JP2004006422A - Transferring film for forming dielectric layer of plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a plasma display panel including a novel forming process capable of efficiently forming a dielectric layer with a large film thickness. <P>SOLUTION: The manufacturing method includes a process of forming a film-forming material layer by coating a paste composition containing an acrylic ester system resin and a solvent on a support film, transferring the film-forming material layer formed on the support film onto the surface of a glass substrate with electrodes fixed, and forming a dielectric layer on the surface of the glass substrate by baking the film-forming material layer transferred. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method for manufacturing a plasma display panel and a transfer film used therefor, and more particularly, to a method for manufacturing a plasma display panel and a transfer film including a novel process for forming a dielectric layer on a glass substrate. .

Recently, a plasma display is attracting attention as a flat fluorescent display. FIG. 1 is a schematic diagram showing a cross-sectional shape of an AC type plasma display panel (hereinafter, also referred to as “PDP”). In FIG. 1, reference numerals 1 and 2 denote glass substrates arranged opposite to each other, and reference numeral 3 denotes a partition. A cell is defined by the glass substrate 1, the glass substrate 2 and the partition 3. 4 is a bus electrode fixed to the glass substrate 1, 5 is an address electrode fixed to the glass substrate 2, 6 is a fluorescent substance held in a cell, and 7 is a surface of the glass substrate 1 so as to cover the bus electrode 4. The dielectric layer 8 is a protective layer made of, for example, magnesium oxide. The dielectric layer 7 is formed of a glass sintered body and has a thickness of, for example, 20 to 50 μm.

As a method for forming the dielectric layer 7, a paste-like composition containing glass powder is prepared, and the paste-like composition is applied to the surface of the glass substrate 1 by a screen printing method and dried to form a film-forming material layer. A method is known in which an organic substance is removed by baking this film forming material layer and then sintering the glass powder.

Here, the thickness of the film-forming material layer formed on the glass substrate 1 is set to be equal to the thickness of the dielectric layer 7 to be formed in consideration of the reduction in the film thickness accompanying the removal of the organic substance in the firing step. For example, in order to make the thickness of the dielectric layer 7 20 to 50 μm, a film forming material layer having a thickness of about 30 to 70 μm is formed. There is a need.

On the other hand, when the paste composition containing the glass powder is applied by a screen printing method, the thickness of the coating film formed by one application treatment is about 15 to 25 μm. Therefore, in order to make the film-forming material layer have a predetermined thickness, it is necessary to repeatedly apply the paste composition to the surface of the glass substrate a plurality of times (for example, 2 to 5 times).

(1) The operation of repeatedly applying the paste composition a plurality of times by the screen printing method (multiple printing) is complicated and poor in workability. In addition, it is necessary to confirm the dispersion state of the constituent components every time the paste-like composition is applied, and when dispersion failure such as precipitation of glass powder occurs, redispersion processing must be performed. Therefore, the conventional method of forming a dielectric layer through such a complicated coating process has a problem from the viewpoint of PDP production efficiency, and has become a particularly significant problem with an increase in the size of a display panel.
(2) When the film forming material layer is formed by multiple printing using a screen printing method, the dielectric layer formed by firing the film forming material layer has a uniform thickness (for example, a tolerance of ± 5%). ). This is because it is difficult to uniformly apply the paste-like composition to the surface of the glass substrate in the multiple printing by the screen printing method, and the larger the application area (panel size) and the larger the number of application times. The greater the thickness of the dielectric layer, the greater the degree of variation. Then, in a panel material (a glass substrate having the dielectric layer) obtained through a coating process by multiple printing, in the surface thereof, a variation occurs in dielectric characteristics due to a variation in film thickness. This causes display defects (luminance unevenness) in the PDP.
(3) In the screen printing method, a very small amount of air may be entrained by the paste composition passing through the screen, and may remain as bubbles in the film forming material layer. When the film-forming material layer containing bubbles is fired, pinholes and cracks occur in the formed dielectric layer. Furthermore, during the formation of the (n + 1) th layer coating film, the nth layer coating film is easily damaged by squeegees, which may cause cracks in the dielectric layer. The dielectric layer whose insulation property has been destroyed by pinholes or cracks cannot exhibit the desired dielectric properties.
(4) In the screen printing method, the mesh shape of the screen plate may be transferred to the surface of the film forming material layer, and the dielectric layer formed by firing such a film forming material layer has a smooth surface. It is inferior in sex.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a PDP including a novel forming process capable of efficiently forming a dielectric layer having a large thickness. It is to provide a manufacturing method of. A second object of the present invention is to provide a method of manufacturing a PDP including a novel forming step capable of efficiently forming a dielectric layer required for a large-sized panel. A third object of the present invention is to provide a method of manufacturing a PDP having a dielectric layer having excellent film thickness uniformity. A fourth object of the present invention is to provide a method for manufacturing a PDP having a highly reliable dielectric layer free from defects such as pinholes and cracks. A fifth object of the present invention is to provide a method of manufacturing a PDP having a dielectric layer having excellent surface smoothness.

