward in the vertical direction. ) And the second protective layer raw material (50) are simultaneously applied. Thus, the first protective layer raw material layer (40A) is formed in contact with the dielectric layer A (15), and the second protective layer raw material layer (50A) is formed on the first protective layer raw material layer (40A). (See FIG. 4D).

  A slit die is preferably used for coating the protective layer material. In particular, in the present invention, it is preferable to use a slit die (70) provided with two slit portions so that “lamination coating” can be performed (see FIGS. 1 and 6). In particular, as shown in FIG. 1, the slit die (70) to be used is divided into three parts and includes two slit parts (71 and 72) serving as a raw material discharge part. Thereby, simultaneous application | coating of a 1st protective layer raw material and a 2nd protective layer raw material is attained. Preferably, the slit thickness (t1, t2) is about several tens to several hundreds μm. The shape of the slit die (70) and the shape and number of the divided portions are not limited to those described, but various shapes such as a type in which the tip of the central portion of the three divided portions has an acute angle, Number is conceivable. Further, the position between the lips may be changed as appropriate by changing the mounting height of these divided portions. In any type of slit die, in the present invention, the coating surface is directed downward (that is, “downward in the vertical direction”), so that the slit portions (71, 72) are on the upper side (that is, as shown in FIG. 6). The slit die will be installed so that it faces the “vertical upper side”).

  The raw material supply to the slit die (70) may be performed using a pump such as a tube pump or a syringe pump. Further, since the first protective layer raw material and the second protective layer raw material contain particles, a circulation mechanism including a pump or the like may be provided as a peripheral circuit of the slit die (70) in order to suppress particle sedimentation.

In order to suitably perform the lamination coating using the slit die as described above, it is preferable that the first protective layer raw material and the second protective layer raw material have a viscosity of about 15 mPa · s or less. More specifically, the viscosity of the first protective layer raw material and the second protective layer raw material is preferably 3 mPa · s or more and 15 mPa · s or less so that the back surface lamination coating using a slit die is suitably performed. Yes, more preferably 4 mPa · s or more and 10 mPa · s or less. Since the first protective layer raw material and the second protective layer raw material can generally be a non-Newtonian fluid, the viscosity used in this specification substantially means “viscosity at a shear rate of 100 s ⁻¹ and a temperature of 25 ° C.”. Yes.

  In the simultaneous application of the first protective layer raw material and the second protective layer raw material, as shown in FIG. 6, the “substrate (10) on which the electrode (11) and the dielectric layer (15) are formed” is placed below the coated surface. It will be installed toward the side (ground side). In the illustrated embodiment, the substrate (10) to be applied is represented by a single-wafer specification such as a glass panel, but if the application surface can always face the ground side, a roll-to-roll method, etc. May be adopted. Even when the roll-to-roll method is adopted, in the present invention, the coating surface is directed downward (that is, “vertically downward”), so that the slit die has an upper slit portion (that is, “vertically upward”). ).

  The thickness (Wet film thickness) of the first protective layer raw material layer (40A) formed by back surface lamination coating is preferably about 3 μm to 15 μm. On the other hand, the thickness (Wet film thickness) of the second protective layer raw material layer (50A) formed by back layer coating is preferably about 3 μm to 20 μm (see FIG. 4D).

  Once the first and second protective layer raw material layers are formed, next, step (iii) of the production method of the present invention is performed. Specifically, the protective layer raw material layer (60) having a two-layer structure shown in FIG. 4 (d) is subjected to drying. That is, the first protective layer raw material layer is subjected to drying to obtain a first protective layer (ie, the first MgO particle layer), and the second protective layer raw material layer is subjected to drying to obtain the second protective layer (ie, the first protective layer raw material layer). A second MgO particle layer) is obtained. Here, “drying” substantially means that the solvent contained in the raw material layer (more specifically, the first solvent and the second solvent) is vaporized and removed from the raw material layer. . For example, the protective layer raw material layer may be placed under reduced pressure or vacuum of 7 to 1 Pa, preferably 7 to 0.1 Pa, or may be subjected to heat treatment at about 100 to 400 ° C. under atmospheric pressure. If necessary, “under reduced pressure or under vacuum” and “heat treatment” may be combined. The total thickness of the protective layer obtained after drying is reduced from the thickness of the raw material layer due to the removal of the solvent, and can be about 0.2 to 5 μm as a whole.

