JP2004063247A - Process of manufacture of plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which a black pattern (black matrix) of high definition and a bus electrode are formed in one lot on a front substrate of a plasma display panel (PDP), whereby a PDP can be manufactured with good mass producibility and at a low cost, and a PDP manufactured by the method. <P>SOLUTION: The manufacturing method of the PDP in which a black pattern 10 and a bus electrode 4 are formed in one lot includes (1) a process for forming an insulating black coating layer 20 on a substrate 1, (2) a process for exposing a black pattern portion 10a or the black pattern portion and a bus electrode portion, (3) a process for forming a white system conductive coating layer 21 on the above black coating layer, (4) a process for exposing the bus electrode portion, and (5) a process for firing, after removing the portion other than the exposed portion by developing. The above black coating layer is made of a light-hardened composition containing (A) a black inorganic particulate or preferably tricobalt tetroxide, (B) an organic binder, (C) a photopolymerization monomer, and (D) a photopolymerization initiator. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a PDP in which a black pattern and bus electrodes are collectively formed on a front substrate of a plasma display panel (hereinafter, abbreviated as PDP), and a PDP manufactured by the method.
[0002]
[Prior art]
A PDP is a flat panel display that displays images and information using light emission by plasma discharge, and is classified into a DC type and an AC type according to a panel structure and a driving method. The principle of the color display by the PDP is that a plasma discharge is generated in a cell space (discharge space) between two opposing electrodes formed on a front glass substrate and a rear glass substrate separated by a rib (partition wall), and each cell space is formed. The phosphor formed on the inner surface of the rear glass substrate is excited by ultraviolet rays generated by the discharge of a gas such as He or Xe sealed therein, thereby generating visible light of three primary colors. Each cell space is defined by grid-like ribs in a DC-type PDP, while each cell space is defined by ribs arranged in parallel with a substrate surface in an AC-type PDP. Made with ribs. Hereinafter, a brief description will be given with reference to FIG.
[0003]
FIG. 1 partially shows a structural example of a surface discharge type PDP having a three-electrode structure for full color display. On the lower surface of the front glass substrate 1, a large number of pairs of display electrodes 2a and 2b each including a transparent electrode 3a or 3b for discharging and a bus electrode 4a or 4b for reducing the line resistance of the transparent electrode are provided at a predetermined pitch. It is lined up. On these display electrodes 2a and 2b, a transparent dielectric layer 5 (low-melting glass) for accumulating electric charges is formed by printing and firing, and a protective layer (MgO) 6 is deposited thereon. . The protective layer 6 has a role of protecting a display electrode, maintaining a discharge state, and the like. On the other hand, on the back glass substrate 11, a large number of stripe-shaped ribs (partitions) 12 for dividing discharge spaces and address electrodes (data electrodes) 13 arranged in each discharge space are arranged at a predetermined pitch. I have. Further, phosphor films of three colors of red (14a), blue (14b), and green (14c) are regularly arranged on the inner surface of each discharge space. , One pixel is composed of the phosphor films 14a, 14b, and 14c of the three primary colors of green. Further, on both sides of the pair of display electrodes 2a, 2b forming a discharge space, black patterns (black matrix) 10, 10 in the form of stripes are similarly formed in order to further enhance the contrast of the image.
[0004]
In the PDP having the above-described structure, an AC pulse voltage is applied between the pair of display electrodes 2a and 2b to cause a discharge between the electrodes on the same substrate.
Further, in the PDP having the above-described structure, the ultraviolet light generated by the discharge excites the phosphor films 14a, 14b, and 14c of the rear substrate 11, and the generated visible light is viewed through the transparent electrodes 3a and 3b of the front substrate 1. (Reflection type).
[0005]
In the PDP having such a structure, the bus electrodes 4a and 4b are conventionally formed by patterning by photolithography after depositing three layers of Cr-Cu-Cr by evaporation or sputtering.
However, since the number of steps is large and the cost is high, recently, in order to screen-print a conductive paste such as a silver paste and then sinter it, or to obtain a line width of 150 μm or less, a photosensitive conductive paste is used. A method of applying, exposing through a pattern mask, developing, and then firing is used.
[0006]
Furthermore, in recent years, on the front substrate of the PDP on which the bus electrodes 4a, 4b are formed, in order to improve the contrast of the screen, when forming the bus electrodes, the lower layer (the transparent electrode 3a, 3b) which is on the display side is formed. A black and white two-layered electrode is formed by printing a black paste on the layer to be formed) and printing a white layer of a conductive silver paste thereon. In this case, as the black paste, a resin composition containing a black composite oxide such as a copper-iron type or a copper-chromium type is used.
[0007]
On the other hand, in forming the black pattern (black matrix) 10, it has been attempted to divert a photosensitive resin composition for forming a light-shielding film, which has been conventionally used for forming a black matrix of a CRT display or a liquid crystal display panel. Was. However, in the production of PDP, there is a high-temperature baking step, in which carbon black contained in the photosensitive resin composition for forming a light-shielding film is decomposed, and it has been difficult to form a satisfactory black matrix.
