JPH08321257A - Plasma display panel barrier forming application liquid, its manufacture, and barrier forming method - Google Patents

Abstract

PURPOSE: To form a defect-free barrier forming layer in one run of operation by preparing a coating liquid for formation of PDP barrier from a glass powder having a low melting point, fire-resistant filler, binder resin, and solvent, wherein the boiling point of the solvent should be below 150 deg.C at a normal pressure. CONSTITUTION: A small quantity of solvent having high boiling point such as di. 2-ethylhexylpthalate is added to a solvent having a low boiling point such as methyl isobutyl ketone, in which a binder resin such as ethyl cellulose is dissolved, and thereto a plasticizer such as polyoxyethylene alkyl phosphate (ester) is added so that a vehicle is produced. and to this vehicle, glass frit, crushed brown alumina, and black pigment are added in despersion so that a coating liquid is provided. An electrode 2 and a dielectric substance layer 3 are formed on a glass board 1 on the back surface of a plasma display panel(PDP), and the coating liquid is cast to form a barrier forming layer 4. Thereover a resist pattern 7 is formed. followed by sandblasting and baking, and a defect-free barrier 8 in good shape is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid for forming a barrier of a plasma display panel (hereinafter referred to as PDP), a method for producing the same, and a method for forming a barrier for a PDP.

[0002]

2. Description of the Related Art Generally, a PDP which is a gas discharge panel
Has a large number of cells as minute discharge spaces sandwiched between two substrates, and discharges each cell to emit light, or emits ultraviolet rays to cause a phosphor to emit light. Barriers are provided between these minute cells in order to prevent mutual interference between the cells and to keep the distance between both substrates constant. And conventionally, in the formation of this barrier,
Patterning by screen printing using a barrier forming paste has been generally performed.

By the way, in the above-mentioned PDP, in order to make the discharge space as large as possible and to obtain high-luminance light emission, a barrier wall having a vertical wall and a narrow width and a high height is required. Especially in a high-definition display, for example, a height of 10
A barrier with a high aspect ratio, such as a width of 30 to 50 μm, is required for 0 μm. However, in the above-mentioned screen printing, since the film thickness that can be formed by one printing is several tens of μm at most, it is necessary to repeat printing and drying a large number of times, generally 10 times or more, resulting in poor productivity. There is a point. In addition, since the coating film formed by screen printing has a dented peripheral portion and a convex shape, when overprinting a large number of times, there is the problem that sagging accumulates and the bottom portion expands. There was a limit. Further, in screen printing, there is a problem in that the pitch accuracy is limited due to the distortion of the printing plate, and it is not possible to cope with an increase in the size of the panel.

As a method capable of solving such a problem,
A barrier formation method using a subtractive method has been proposed (Electronic Materials, 1983, No. 11, p13).
8). That is, this is a method in which after forming the barrier forming layer, a subtractive resist pattern is formed on the upper surface by printing or photolithography, and the barrier forming material in the opening of the resist pattern is removed. Among them, what is called a sandblasting method, in which fine particles mixed with a compressed gas are jetted at high speed to physically perform etching, is particularly expected. By using this sandblasting method, it is possible to process the barrier material into a desired shape in which the wall surface is cut vertically and the width is narrow and the height is high. Further, by adopting a photolithography process for patterning the resist, it is possible to increase the pattern accuracy, so that it is possible to cope with an increase in size.

In order to form a barrier by the sandblast method, first, a step of forming an unfired barrier forming layer on a glass substrate or the like with a uniform thickness of about 100 to 200 μm is necessary. Conventionally, in this step, a method of repeating solid printing a large number of times by a screen printing method or a method of casting with a blade coater or the like and applying it at once has been used. The coating solution used here was manufactured by kneading with a roll mill using a high boiling point solvent such as terpineol, butyl carbitol acetate and the like.

[0006]

However, when the barrier forming layer is formed by the screen printing method, the number of times (usually 5 times) is required.
Since solid printing is also performed 10 to 10 times) and drying is repeated each time, there is a problem that productivity is poor, and there is a problem that irregularities are generated on the coating film surface due to gauze. Therefore, it is considered preferable to cast the coating liquid with a blade coater or the like to form the barrier forming layer once, but in this case, a new problem occurs in which various defects occur during the drying process. Even if these defects can be avoided, the drying requires a long time and a lot of energy, and further, the drying device requires a high degree of control. The defect mentioned here occurs specifically as follows.