  In particular, in the present invention, it is preferable to perform vacuum drying while maintaining the orientation of the protective layer raw material layer having the two-layer structure formed in step (ii). That is, in the step (iii), it is preferable that the protective layer raw material layer having a two-layer structure is subjected to vacuum drying in a state where the protective layer raw material layer is positioned below the dielectric layer A in the vertical direction. As a result, “the large second MgO particles contained in the second protective layer raw material layer (50A)” and “the small first MgO particles contained in the first protective layer raw material layer (40A)” are suitable during the drying process. The state of being segregated is maintained.

  When performing vacuum drying, an apparatus (80) as shown in FIG. 7 can be used. The vacuum drying apparatus (80) includes a vacuum chamber (81), a conductance valve (82) having a pressure adjusting function, a pump (83), and a vacuum gauge (84). The substrate to be applied can be installed with the application surface facing the ground side by a suspension mechanism (not shown). Although not shown in FIG. 7, a transfer robot (not shown) may be installed for substrate replacement.

  In the vacuum drying apparatus (80), a “substrate (10) including an electrode, a dielectric layer and a protective layer raw material layer (60)” is installed in a vacuum chamber (81). For example, the substrate (10) is transported to the vacuum chamber (80) with the application surface being on the ground side using a robot or the like. When the substrate (10) to be coated is placed in the vacuum chamber (80), evacuation is started using the pump (83). In evacuation, the conductance valve (82) is used to control the change in the evacuation speed at the initial stage of evacuation while checking the value of the vacuum gauge (84) so that bumping does not occur from within the protective layer material layer (60) due to sudden pressure reduction. It is preferable to do. For example, although it may depend on the chamber size and the exhaust capacity, bumping can be more suitably suppressed by controlling so that it takes about 30 seconds to reach a vacuum degree of 1000 Pa or less. Incidentally, when the ultimate pressure of 1 Pa or less and the exhaust capability required for complete drying of the protective layer raw material layer are insufficient, an ultra-high vacuum compatible pump such as a turbo pump may be added before the pump (83). In that case, similarly, it is preferable to control the conductance valve (82) and adjust the exhaust start timing of the turbo pump so as not to reach a high vacuum at a time.

  In the present invention, it is preferable to subject the protective layer raw material layer to vacuum drying in two stages in order to more suitably prevent bumping. Specifically, it is preferable to carry out two-stage vacuum drying including first vacuum drying and second vacuum drying. For example, in the first vacuum drying, the first protective layer raw material layer is dried under a first reduced pressure, and in the second vacuum drying, the second protective layer raw material layer is dried under a second reduced pressure further reduced from the first reduced pressure. Let Thereby, the first protective layer raw material layer (40A) and the second protective layer raw material layer (50A) are individually dried at different times, and are contained in the "second protective layer raw material layer (50A)". The “second MgO large particles” and the “first MgO small particles contained in the first protective layer raw material layer (40A)” are more appropriately separated.