In the method for producing a PDP of the present invention, a film-forming material layer is formed by applying a paste-like composition containing glass powder, an acrylate-based resin and a solvent on a support film, and the film formed on the support film Forming a dielectric layer on the surface of the glass substrate by transferring the forming material layer to the surface of the glass substrate to which the electrodes are fixed, and baking the transferred film forming material layer. I do.

The transfer film for forming a dielectric layer of the plasma display panel of the present invention,
A transfer film used to form a dielectric layer in a plasma display panel,
A support film;
On this support film, a glass-forming material, a paste-like composition containing an acrylate resin and a solvent, having a film-forming material layer having a thickness of 10 to 200 μm,
When the film forming material layer is transferred to the surface of a glass substrate and baked to form a dielectric layer, the thickness tolerance of the dielectric layer is within ± 5%.

In the method for producing PDP of the present invention, the following embodiments are preferable.
(1) The thickness of the film forming material layer is 10 to 200 μm.
(2) The thickness of the film forming material layer is 30 to 100 μm.
(3) The thickness tolerance of the formed dielectric layer is within ± 5%.
(4) A film-forming material layer is formed by applying a paste-like composition on a support film by a roll coater.
(5) Forming a film-forming material layer by applying a paste-like composition onto a support film by an application means selected from a doctor blade, a curtain coater, and a wire coater. (6) The support film is a flexible resin film.
(7) The support film is a polyethylene terephthalate film.
(8) The surface of the support film has been subjected to a release treatment.
(9) firing the transferred film forming material layer at a temperature of 500 ° C. or lower.
(10) firing the transferred film forming material layer at a temperature of 400 to 500 ° C.
(11) The viscosity of the paste composition is from 500 to 10,000 cp.
(12) The glass powder contained in the film forming material layer is a mixture of 60 to 90% by weight of zinc oxide, 5 to 20% by weight of boron oxide, and 5 to 20% by weight of silicon oxide.
(13) At least one acrylate resin selected from polymethyl methacrylate, polybutyl methacrylate, and a copolymer of methyl methacrylate and methacrylic acid is contained in the paste composition. .

According to the method of the present invention, even a dielectric layer having a large thickness can be efficiently formed by a simple method including a step of transferring a film forming material layer. Improvement can be achieved, and the production efficiency of PDP can be improved.

Further, according to the method of the present invention, a dielectric layer having a large film thickness can be formed while maintaining the film thickness uniformity (within a film thickness tolerance of ± 5%), which is required for a large panel. Even a dielectric layer can be formed efficiently.

According to the method of the present invention, it is possible to form a dielectric layer excellent in uniformity of film thickness and surface smoothness and free from defects such as pinholes and cracks. Therefore, stable dielectric properties are exhibited by such a highly reliable dielectric layer, and as a result, display defects such as uneven brightness do not occur in the PDP manufactured by the method of the present invention.