(1) The hot air necessary for removing the solvent in the coating liquid causes the coating film to flow, resulting in uneven thickness of the barrier forming layer. (2) Since a high boiling point solvent is used for the coating liquid, it is necessary to heat at a high temperature of 100 ° C. or higher from the initial drying. However, when the glass substrate after casting is put into an atmosphere of 100 ° C. or higher, the temperature of the cast film rises from the upper part due to the heat capacity of the glass substrate, and the vicinity of the surface is dried and skinned first. Will end up. If such a skinning phenomenon occurs, the inside of the cast film will be dried extremely slowly,
It causes defects such as dust wrinkles, craters due to boiling water or cracks caused by them. (3) When the coating liquid is dried by heating with a hot plate, it is possible to heat from the lower part of the cast film, but the flatness of the glass substrate is not necessarily good, so contact with the hot plate is partial. Therefore, a difference occurs in heat conduction, causing unevenness.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a barrier forming coating for a PDP, which can form a defect-free barrier forming layer at one time. Another object of the present invention is to provide a liquid and a method for producing the same, and a method for forming a PDP barrier using the coating liquid.

[0009]

In order to achieve the above object, a barrier forming coating liquid according to the present invention is used for forming a barrier of a PDP containing at least a low melting point glass powder, a refractory filler, a binder resin and a solvent. The coating liquid is characterized in that the boiling point of the solvent is 150 ° C. or lower at normal pressure.

As the low melting point glass, the main component is Pb.
Al ₂ O ₃ , B ₂ O ₃ , in order to have the effect of preventing the phase separation of glass, adjust the softening point, and adjust the coefficient of thermal expansion to the glass substrate, containing O by 50% or more. S
Those containing iO ₂ , MgO, CaO, SrO, BaO, etc. are generally used.

The refractory filler is 500 to 600.
Ceramic powders such as alumina, magnesia, calcia, cordierite, silica, mullite, and zircon that can be widely used and do not soften at a firing temperature of about 0 ° C. are preferably used.

In order to reduce the reflection of external light from the PDP and increase the practical contrast, the barrier is often required to be black. In this case, as a refractory black pigment,
Co-Cr-Fe, Co-Mn-Fe, Co-Fe-M
n-Al, Co-Ni-Cr-Fe, Co-Ni-Mn
-Cr-Fe, Co-Ni-Al-Cr-Fe, Co-
A pigment such as Mn-Al-Cr-Fe-Si is used.
On the other hand, in order to effectively guide the light emission of the phosphor to the front surface of the panel,
Conversely, it may be better to whiten the barrier. In this case, titania or the like is used as the refractory white pigment.

The content of low melting point glass in the inorganic component is 30.
˜70 wt% is preferred. If the amount is too large, the shape retention due to firing becomes difficult. In addition, debinding property is impaired and denseness is deteriorated, which is not preferable. On the contrary, if it is too small,
The gap between the refractory fillers cannot be filled sufficiently, the denseness deteriorates, and at the same time the mechanical strength after firing decreases.
Chips occur when sealing panels.

The binder resin must be burned / decomposed / vaporized at low temperatures so that no carbides remain in the barrier,
Cellulose resins such as ethyl cellulose, methyl cellulose, nitrocellulose, cellulose acetate, cellulose propionate, and cellulose butyrate, or methyl methacrylate, ethyl methacrylate, normal butyl methacrylate, isobutyl methacrylate,
An acrylic resin made of a polymer such as isopropyl methacrylate, 2-ethylmethyl methacrylate, 2-hydroxyethyl methacrylate, or a copolymer thereof is preferably used.

Further, as an additive, a plasticizer, a surfactant, an antifoaming agent, an antioxidant and the like are used as required.
Among them, as the plasticizer, phthalic acid esters, sebacic acid esters, phosphoric acid esters, adipic acid esters, glycolic acid esters, citric acid esters and the like are generally used. If the addition rate of the plasticizer is too high, the flexibility of the resin increases and the grinding speed by sandblasting slows down. Therefore, the addition amount of the plasticizer is preferably 1/5 or less by weight ratio with respect to the resin amount.