  FIG. 8 is a drying curve when vacuum evacuation is performed, and is a drying curve in which the degree of vacuum in the vacuum chamber (81) is graphed on the time axis from the start of evacuation. The protective layer material layer is vaporized from a liquid state by evacuating the vacuum chamber, and starts to evaporate, that is, dry. Generally, when the vapor pressures of the low-viscosity raw material layer (low-viscosity raw material) and the high-viscosity raw material layer (high-viscosity raw material) are compared, the vapor pressure of the low-viscosity raw material layer> the vapor pressure of the high-viscosity raw material layer. The raw material layer is harder to dry. When evacuating a closed space in which a laminate of a low-viscosity raw material layer and a high-viscosity raw material layer is provided, it should be carried out so as to obtain a two-part vacuum degree curve as shown in FIG. Is preferred. That is, when evacuation is started, the pressure first rises around the vapor pressure of the low-viscosity raw material, and the degree of evacuation is reduced at that point to promote drying of the low-viscosity raw material layer. When the drying of the low-viscosity raw material layer is completed, the vacuuming is further advanced to the degree of vacuum at which the high-viscosity raw material layer is vaporized to start the drying of the high-viscosity raw material layer. When drying of the high-viscosity raw material layer is started (an increase in the degree of vacuum is observed near the vapor pressure of the high-viscosity raw material), similarly, the degree of vacuuming is reduced to promote drying of the high-viscosity raw material layer. If it does in this way, the laminated body of a low-viscosity raw material and a high-viscosity raw material layer can be vacuum-dried in two steps.

  In the present invention, the first protective layer raw material layer is preferably formed as a low viscosity layer, and the second protective layer raw material layer is preferably formed as a high viscosity layer. For this purpose, it is preferable that the viscosity of the first protective layer material is, for example, about 30 mPa · s to 100 mPa · s, while the viscosity of the second protective layer material is, for example, about 3 mPa · s to 10 mPa · s. A mode in which the first protective layer raw material layer and the second protective layer raw material layer are vacuum-dried in two stages using a vacuum drying apparatus (80) shown in FIG. 7 will be described. First, evacuation of the vacuum chamber (81) is started by the pump (83) in a state where the opening of the conductance valve (82) is small, and the first protective layer material layer having a high vapor pressure in a vacuum region of about several hundred Pa is used. Start drying. Then, the opening degree of the conductance valve (82) is increased, the vacuum is exhausted to a high vacuum region of about several Pa, and the second protective layer material layer having a low vapor pressure is dried. If the evacuation is performed to the high vacuum region at once without adjusting the conductance valve (82), the two types of protective layer raw material layers may be dried at the same time. Therefore, it is preferable to adjust the exhaust speed carefully. In order to appropriately perform this pressure control within an effective range, it is desirable that there is a vapor pressure difference of about two digits between the first protective layer raw material and the second protective layer raw material as described above. Thus, when vacuum drying is performed in two stages, a small MgO particle layer is suitably formed as the first protective layer on the side close to the substrate, and a large MgO particle layer is formed as the second protective layer on the far side.

  By going through the above steps (i) to (iii), from the “first MgO particle layer formed from the first protective layer raw material layer” and the “second MgO particle layer formed from the second protective layer raw material layer” A protective layer having a two-layer structure is obtained, and the front plate is finally completed. In particular, in the present invention, a protective layer in which a film of small first MgO particles is formed in the first layer close to the substrate, and the second layer of large particles is interspersed as the second layer on the surface. Is obtained.

Below, the content of the experiment conducted in connection with this invention and implementation operation are demonstrated. In the following description, the protective layer material is referred to as “ink” for convenience.
(Table 1)

  Four experiments (Experiments 1-1, 2-1, 3-1, and 4-1) described in the upper part of Table 1 were performed using the method of the prior art shown in FIG. The ink 50 'was changed. On the other hand, the four experiments (Experiments 1-2, 2-2, 3-2 and 4-2) described in the lower part are the results of experiments using the coating and drying method of the present invention shown in FIG. Similarly, the ink 40 and ink 50 components are changed.

The following solvents were used as ink solvents.
High viscosity ink solvent: P-Ment-1-en-8-ol Vapor pressure 5 Pa (at room temperature)
Low viscosity ink solvent: 3-methoxy-3-methyl-1-butanol Vapor pressure 200Pa (at room temperature)

  As the particles contained in the ink, MgO particles were used for both the small particles and the large particles so that the particle diameters were different between the inks.