Japanese Patent Application Laid-Open No. 9-160243 discloses a photosensitive resin composition for forming a light-shielding film containing a photopolymerizable compound, a photopolymerization initiator, and a light-shielding material. It has been proposed to use a material composed of another metal oxide such as iron.
[0008]
[Problems to be solved by the invention]
In the PDP having the above structure, an AC pulse voltage is applied between the pair of display electrodes 2a and 2b to discharge between the electrodes on the same substrate, so that the bus electrodes 4a and 4b formed on the front substrate of the PDP are conductive. It is formed by a conductive paste. On the other hand, when the black pattern (black matrix) 10 is formed of a conductive paste, the black pattern inhibits the above-described discharge. Therefore, the black pattern (black matrix) 10 is formed of an essentially electrically insulating paste. As described above, since the bus electrodes 4a and 4b and the black pattern (black matrix) 10 have different required electric properties, they are manufactured by different processes in different materials. Therefore, the number of paste compositions to be prepared and the number of steps are large, which has been a major factor in increasing the production cost and decreasing the productivity.
[0009]
Therefore, the present invention has been made to solve such problems of the prior art, and its basic purpose is to integrate a high-definition black pattern (black matrix) and bus electrodes on the front substrate of the PDP. It is an object of the present invention to provide a method for forming a PDP at a low cost with good mass productivity.
A more specific object of the present invention is to provide a black pattern (black matrix) having sufficient blackness, sufficient interlayer conductivity (interlayer continuity between a transparent electrode and a bus electrode white layer) and blackness on a front substrate of a PDP. And a bus electrode having a black-and-white two-layer structure having a lower-layer (black layer) electrode circuit that can simultaneously satisfy the above conditions.
[0010]
[Means for Solving the Problems]
To achieve the above object, according to the present invention,
(1) a step of forming an insulating black film layer on a substrate;
(2) exposing only the black pattern portion or the black pattern portion and the bus electrode portion;
(3) forming a white conductive coating layer on the black coating layer;
(4) a step of exposing the bus electrode portion, and
(5) A step of baking after development to remove portions other than the exposed portions
A method for manufacturing a plasma display panel, wherein a black pattern and a bus electrode are collectively formed, comprising: (A) black inorganic fine particles, (B) an organic binder, (C) a photopolymerizable monomer, and (D) A method for manufacturing a plasma display panel formed from a photocurable composition containing a photopolymerization initiator, and a plasma display panel manufactured by the method are provided.
In a preferred embodiment, the black inorganic fine particles are cobalt trioxide (Co). ₃ O ₄ ) Is used, and L of the black coating layer is ^* The value is 15 or less.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have conducted intensive studies for realizing the above object, and as a result, it has been thought that it was conventionally necessary to use a conductive paste for the lower layer (black layer) of the bus electrode. A black-and-white two-layer structure formed on a PDP front substrate, as long as a sufficient contrast can be achieved with a thin film thickness, even if such a thin film of a bus electrode black layer does not contain conductive fine particles. Bus electrodes have a sandwich structure in which a black layer is sandwiched between a transparent electrode such as ITO or Nesa and a white layer, thus achieving sufficient interlayer conductivity (interlayer conduction between the transparent electrode and the bus electrode white layer). The present inventors have found that the same black photocurable composition can be used for a black pattern (black matrix) and a black layer of a bus electrode, and have completed the present invention.
That is, the basic feature of the present invention is that the same black-based photocurable composition is used for forming the black pattern and the bus electrode black layer, and the black pattern (black matrix) is formed by a series of exposure, development, and firing steps. The point is that the bus electrodes are formed collectively, whereby mass productivity and cost reduction of the PDP can be achieved.
[0012]
Particularly preferably, cobalt tetroxide (Co) is used as a blackening component. ₃ O ₄ ) A photocurable composition to which black fine particles are added is used. Cobalt tetroxide (Co) as a blackening component ₃ O ₄ ) When black fine particles are added, a dense fired film with a sufficient degree of blackness can be obtained even with a small amount of addition, so that a sufficient contrast can be achieved with a thin film thickness. As a result, in each of the steps of drying, exposure, development, and baking, sufficient interlayer conductivity (between the transparent electrode and the bus electrode white layer) after baking is maintained without deteriorating excellent adhesion to the substrate, resolution, and baking properties. It is possible to form a fired film that can satisfy both the interlayer conduction and blackness. In addition, cobalt trioxide (Co) ₃ O ₄ ) In the case of a photocurable composition in which black fine particles are blended together with a photopolymerizable monomer and a photopolymerization initiator, the reason is not necessarily clear, but the storage stability is extremely excellent, and it can sufficiently cope with mass productivity.
[0013]
Hereinafter, the PDP manufacturing method of the present invention will be described with reference to FIG.