As described above, the present invention requires that the boiling point of the solvent is 150 ° C. or lower at normal pressure. The solvent having a boiling point of 150 ° C. or lower is preferably a good solvent for the binder resin used, and acetone,
Ketones such as methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone and diisobutyl ketone, hydrocarbons such as hexane, cyclohexane, benzene, toluene and xylene, methyl acetate, ethyl acetate,
Isopropyl acetate, normal propyl acetate, isobutyl acetate, normal butyl acetate, normal pentyl acetate, isopentyl acetate and other esters, methanol, ethanol, isopyranol, normal propanol, normal butanol, isobutanol, toluene, xylol and other alcohols, methylene Chloride, chloroform, 1,2
Examples include chlorinated hydrocarbons such as dichloroethane and 1,1,1-trichloroethane, ethers such as ethyl ether and 1,4-dioxane, and glycol derivatives such as 2-methoxyethanol and 2-ethoxyethanol. Further, a small amount of a solvent having a higher boiling point may be added for the purpose of adjusting rheological properties, drying properties, dispersion stability, etc. of the coating liquid.

When the boiling point of the solvent exceeds 150 ° C. under normal pressure, it is not possible to sufficiently avoid unevenness in drying when the coating liquid is applied, and it is also impossible to shorten the drying time. From the viewpoint of shortening the drying time, the lower the boiling point of the solvent, the better, but if it is too low, the amount of volatilization increases in the defoaming process and the supplying process of the coating liquid, and the composition of the coating liquid should be stabilized. The problem arises that it becomes difficult. When a method such as reverse roll coating in which the coating head is open is used as the coating method, it is necessary to suppress the volatilization of the solvent in the head portion, so it is preferable to raise the boiling point of the solvent.

The selection of the solvent is carried out mainly considering the volatility of the solvent and the solubility of the binder resin used. If the solubility of the solvent in the binder resin is low, the viscosity of the coating liquid will be high even if the solid content ratio is the same, and the suitability for coating will be deteriorated.

If the content of the solvent is too low, the viscosity of the coating solution becomes too high, it becomes difficult to remove air bubbles in the coating solution, and the smoothness of the coated surface is deteriorated due to poor leveling. It is not preferable because it causes a problem. On the contrary, when it is too much, the settling of dispersed particles becomes fast and it becomes difficult to stabilize the composition of the coating liquid, and it takes a lot of energy and time for drying. Is not preferred, and is preferably 25 to 50% by weight.

The binder resin in the coating liquid contains a resin in the component excluding the solvent in order to enhance the grindability in sandblasting, regardless of whether the binder resin is mainly composed of a cellulose resin or an acrylic resin. The rate is preferably 1 to 4% by weight. If the amount is too small, the stability of the coating liquid may be deteriorated, and cracks may be easily generated in the drying process.

Next, the method for producing the coating liquid according to the present invention is as follows.
A mixture containing at least a low-melting glass powder, a refractory filler, a binder resin, and a solvent, in which the boiling point of the solvent is 150 ° C. or less at normal pressure, is dispersed and prepared by a ball mill.

That is, after a binder resin is dissolved in a solvent and an additive is added if necessary, a mixture (inorganic component (low melting glass powder and refractory filler)) is mixed with a solution (vehicle) to prepare a mixture. This mixture is dispersed in a ball mill and blended, and in order to avoid mixing of impurities, a ceramic ball is used, and more preferably, a ball mill whose inner wall is coated with ceramic or plastic is used. Then, after dispersion and blending, defoaming is performed under reduced pressure using a vacuum stirrer.

Next, in the method for forming a barrier of a PDP according to the present invention, the above coating solution is solidly coated on an object to form a barrier forming layer, and then a resist pattern provided on the barrier forming layer. The method is characterized by including a step of patterning the barrier forming layer by performing a sandblasting process via.

As the coating method of the coating liquid, blade coating, comma coating, reverse roll coating, spray coating, gun coating, extrusion coating, lip coating and the like are preferably used. The application is generally performed on a glass substrate, but in some cases, it is also possible to apply it on a film and transfer it to the glass substrate. It is also possible to form a barrier forming layer and a resist layer on the film side and transfer them simultaneously to the glass substrate.

The resist pattern can be directly formed by printing, but in the case of performing high-precision processing in a large area, a photoresist is used as a resist material and a photolithography method is used. preferable. As the photoresist, either a dry film resist or a liquid resist can be used, and they can be used in combination. As the resist, there are an alkali developing type, a water developing type and an organic solvent developing type, but an alkali developing type or a water developing type which has a small effect on the environment is preferably used.