  In Table 1 above, the condition of Experiment 1-2 was judged to be the best performance. Such performance evaluation was performed by observing by SEM how much the large particles protrude from the small particle layer after drying (see FIG. 9). In the evaluation criteria, “○” indicates that 80% or more of the large particles are protruding from the small particle layer (the “jumping degree” shown in FIG. 9), and “◎” indicates the large particles. This is a case where 90% or more of the above has protruded from the small particle layer. On the contrary, “Δ” indicates that less than half of the large particles protrude from the small particle layer, and “X” indicates that no large particles protrude from the small particle layer.

  The content of the experiment conducted in this example will be described over time. First, two types of ink were pushed into the slit die by the respective extrusion pumps. Thus, the ink that was pushed into the slit die from the two slits was ejected to move the slit die (or panel 10) to form two ink layers. In the experiment of the present invention, since the coating film thickness of each layer was set to several tens to several hundreds of μm, the amount of ink supplied to each layer at the time of coating was several mL to several tens mL when the 42-inch panel size was applied with the above thickness. Become. In the applied panel, two types of ink are laminated, and the ink layer closer to the substrate contains small particles, and the far ink layer contains large particles. The laminated and coated panel substrate was conveyed to the vacuum chamber with the coated surface on the ground side. And after moving to a vacuum chamber, the pump was driven and evacuation was implemented. At this time, the change in the exhaust speed at the initial stage of exhaust was controlled by using a conductance valve so as not to cause bumping from the inside of the coating film due to sudden pressure reduction. Although it depends on the chamber size and exhaust capacity, it was found from this experiment that it takes more than 30 seconds to reach a vacuum level of 1000 Pa or less, which is more effective for suppressing bumping.

(Consideration of results)
Considering the experimental conditions and results of performance evaluation, the following can be considered as phenomena occurring in each Run.
● First, in the case of Experiments 2-1 and 4-1, where the same solvent is used for the ink 40 ′ and the ink 50 ′, which are conventional examples, the small particles in the lower layer ink have a small particle size, and thus hardly settle in the ink. On the other hand, the large particles in the upper layer ink settle down at a high speed due to the large particle size, and the large particles in the lower layer ink where small particles exist after coating until drying. It is thought that it was mixed. As a result, it is considered that a portion in which the vertical relationship between the large particles and the small particles is reversed occurs and a desired characteristic cannot be obtained.
In addition, when the inks 40 ′ and 50 ′ are different from each other in the conventional example, after application, the large particles start to settle in the ink and move to the boundary surface between the ink 40 ′ and the ink 50 ′. When vacuum drying is performed in this state, the large particles are found in the small particle layer as seen from the observation result, which is also a problem.
In the case of Experiment 2-2 or 4-2, the drying starts from the layer of the ink 50 at the time of drying after application as in the case of the above Experiment 2-1 or 4-1; Since the large particles are mixed in the same solvent, there is a part where small particles exist on the surface of the large particle layer at the time of final drying. . The reason why the result of 2-2 using the low-viscosity ink is better than that of 4-2 is thought to be that the drying time is longer and the mixing phenomenon occurs more.
● Experiment 1-2 was the best result. First, when drying, the low-viscosity ink 40 started to dry, and after forming a small particle layer on the panel surface, the high-viscosity ink 50 containing large particles 50 This is probably because the dispersion state of the large particles was suitably formed on the surface of the small particle layer.

  Since the PDP obtained by the production method of the present invention has a front-surface dielectric layer suitably covered with a modified protective layer, it can be used as a general-use television set and a commercial display. It can also be suitably used for other display devices.

  Further, the production method of the present invention can form particle laminates of different sizes by “simultaneous coating and drying”, so that not only PDP production but also control of particle layer formation, LCD, organic EL, etc. The present invention can also be applied to applications such as display panels, optical films, and painting processes such as steel sheets and cloth.