First, as shown in FIG. 2 (A), ITO, SnO is formed in advance by a conventionally known appropriate means such as sputtering, ion plating, chemical vapor deposition, and electrodeposition. ₂ On the front glass substrate 1 on which the transparent electrode 3 has been formed, an insulating black film layer 20 made of a photocurable composition containing black inorganic fine particles as described above is formed.
[0014]
In forming the black film layer 20, when the black-based photocurable composition is previously formed into a film, it may be laminated on a substrate. In the case of a paste-like composition, a screen printing method, A suitable coating method such as a bar coater, a blade coater or the like is applied to the front glass substrate 1 on which the transparent electrode 3 is formed, and then a hot air circulation drying oven, a far infrared drying oven, etc. After drying at 60 to 120 ° C. for about 5 to 40 minutes to evaporate the organic solvent, a tack-free coating film is obtained.
[0015]
Next, as shown in FIG. 2B, a photomask A1 having a predetermined exposure pattern is superimposed on the black coating layer 20, and only the black pattern (black matrix) portion 10a is exposed to light and cured. Alternatively, the black pattern portion and the bus electrode portion are exposed and light-cured (not shown). When only the black pattern portion 10a is exposed and light-cured, the lower layer (black layer) of the bus electrode is exposed simultaneously with the upper layer (white layer) in a subsequent exposure step, and the upper layer (white layer) is exposed. Depending on the film thickness of the layer (layer) portion, the degree of photocuring of the lower layer (black layer) portion may not always be sufficient, but even in this case, portions other than the bus electrode portion can be removed with relatively high precision by a later development step.
[0016]
Next, after the photomask A1 was peeled off, as shown in FIG. 2C, the black fine particles in the composition used for forming the black coating layer were made of a conductive material such as Ag, Au, Al, Pt, or Pd. A paste-like composition similar to the photocurable composition is applied except that the composition is replaced with a powder, and dried in the same manner as above to form a tack-free white conductive film layer 21. In addition, in the case of a dry film which is formed into a film in advance, the white conductive composition may be laminated by thermocompression bonding on a black film layer. Thereafter, as shown in FIG. 2D, a photomask A2 having a predetermined exposure pattern corresponding to the bus electrode pattern is superposed on the white conductive film layer 21 and exposed.
[0017]
In each of the exposure steps shown in FIGS. 2B and 2D, contact exposure and non-contact exposure using a negative mask having a predetermined exposure pattern are possible. As an exposure light source, a halogen lamp, a high-pressure mercury lamp, a laser beam, a metal halide lamp, a black lamp, an electrodeless lamp, or the like is used. The exposure amount is 50 to 1000 mJ / cm ² The degree is preferred.
[0018]
Next, after the photomask A2 is peeled off, development is performed with an alkaline aqueous solution to remove unexposed portions, thereby forming predetermined black patterns and electrode patterns. Then, by firing, as shown in FIG. 2E, a lower electrode film (insulating black fired film layer) 20a and an upper electrode film (white conductive fired film layer) 21a are formed on the transparent electrode 3. And a black pattern (black matrix) 10 are collectively formed. The thickness of the lower electrode film (insulating black fired film layer) 20a is preferably 1.2 μm or less from the viewpoint of interlayer conductivity (interlayer conduction between the transparent electrode 3 and the upper electrode film 21a).
[0019]
As the developing step, a spray method, an immersion method, or the like is used. Examples of the developer include aqueous solutions of metal alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and sodium silicate, and aqueous solutions of amines such as monoethanolamine, diethanolamine, and triethanolamine. A dilute aqueous alkali solution having a concentration of is preferably used, as long as the carboxyl group of the carboxyl group-containing resin in the composition is saponified and the uncured portion (unexposed portion) is removed. However, the present invention is not limited to this. After the development, it is preferable to perform washing with water or acid neutralization in order to remove an unnecessary developer.
[0020]
In the firing step, the substrate after development is subjected to a heat treatment at about 400 to 600 ° C. in air or a nitrogen atmosphere to form a fired film having a predetermined pattern.
[0021]
Next, the photocurable composition used for forming the insulating black film layer will be described. As described above, the black photocurable composition contains (A) black inorganic fine particles, (B) an organic binder, (C) a photopolymerizable monomer, and (D) a photopolymerization initiator. As the black inorganic fine particles (A), cobalt trioxide (Co) ₃ O ₄ ) Is preferably used. This is because, as mentioned above, cobalt tetroxide (Co ₃ O ₄ ) In the case of a photocurable composition to which black fine particles are added, even if the addition amount of cobalt trioxide is small, sufficient blackness (L ^* (A value of 15 or less), and the composition is extremely excellent in storage stability and can sufficiently cope with mass productivity.