The resist stripping performed after sandblasting is preferably performed using a stripping solution. A method of spraying a stripping solution from above the panel is preferably carried out to obtain stability in mass production. Further, the baking process after the resist is peeled off is suitably performed in an oxidizing atmosphere at a peak temperature of 500 to 600 ° C.

[0027]

Since the coating liquid of the present invention has a low boiling point of the solvent and high volatility, it requires less energy for drying and can be dried in a short time after coating. Further, in the initial drying after application, strong hot air is not required, and unevenness due to the influence of wind can be avoided. Further, since the solvent can be volatilized at room temperature or with slight heating, the skinning phenomenon due to the difference in the vertical temperature distribution in the coating film does not occur.

[0028]

【Example】

Example 1 A barrier forming coating liquid having the following composition A (% by weight) was prepared. Specifically, a vehicle was prepared by first dissolving a binder resin in a solvent obtained by adding a small amount of a high boiling point solvent to a low boiling point solvent, and then adding a plasticizer thereto. Then, a mixture was prepared by mixing the vehicle and the inorganic powders of ~, and the mixture was dispersed and prepared by stirring for 15 hours with a ball mill (10 mmφ alumina balls, polypropylene pot).
Subsequently, defoaming was performed under reduced pressure with a vacuum stirrer to obtain a coating liquid.

<Composition A> Methyl isobutyl ketone (boiling point: 115 ° C.) 25.4 Di-2-ethylhexyl phthalate 0.2 Ethyl cellulose (Ethcel std. 20, manufactured by Nisshin Kasei) 1.5 Polyoxyethylene alkyl phosphate ester 0.1 (Kao, Estamit TR-09) Glass frit (Nippon Electric Glass, GA-21) 44.7 Pulverized brown alumina (Fujimi Abrasives Co., Ltd., WA # 8000) 11.9 Black pigment (Root special chemistry) Made, heat resistant black 4200) 16.2

Then, a barrier was formed on the back plate of the PDP using the above coating solution. This barrier formation procedure will be described with reference to FIG.

First, as shown in FIG. 1A, an electrode 2 is formed on a substrate 1 made of glass, and a dielectric layer 3 is formed thereon.
After forming, the coating liquid of the above composition A was cast on the dielectric layer 3 with a reverse roll coater. Then, warm air at 40 ° C. is applied with a gentle breeze around 0.3 m / sec for 15 minutes.
Apply for 1 minute, then warm air at 70 ℃ at a wind speed of 0.6m / sec for 1
0 minutes, then warm air at 120 ° C at a wind speed of 5 m / sec for 10 minutes
Apply for minutes to dry. As a result, the average film thickness is 160
The barrier-forming layer 4 having a thickness of μm and high film thickness uniformity and good surface smoothness was obtained.

Then, the substrate 1 is heated to 80 ° C.
As shown in (b), a dry film resist 5 was laminated. The dry film resist 5 used is “NCP225” manufactured by Nippon Synthetic Chemical Industry. Next, FIG.
As shown in (c), line width 80 μm, pitch 220 μm
Exposure was performed with ultraviolet rays through the line pattern mask 6. The exposure condition is an intensity of 200 μW at 364 nm.
/ Cm ² , and the irradiation dose is 120 mJ / cm ² . After exposure,
Spray development was performed with a 1 wt% aqueous solution of sodium carbonate at a liquid temperature of 30 ° C. Through the above steps, a sandblast resist pattern 7 having a line width of 80 μm and a pitch of 220 μm was obtained as shown in FIG.

Subsequently, after drying / aging at 50 ° C. for 2 hours, unnecessary portions were removed by sandblasting as shown in FIG. 2 (a). In this case, the distance between the nozzle and the substrate 1 was set to 10 cm, and the sand blasting treatment was performed using brown fused alumina # 1000 as the abrasive at a jet pressure of 3 kg / cm ² .

After finishing the sandblasting process, as shown in FIG.
As shown in (b), the resist pattern 7 was peeled off using a peeling solution. Specifically, a 2.0 w% aqueous solution of sodium hydroxide was used as a stripping solution, and spray stripping was performed at 30 ° C. Then, after washing with water, it was dried in an oven at 80 ° C. for 15 minutes. Then, peak temperature 550 ℃
Then, the barrier-forming material was bound as shown in FIG. As a result, there was no defect such as chipping, and a good barrier 8 having a high surface smoothness was formed.