(Codes related to the present invention)
DESCRIPTION OF SYMBOLS 1 Front plate 2 Back plate 10 Front board side board 11 Front board side electrode (display electrode)
12 Scan electrode 12a Transparent electrode 12b Bus electrode 13 Sustain electrode 13a Transparent electrode 13b Bus electrode 14 Black stripe (light shielding layer)
DESCRIPTION OF SYMBOLS 15 Dielectric layer by the side of a front board 16 Protection layer 20 Board | substrate by the side of a back board 21 Electrode (address electrode) by the side of a back board
22 dielectric layer on the back plate side 23 partition wall 24 groove portion 25 phosphor layer 26 partition wall upper layer 30 discharge space 32 discharge cell 40 first protective layer raw material 40A first protective layer raw material layer 46 first MgO particles (small particles)
48 1st solvent 50 2nd protective layer raw material 50A 2nd protective layer raw material layer 56 2nd MgO particle (large particle)
58 Second solvent 60 Two-layer protective layer raw material layer 70 Slit die 71 First slit portion 72 Second slit portion 80 Vacuum dryer 81 Vacuum chamber 82 Conductance valve 83 Pump 84 Vacuum gauge 100 PDP
(Codes related to conventional and background technologies)
10 'panel 16' protective layer 40 'ink 46' MgO small particles 48 'ink solvent 50' ink 56 'MgO large particles 58' ink solvent 70 'slit die 71' first slit portion 72 'second slit portion 101' PDP
102 'front panel 103' front panel glass 104 'sustain electrode 106' display electrode pair 107 'dielectric layer 108' protective layer 109 'back panel 110' back panel glass 111 'data electrode 112' dielectric layer 113 'barrier rib (rib )
114 'phosphor layer 115' discharge space 120 'transparent electrode 121' bus line

Claims (5)

The front plate in which the electrode A, the dielectric layer A, and the protective layer are formed on the substrate A is opposed to the back plate in which the electrode B, the dielectric layer B, the partition wall, and the phosphor layer are formed on the substrate B. A plasma display panel manufacturing method comprising:
The formation of a protective layer on the front plate
(I) providing a first protective layer material comprising first MgO particles and a first solvent, and a second protective layer material comprising second MgO particles and a second solvent;
(Ii) By simultaneously applying the first protective layer raw material and the second protective layer raw material to the dielectric layer A formed on the substrate A, the first protective layer raw material layer and the second protective layer raw material layer; Forming a protective layer raw material layer having a two-layer structure, and (iii) subjecting the protective layer raw material layer to drying,
In the first protective layer raw material and the second protective layer raw material prepared in the step (i), the particle size of the first MgO particles of the first protective layer raw material is smaller than the particle size of the second MgO particles of the second protective layer raw material. And
In the step (ii), the first protective layer raw material and the second protective layer raw material are applied at the same time with the surface of the dielectric layer A to be applied facing downward in the vertical direction. A method for producing a plasma display panel, comprising: forming a first protective layer raw material layer so as to be in contact with the body layer A; and forming a second protective layer raw material layer so as to be in contact with the first protective layer raw material layer .   In the first protective layer material and the second protective layer material prepared in the step (i), the settling rate of the second MgO particles in the second protective layer material is faster than the settling rate of the first MgO particles in the first protective layer material. The method for manufacturing a plasma display panel according to claim 1, wherein the vapor pressure of the second solvent is lower than the vapor pressure of the first solvent.   In the step (ii), the first protective layer raw material and the second protective layer raw material are simultaneously applied by supplying the first protective layer raw material and the second protective layer raw material vertically upward. A method for manufacturing a plasma display panel according to claim 1 or 2. In the step (iii), the protective layer raw material layer having a two-layer structure is subjected to vacuum drying,
The plasma display panel according to any one of claims 1 to 3, wherein the protective layer raw material layer is vacuum-dried in a direction in which the protective layer material layer is positioned below the dielectric layer A in the vertical direction. Method. In the step (iii), the protective layer raw material layer having a two-layer structure is subjected to vacuum drying in two stages,
In the first vacuum drying, the first protective layer raw material layer is dried under a first reduced pressure, and in the second vacuum drying, the second protective layer raw material layer is dried under a second reduced pressure that is further reduced from the first reduced pressure. The method of manufacturing a plasma display panel according to claim 3 or 4, which is dependent on claim 2.