[0022]
As the cobalt trioxide black fine particles, it is desirable to use fine particles having a particle size of 5 μm or less, preferably 0.05 μm or more and 5 μm or less. The reason for this is that if the particle size is smaller than 5 μm, a small calcined film can be formed without impairing the adhesion even with a small amount of addition, and sufficient interlayer conductivity (interlayer conduction between the transparent electrode and the bus electrode white layer) can be obtained. This is because it is possible to provide a composition for a lower layer (black layer) electrode film that can simultaneously satisfy black and blackness. On the other hand, if the particle size of the cobalt trioxide black fine particles is larger than 5 μm, the denseness of the fired film is deteriorated, and the blackness of the formed black pattern (black matrix) and the lower electrode film is easily reduced.
[0023]
In addition, the cobalt trioxide black fine particles have a specific surface area of 1.0 to 20 m. ² / G is preferably used. The reason is that the specific surface area is 1.0 m ² If it is less than / g, the accuracy of pattern formation by exposure is reduced, that is, the linearity of the line edge is hardly obtained, and the blackness (L ^* This is because it becomes difficult to obtain a fired film having a value of 15 or less. On the other hand, 20m ² / G, the surface area of the particles becomes too large, and undercutting is likely to occur during development.
[0024]
Cobalt tetroxide (Co ₃ O ₄ The appropriate amount of the black fine particles (A) is 0.1 to 100 parts by mass, preferably 5 to 50 parts by mass per 100 parts by mass of the organic binder (B). The reason for this is that if the blending amount of the black fine particles is less than the above range, sufficient blackness (L ^* (A value of 15 or less) cannot be obtained. On the other hand, if the compounding amount exceeds the above range, the light transmittance deteriorates and the cost increases, which is not preferable.
[0025]
Further, as long as the insulating property of the black film layer (black pattern) to be formed is not impaired, another heat resistant black pigment can be blended in place of part of the above-mentioned cobalt tetroxide. As the heat-resistant black pigment, an inorganic pigment excellent in heat resistance can be widely used. Generally, oxides such as Cr, Co, Ni, Fe, Mn, and Ru and composite oxides correspond to these, and these can be used alone or in combination of two or more.
[0026]
Examples of the organic binder (B) include a resin having a carboxyl group, specifically, a photosensitive resin having a carboxyl group having an ethylenically unsaturated double bond and a carboxyl having no ethylenically unsaturated double bond. Any of the group-containing resins can be used. Examples of the resin (which may be either an oligomer or a polymer) that can be suitably used include the following.
(1) Carboxyl group-containing resin obtained by copolymerizing (a) an unsaturated carboxylic acid and (b) a compound having an unsaturated double bond
(2) Carboxyl group-containing photosensitive resin obtained by adding an ethylenically unsaturated group as a pendant to a copolymer of (a) an unsaturated carboxylic acid and (b) a compound having an unsaturated double bond
(3) Secondary (a) produced by reacting (a) an unsaturated carboxylic acid with a copolymer of (c) a compound having an epoxy group and an unsaturated double bond and (b) a compound having an unsaturated double bond. Carboxyl-containing photosensitive resin obtained by reacting (d) a polybasic acid anhydride with a hydroxyl group of
(4) A copolymer of (e) an acid anhydride having an unsaturated double bond and (b) a compound having an unsaturated double bond is reacted with (f) a compound having a hydroxyl group and an unsaturated double bond. -Containing photosensitive resin obtained by
(5) Carboxyl group-containing photosensitive resin obtained by reacting (g) epoxy compound with (h) unsaturated monocarboxylic acid, and reacting (d) polybasic anhydride with generated secondary hydroxyl group.
(6) (b) an epoxy group of a copolymer of a compound having an unsaturated double bond and glycidyl (meth) acrylate, (i) having one carboxyl group in one molecule, and having an ethylenically unsaturated bond A carboxyl group-containing resin obtained by reacting an organic acid having no secondary hydroxyl group with (d) a polybasic acid anhydride
(7) Carboxyl group-containing resin obtained by reacting (j) hydroxyl group-containing polymer with (d) polybasic acid anhydride
(8) A compound obtained by further reacting (c) a compound having an epoxy group and an unsaturated double bond with a carboxyl group-containing resin obtained by reacting (j) a hydroxyl group-containing polymer with (d) a polybasic acid anhydride. Carboxyl group-containing photosensitive resin
[0027]
The aforementioned carboxyl group-containing photosensitive resin and carboxyl group-containing resin may be used alone or as a mixture, but in any case, they are blended in a total amount of 10 to 80% by mass of the total amount of the composition. Is preferred. If the compounding amount of these polymers is too small than the above range, the distribution of the resin in the film to be formed is likely to be uneven, and it is difficult to obtain sufficient photocurability and photocuring depth, selective exposure, and development. Patterning becomes difficult. On the other hand, if the amount is larger than the above range, the pattern is likely to be distorted and the line width shrinks during firing, which is not preferable.