Example 2 A barrier forming coating solution having the following composition B (% by weight) was prepared in the same manner as in Example 1. That is, low boiling point solvent, high boiling point solvent, binder resin, after preparing a vehicle with a plasticizer, a mixture of this vehicle and an inorganic powder was dispersed and blended in the same ball mill as in the example, Subsequently, defoaming was performed under reduced pressure with a vacuum stirrer to obtain a coating liquid.

<Composition B> Toluene (boiling point: 110 ° C.) 29.0 Di-2-ethylhexyl phthalate 0.2 Polymethyl methacrylate 1.5 (Rohm and Haas Japan, Paraloid B-82) Polyoxyethylene Alkyl phosphate ester 0.1 (manufactured by Kao, Estamit TR-09) Glass frit (manufactured by Nippon Electric Glass, GA-21) 42.5 Grinded brown alumina (manufactured by Fujimi Abrasive Industry Co., Ltd., WA # 8000) 11.3 Black pigment (Nippon Specialty Chemicals, heat resistant black 4200) 15.4

Then, a barrier was formed on the back plate of the PDP by the same process as in Example 1 using the coating solution of the composition B. Also in the case of this example, there was no defect such as chipping, and a good barrier having a high surface smoothness could be formed.

[0038]

As described above, the barrier-forming coating liquid of the present invention uses a solvent mainly having a boiling point of 150 ° C. or less at normal pressure. After coating, the time required for the drying process is short, and since strong hot air is not required in the initial drying, unevenness of the coating film due to the influence of wind can be avoided, and the vertical temperature distribution in the coating film There is no skinning phenomenon due to the difference,
Therefore, a defect-free barrier formation layer can be formed once.

Further, in the barrier forming method of the present invention,
Using a coating liquid containing a solvent mainly composed of a solvent having a low boiling point as described above, a barrier-forming layer is formed by solid-coating this, so that a defect-free barrier-forming layer can be easily obtained.
The productivity is improved as compared with overprinting by screen printing to obtain a predetermined film thickness, and by sandblasting, it is possible to form a barrier having a good shape without defects.

[Brief description of drawings]

FIG. 1 is a process drawing of the first half showing an embodiment of a barrier forming method.

FIG. 2 is a process diagram of the latter half of FIG.

[Explanation of symbols]

 1 Substrate 2 Electrode 3 Dielectric Layer 4 Barrier Forming Layer 5 Resist 6 Mask 7 Resist Pattern 8 Barrier

Claims (6)

[Claims] 1. A coating liquid for forming a barrier of a plasma display panel, which comprises at least a low-melting glass powder, a refractory filler, a binder resin and a solvent, wherein the boiling point of the solvent is 150 ° C. or lower at normal pressure. A characteristic coating liquid for barrier formation in plasma display panels. 2. The binder resin is mainly composed of a cellulosic resin or an acrylic resin, and the resin content of the components excluding the solvent is 1 to 4% by weight. 1. A coating liquid for forming a barrier for a plasma display panel according to 1. 3. A ball mill is used to disperse and blend a mixture containing at least a low-melting glass powder, a refractory filler, a binder resin, and a solvent, the boiling point of the solvent being 150 ° C. or less at normal pressure. A method for producing a coating liquid for forming a barrier of a plasma display panel, the method comprising: 4. The binder resin in the mixture is mainly composed of a cellulosic resin or an acrylic resin, and the resin content of the components excluding the solvent is 1 to 4% by weight. The method for producing a coating liquid for forming a barrier of a plasma display panel according to claim 3. 5. A method for forming a barrier of a plasma display panel, which uses a coating liquid containing at least a low-melting glass powder, a refractory filler, a binder resin and a solvent, and the boiling point of the solvent is 150 ° C. or lower at atmospheric pressure. That is, the coating liquid is solidly coated on an object to form a barrier forming layer, and then the barrier forming layer is patterned by sandblasting through a resist pattern provided on the barrier forming layer. A method of forming a barrier in a plasma display panel, comprising: 6. A coating liquid in which the binder resin is mainly a cellulose resin or an acrylic resin, and the resin content of the components excluding the solvent is 1 to 4% by weight. The method for forming a barrier of a plasma display panel according to claim 5.