In the manufacturing method of the present invention, the film-forming material layer that becomes the dielectric layer by firing may be formed by directly applying a paste composition containing glass powder on a rigid glass substrate. Instead, it is formed by coating on a flexible support film. For this reason, as a method for applying the paste-like composition, an application method using a roll coater or the like can be adopted, whereby a film-forming material layer having a large film thickness and excellent uniformity in film thickness ( For example, 100 μm ± 5 μm) can be formed on the support film. The film forming material layer thus formed can be reliably formed on the glass substrate by a simple operation of collectively transferring the film forming material layer to the surface of the glass substrate. Therefore, according to the manufacturing method of the present invention, it is possible to improve the process (higher efficiency) in the process of forming the dielectric layer and to improve the quality of the formed dielectric layer (exhibit stable dielectric characteristics). Can be planned.

Hereinafter, the production method of the present invention will be described in detail. In the manufacturing method of the present invention, the dielectric layer is formed on the surface of the glass substrate by the step of transferring the film forming material layer by using the transfer film and the step of baking the film forming material layer.
(1) Transfer film:
The transfer film used in the production method of the present invention includes a support film and a film-forming material layer formed on the support film.

支持 The support film constituting the transfer film is preferably a resin film having heat resistance and solvent resistance and having flexibility. When the support film has flexibility, the paste composition can be applied by a roll coater, and the film forming material layer can be stored and supplied in a rolled state. Examples of the resin forming the support film include fluorine-containing resins such as polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyimide, polyvinyl alcohol, polyvinyl chloride, and polyfluoroethylene, nylon, and cellulose. The thickness of the support film is, for example, 20 to 100 μm.

The film forming material layer constituting the transfer film is a glass powder, a paste composition containing an acrylate resin as a binder resin and a solvent as essential components is applied on the support film, and the coating film is dried. By removing a part or all of the solvent.

Examples of the glass powder which is an essential component of the paste composition include: 1) a mixture of zinc oxide, boron oxide, and silicon oxide (ZnO—B ₂ O ₃ —SiO ₂ ); 2) lead oxide, boron oxide, and oxide. mixtures of silicon _{(PbO-B 2 O 3 -SiO} 2 system), 3) lead oxide, boron oxide, silicon oxide, a mixture of aluminum oxide _{(PbO-B 2 O 3 -SiO} 2 -Al 2 O 3 system), 4 ) lead oxide, zinc oxide, boron oxide, and the like mixture of silicon oxide _{(PbO-ZnO-B 2 O} 3 -SiO 2 system). Among these, a paste-like composition comprising a mixture of ZnO-B ₂ O ₃ -SiO ₂ system whose main component is zinc oxide, it can be baked at a relatively low temperature conditions (500 ° C. or less) It is preferred in that respect.

The acrylate ester resin, which is an essential component of the paste composition, has an appropriate tackiness and can bind glass powder, and is completely formed by baking (400 to 500 ° C.) the film forming material layer. Examples thereof include polymethyl methacrylate, polybutyl methacrylate, and a copolymer of methyl methacrylate and methacrylic acid.

As a solvent which is an essential component of the paste composition, the paste composition can be given an appropriate viscosity (for example, 500 to 10,000 cp), and can be easily evaporated and removed from the paste composition by a drying treatment. Preferably, turpentine, cellosolve (ethyl cellosolve), methyl cellosolve, terpineol, butyl carbitol acetate, butyl carbitol, benzyl alcohol, methyl lactate, ethyl lactate and the like can be suitably used.

The paste composition contains, in addition to the above essential components, various additives such as a dispersant, a tackifier, a plasticizer, a surface tension regulator, a stabilizer, and an antifoaming agent as optional components. Is also good.