[0028]
The carboxyl group-containing photosensitive resin and the carboxyl group-containing resin have a weight average molecular weight of 1,000 to 100,000, preferably 5,000 to 70,000, and an acid value of 50 to 250 mgKOH / g, respectively. In the case of a carboxyl group-containing photosensitive resin, those having a double bond equivalent of 350 to 2,000, preferably 400 to 1,500 can be suitably used. If the molecular weight of the resin is lower than 1,000, the adhesion of the film at the time of development is adversely affected. When the acid value is lower than 50 mgKOH / g, the solubility in an alkaline aqueous solution is insufficient and development failure is likely to occur. Part) is not preferred. Further, in the case of a carboxyl group-containing photosensitive resin, if the double bond equivalent of the photosensitive resin is less than 350, residues tend to remain during baking, while if it is more than 2,000, the working margin during development Is small, and a high exposure amount is required at the time of photocuring, which is not preferable.
[0029]
In the black-based photocurable composition, the photopolymerizable monomer (C) is used for promoting the photocurability of the composition and improving the developability. Examples of the photopolymerizable monomer (C) include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polyurethane diacrylate, trimethylolpropane triacrylate, and pentane. Erythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane ethylene oxide modified triacrylate, trimethylolpropane propylene oxide modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate and methacrylates corresponding to the above acrylates; phthalic acid , Adipic acid, maleic acid, itako Mono-, di-, tri- or higher polyesters of acids, succinic acids, trimellitic acids, polybasic acids such as terephthalic acid and hydroxyalkyl (meth) acrylates, but are not limited to specific ones. However, these can be used alone or in combination of two or more. Among these photopolymerizable monomers, polyfunctional monomers having two or more acryloyl groups or methacryloyl groups in one molecule are preferable.
[0030]
An appropriate amount of the photopolymerizable monomer (C) is 20 to 100 parts by mass per 100 parts by mass of the organic binder (carboxyl group-containing photosensitive resin and / or carboxyl group-containing resin) (B). When the amount of the photopolymerizable monomer (C) is less than the above range, it is difficult to obtain a sufficient photocurability of the composition. On the other hand, when the amount exceeds the above range, the surface is harder than the deep part of the film. Since the photocuring of the part is accelerated, uneven curing is likely to occur.
[0031]
Specific examples of the photopolymerization initiator (D) include benzoin and benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, Acetophenones such as 2,2-diethoxy-2-phenylacetophenone and 1,1-dichloroacetophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl- Aminoacetophenones such as 2-dimethylamino-1- (4-morpholinophenyl) -butanone-1; anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone and 1-chloroanthraquinone; 2 Thioxanthones such as 4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone; or xanthones; (2,6-dimethoxybenzoyl) -2,4,4-pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl Phosphine oxides such as -2,4,6-trimethylbenzoylphenyl phosphinate; various peroxides; and these known and commonly used photopolymerization initiators may be used alone or in combination of two or more. In combination it can be used. The mixing ratio of the photopolymerization initiator (D) is suitably from 1 to 30 parts by mass per 100 parts by mass of the organic binder (carboxyl group-containing photosensitive resin and / or carboxyl group-containing resin) (B). Is 5 to 20 parts by mass.
[0032]
The photopolymerization initiator (D) as described above includes N, N-dimethylaminobenzoic acid ethyl ester, N, N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine And other photosensitizers such as tertiary amines.
[0033]
The black photocurable composition may be used, if necessary, by adding other inorganic fine particles (E) such as glass powder, conductive powder, and silica powder having a softening point of 400 to 600 ° C. to the effect of the present invention and the photocurable composition. It can be blended in a quantitative ratio that does not impair the properties of the product.
The glass powder can be added in an amount of 200 parts by mass or less, preferably 150 parts by mass or less per 100 parts by mass of the black inorganic fine particles (A) in order to improve the adhesion of the fired film after firing. The glass powder preferably has a glass transition point (Tg) of 300 to 500 ° C and a glass softening point (Ts) of 400 to 600 ° C. From the viewpoint of resolution, it is preferable to use glass powder having an average particle size of 20 μm or less, preferably 5 μm or less.
[0034]
By adding the above glass powder to the photocurable composition, the film after exposure and development can be easily fired at 600 ° C. or lower. However, in the photocurable composition used in the present invention, an organic binder having good flammability is used, and although the composition is so set that the debinding is completed before the glass powder is melted, the softening point of the glass powder is reduced. When the temperature is lower than 400 ° C., melting occurs at a temperature lower than 400 ° C., so that the organic binder is easily wrapped, and the remaining organic binder is decomposed to easily generate blisters in the composition, which is not preferable.
As the glass powder, an amorphous frit containing lead oxide, bismuth oxide, zinc oxide or the like as a main component can be suitably used.
[0035]
When a large amount of inorganic fine particles or glass powder is blended with the photocurable composition, the resulting composition has poor storage stability, and tends to have poor coating workability due to gelation or reduced fluidity. Therefore, in the photocurable composition used in the present invention, a compound having an effect of complexing or forming a salt with a metal or oxide powder which is a component of inorganic fine particles or glass powder for improving the storage stability of the composition. Is preferably added as a stabilizer. Stabilizers include various inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, and boric acid; various acids such as formic acid, acetic acid, acetoacetic acid, citric acid, stearic acid, maleic acid, fumaric acid, phthalic acid, benzenesulfonic acid, and sulfamic acid. Organic acid; phosphoric acid, phosphorous acid, hypophosphorous acid, methyl phosphate, ethyl phosphate, butyl phosphate, phenyl phosphate, ethyl phosphite, diphenyl phosphite, mono (2-methacryloyloxyethyl) acid Examples include acids such as various phosphate compounds (inorganic phosphoric acid, organic phosphoric acid) such as phosphate, and they can be used alone or in combination of two or more. Such a stabilizer is preferably added at a ratio of 0.1 to 10 parts by mass per 100 parts by mass of the glass powder or the inorganic fine particles (E).
[0036]
In the black photocurable composition used in the present invention, by diluting the composition into a paste, allowing an easy coating process, then drying to form a film, to enable contact exposure, as appropriate Of the organic solvent. Specifically, ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; cellosolve, methyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, Glycol ethers such as propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate Acetates such as ethanol; propanol, ethylene glycol, propylene glycol , Alcohols such as terpineol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, solvent naphtha, and the like, alone or in combination of two or more. Can be used.
[0037]
The black-based photocurable composition further incorporates other additives such as a silicone-based or acrylic-based defoaming / leveling agent, a silane coupling agent for improving the adhesion of the film, and the like, if necessary. You can also. Furthermore, if necessary, known and commonly used antioxidants, thermal polymerization inhibitors for improving thermal stability during storage, metal oxides and silicon oxides as binding components with the substrate during firing And fine particles such as boron oxide.
[0038]
The white photocurable composition used for forming the upper electrode film (white layer) of the bus electrode is the same as the black photocurable composition except that conductive fine particles are used in place of the black inorganic fine particles. The same components (B to D) as in the product are contained in the same mixing ratio, and other components such as an organic solvent and a stabilizer can be added as necessary.
Examples of the conductive fine particles include silver (Ag), gold (Au), nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), lead (Pb), zinc (Zn), and iron (Fe). , Platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), tungsten (W), molybdenum (Mo), etc. and their alloys, as well as oxidation Tin (SnO ₂ ), Indium oxide (In) ₂ O ₃ ), ITO (Indium Tin Oxide) and the like, and these can be used alone or as a mixed powder of two or more kinds.
[0039]
As the shape of the conductive fine particles, various shapes such as a spherical shape, a flake shape, and a dendrite shape can be used, but it is preferable to use a spherical shape in consideration of optical characteristics and dispersibility. The average particle size is preferably 20 μm or less, more preferably 5 μm or less from the viewpoint of resolution. Further, in order to prevent oxidation of the conductive fine particles, improve dispersibility in the composition, and stabilize developability, it is particularly preferable to treat Ag, Ni, and Al with a fatty acid. Fatty acids include oleic acid, linoleic acid, linolenic acid, stearic acid and the like.
[0040]
A suitable amount of the conductive fine particles is 50 to 2,000 parts by mass when the total amount of other components in the composition other than the conductive fine particles is 100 parts by mass. When the compounding amount of the conductive fine particles is less than 50 parts by mass, the line width of the electrode circuit tends to shrink or break, whereas when the compounding amount exceeds 2,000 parts by mass, light transmission is impaired, and Becomes difficult to obtain sufficient photocurability.
Further, in order to improve the strength of the film after firing and the adhesion to the substrate, the above-mentioned glass powder can be added at a ratio of 1 to 30 parts by mass per 100 parts by mass of the conductive fine particles.
[0041]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but it is needless to say that the present invention is not limited to the following Examples. Note that “parts” and “%” are all based on mass unless otherwise specified.
[0042]
Synthesis example
In a flask equipped with a thermometer, a stirrer, a dropping funnel, and a reflux condenser, methyl methacrylate and methacrylic acid were charged at a molar ratio of 0.76: 0.24, dipropylene glycol monomethyl ether was used as a solvent, and azobisisomethyl was used as a catalyst. Butyronitrile was added, and the mixture was stirred at 80 ° C. for 2 to 6 hours under a nitrogen atmosphere to obtain a resin solution. The resin solution was cooled, and methylhydroquinone was used as a polymerization inhibitor, tetrabutylphosphonium bromide was used as a catalyst, and glycidyl methacrylate was added at a temperature of 95 to 105 ° C for 16 hours. An addition reaction was performed at an addition molar ratio of a molar ratio, and after cooling, the mixture was taken out to produce an organic binder A. This resin A had a weight average molecular weight of about 10,000, an acid value of 59 mgKOH / g, and a double bond equivalent of 950. The weight average molecular weight of the obtained copolymer resin was measured by using a pump LC-6AD manufactured by Shimadzu Corporation and a column Shodex (registered trademark) KF-804, KF-803, KF-802 manufactured by Showa Denko KK Was measured by high performance liquid chromatography with three tubes connected.
[0043]
The organic binder A thus obtained was blended at the following composition ratio, stirred by a stirrer, and then kneaded with a three-roll mill to form a paste. In addition, as a glass powder, PbO 60%, B ₂ 0 ₃ 20%, SiO ₂ 15%, Al ₂ 0 ₃ 5% pulverized, thermal expansion coefficient α ₃₀₀ = 70 × 10 ^-7 / ° C, a glass transition point of 445 ° C, and an average particle size of 1.6 µm.
[0044]
White conductive paste for the upper electrode film (white layer) of the bus electrode;
Organic binder A 100.0 parts
Pentaerythritol triacrylate 50.0 parts
2-benzyl-2-dimethylamino-1-
(4-morpholinophenyl) butan-1-one 5.0 parts
Dipropylene glycol monomethyl ether 80.0 parts
Silver powder 450.0 parts
Glass powder 22.0 parts
Phosphate ester 1.0 part
[0045]
Black paste for black pattern and lower electrode film (black layer) of bus electrode:
Organic binder A 100.0 parts
Pentaerythritol triacrylate 50.0 parts
2-benzyl-2-dimethylamino-1-
(4-morpholinophenyl) butan-1-one 5.0 parts
Dipropylene glycol monomethyl ether 80.0 parts
Cobalt tetroxide (Co ₃ O ₄ 40.0 parts
(Particle size 0.20 μm, specific surface area 4.9 m ² / G)
[0046]
The black paste prepared as described above is applied to the entire surface of the glass substrate on which the ITO transparent electrode has been formed in advance using a 200-mesh polyester screen, and dried at about 90 ° C. for 20 minutes in a hot-air circulation drying oven. Thus, a tack-free coating film was obtained (formation of a black coating layer).
Next, a photomask having a predetermined exposure pattern was superimposed on the formed black film layer, and a metal halide lamp was used as a light source, and the integrated light amount was 400 mJ / cm. ² Then, the black pattern (black matrix) portion and the bus electrode portion were exposed to light and cured.
Next, after the photomask was peeled off, the white conductive paste prepared as described above was applied and dried at about 90 ° C. for 20 minutes in a hot-air circulation drying oven to obtain a tack-free coating film (white). Formation of a system conductive film layer).
[0047]
Thereafter, a photomask having a predetermined exposure pattern corresponding to the bus electrode pattern is superimposed on the formed white conductive film layer, and the integrated light amount is 400 mJ / cm. ² Exposure was performed so that
Next, after removing the photomask, 0.5% Na at a liquid temperature of 30 ° C. ₂ CO ₃ Development was carried out using an aqueous solution, followed by washing with water. Finally, the temperature was raised at a rate of 5 ° C./min in an air atmosphere and baked at a temperature of 550 ° C. for 30 minutes to produce a PDP front substrate on which a bus electrode and a black pattern (black matrix) were collectively formed.
[0048]
A tester was applied to the upper (white) electrode film of the bus electrode and the ITO transparent electrode of the fired film obtained in this manner, and conduction was confirmed. As a result, good conductivity was confirmed.
Further, when the obtained fired film was visually observed from the glass side and the color tone was confirmed, the lower electrode film of the bus electrode and the black pattern (black matrix) were black. Further, L was measured using a colorimeter (CR-221, manufactured by Minolta Camera Co., Ltd.) using a test piece whose color tone was confirmed after firing. ^* a ^* b ^* When the value of the color system was measured according to JIS-Z-8729, the index L representing the lightness was obtained. ^* The value was 7.8 (this L ^* The smaller the value, the better the blackness).
When 300 g of the black paste was placed in a closed container and left at 30 ° C. for one month, the state was confirmed. As a result, no change occurred without gelation, and the stability was excellent.
In addition, for each of the above-mentioned evaluation pastes, the line shape after development, the line shape after baking, and the adhesion were evaluated, but no problem was found.
[0049]
【The invention's effect】
As described above, according to the method of the present invention, a high-definition black pattern (black matrix) and bus electrodes can be collectively formed on the front substrate of a PDP, whereby a PDP can be manufactured with good mass productivity and at low cost.
In particular, when a photocurable composition containing cobalt tetroxide as the black inorganic fine particles is used, drying, exposure, development, and sintering are performed because storage stability is excellent and sufficient contrast can be obtained with a thin film thickness. In each of the above steps, a black pattern (black matrix) having a sufficient blackness and a sufficient interlayer conductivity (a transparent electrode and a transparent electrode) are formed on the front substrate of the PDP without deteriorating the excellent adhesion, resolution, and baking properties to the substrate. A bus electrode having a black-and-white two-layer structure having a lower (black layer) electrode film capable of simultaneously satisfying blackness and interlayer conduction with the bus electrode white layer can be formed collectively in a series of steps.
[Brief description of the drawings]
FIG. 1 is a partially exploded perspective view of a surface discharge type AC PDP.
FIG. 2 is a schematic partial cross-sectional view showing a process example of a method of manufacturing a front substrate of a PDP according to the present invention.
[Explanation of symbols]
1 Front glass substrate
2a, 2b Display electrode
3,3a, 3b transparent electrode
4,4a, 4b bus electrode
5 Transparent dielectric layer
6 Protective layer
10. Black pattern (black matrix)
11 Back glass substrate
12 ribs
13 Address electrode
14a, 14b, 14c phosphor film
20 Insulating black film layer
21 White conductive film layer
20a Lower electrode film (insulating black fired film layer)
21a Upper electrode film (white conductive fired film layer)

Claims (11)

(1) a step of forming an insulating black film layer on a substrate;
(2) exposing only the black pattern portion or the black pattern portion and the bus electrode portion;
(3) forming a white conductive coating layer on the black coating layer;
(4) A method of manufacturing a plasma display panel for collectively forming a black pattern and a bus electrode, including a step of exposing a bus electrode portion and a step of (5) developing and removing a portion other than the exposed portion, followed by baking. The black coating layer is formed from a photocurable composition containing (A) black inorganic fine particles, (B) an organic binder, (C) a photopolymerizable monomer, and (D) a photopolymerization initiator. A method for manufacturing a plasma display panel, comprising: The method according to claim 1, wherein cobalt trioxide is used as the black inorganic fine particles (A). 3. The method according to claim 2, wherein the cobalt trioxide has a specific surface area of 1.0 to ²⁰ m < ² > / g and a particle size of 5 [mu] m or less. 4. The method according to claim 2, wherein another part of the cobalt trioxide is replaced with another heat resistant black pigment. 5. The organic binder (B) is a carboxyl group-containing photosensitive resin or a carboxyl group-containing resin having a weight average molecular weight of 1,000 to 100,000 and an acid value of 50 to 250 mgKOH / g. A method according to any one of the preceding claims. The organic binder (B) is (1) a carboxyl group-containing resin obtained by copolymerizing (a) an unsaturated carboxylic acid and (b) a compound having an unsaturated double bond; A carboxyl group-containing photosensitive resin obtained by adding an ethylenically unsaturated group as a pendant to a copolymer of a saturated carboxylic acid and (b) a compound having an unsaturated double bond; (3) (c) an epoxy group; The copolymer of the compound having an unsaturated double bond and (b) a compound having an unsaturated double bond is reacted with (a) an unsaturated carboxylic acid, and the resulting secondary hydroxyl group is converted into (d) a polybasic acid. A carboxyl group-containing photosensitive resin obtained by reacting an anhydride, (4) a copolymer of (e) an acid anhydride having an unsaturated double bond and (b) a copolymer of a compound having an unsaturated double bond, f) hydroxyl and unsaturated double (5) (g) an epoxy compound and (h) an unsaturated monocarboxylic acid, which are obtained by reacting a compound having a bond with a carboxyl group-containing photosensitive resin. A carboxyl group-containing photosensitive resin obtained by reacting an acid anhydride; (6) (b) an epoxy group of a copolymer of a compound having an unsaturated double bond and glycidyl (meth) acrylate; A carboxyl group-containing resin obtained by reacting an organic acid having one carboxyl group therein and having no ethylenically unsaturated bond, and reacting the resulting secondary hydroxyl group with (d) a polybasic acid anhydride; (7) a carboxyl group-containing resin obtained by reacting (d) a polybasic acid anhydride with (j) a hydroxyl group-containing polymer, and (8) a (d) polybasic acid anhydride with a (j) (j) hydroxyl group-containing polymer. Get (C) at least one resin selected from the group consisting of a carboxyl group-containing photosensitive resin obtained by further reacting a compound having an epoxy group and an unsaturated double bond with the carboxyl group-containing resin. The method according to any one of claims 1 to 5, wherein The amount of each component in the photocurable composition for forming the black coating layer is 100 parts by mass of the organic binder (B), and the amount of the black fine particles (A) is 0.1 to 100 parts by mass. The compounding amount of the photopolymerizable monomer (C) is 20 to 100 parts by mass, and the compounding amount of the photopolymerization initiator (D) is 1 to 30 parts by mass. The method described in. The photocurable composition for forming the black coating layer further comprises at least one other inorganic fine particle selected from the group consisting of glass powder, conductive powder and silica powder. The method according to any one of claims 1 to 7. The photocurable composition for forming the black coating layer further contains at least one acid selected from the group consisting of inorganic acids, organic acids, and phosphoric acid compounds as a stabilizer. 9. The method according to 8. The photocurable composition for forming the black coating layer, except that the composition used to form the white conductive coating layer, except that the conductive fine particles are used in place of the black inorganic fine particles. 10. A method according to any one of the preceding claims, containing similar components. A plasma display panel produced by the method according to any one of claims 1 to 10, wherein the L ^* value of the black coating layer is 15 or less.

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