As an example of a preferable paste-like composition, as a glass powder, 100 parts by weight of a mixture composed of 60 to 90% by weight of zinc oxide, 5 to 20% by weight of boron oxide and 5 to 20% by weight of silicon oxide, and polymethyl methacrylate Or a composition containing, as essential components, 2 to 10 parts by weight of a copolymer (acrylate resin) of methyl methacrylate and methacrylic acid and 10 to 50 parts by weight of terpineol (solvent). .

As a method for applying the paste-like composition on a support film, it is necessary that a paste having a uniform thickness and a large thickness (for example, 30 μm or more) can be efficiently formed. Specifically, a coating method using a roll coater, a coating method using a doctor blade, a coating method using a curtain coater, a coating method using a wire coater, and the like can be mentioned as preferable examples.

(4) The surface of the support film to which the paste composition is applied is preferably subjected to a release treatment. This makes it possible to easily perform the peeling operation of the support film in the transfer step described later.

The conditions for drying the coating film are, for example, about 50 to 150 ° C. for about 0.5 to 30 minutes, and the residual ratio of the solvent after drying (content in the film forming material layer) is usually within 10% by weight. Is done.

The thickness of the film-forming material layer formed as described above varies depending on the glass powder content, the type and size of the panel, and the like, but is, for example, 10 to 200 μm, and preferably 30 to 100 μm. . If the thickness is less than 10 μm, the thickness of the finally formed dielectric layer becomes too small, and the desired dielectric properties may not be secured. Usually, when the thickness is 30 to 100 μm, the thickness of the dielectric layer required for a large panel can be sufficiently ensured.

The transfer film may be provided with a protective film layer on the surface of the film forming material layer. Examples of such a protective film layer include a polyethylene film and a polyvinyl alcohol-based film.
(2) Step of transferring the film forming material layer:
The production method of the present invention is characterized in that the transfer film prepared as described above is used, and the film forming material layer constituting the transfer film is transferred to the surface of the glass substrate to which the electrodes are fixed. is there.

An example of the transfer step is as follows. After peeling off the protective film layer of the transfer film used as necessary, the transfer film is superimposed on the surface of the glass substrate (electrode fixing surface) so that the surface of the film forming material layer is brought into contact with the transfer film. After thermocompression bonding of the film with a heating roller or the like, the support film is peeled off from the film forming material layer. Thereby, the film-forming material layer is transferred to the surface of the glass substrate and brought into close contact therewith. Here, as the transfer conditions, for example, the surface temperature of the heating roller is 80 to 100 ° C., the roll pressure by the heating roller is 1 to 5 kg / cm ² , and the moving speed of the heating roller is 0.5 to 10.0 m / min. Can be shown. The glass substrate may be preheated, and the preheating temperature may be, for example, 40 to 60 ° C.
(3) Firing step of the film forming material layer:
The film forming material layer transferred to the surface of the glass substrate is fired. Specifically, by placing the glass substrate on which the film-forming material layer is formed in a high-temperature atmosphere, the organic substances (eg, binder resin, residual solvent, ) Is removed by decomposition or the like, and the glass powder as an inorganic substance is melted and sintered. Thus, a dielectric layer made of a glass sintered body is formed on the glass substrate. Here, the firing temperature varies depending on the constituents in the film forming material layer, but is, for example, 400 to 500 ° C.

[Example]
Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto. In the following, “parts” indicates “parts by weight”.

<Example>
[Transfer film manufacturing process]
As the glass powder, zinc oxide 80 wt%, boron oxide 10 wt%, and 100 parts of a mixture of _ZnO-B 2 O 3 -SiO ₂ system with a composition of the silicon oxide 10 wt%, and methacrylic acid (10 wt%) of methacrylic 30 parts of a copolymer (weight average molecular weight: 100,000) (methyl acrylate resin) with methyl acrylate (90% by weight), 30 parts of ethylene glycol diacrylate (tackifier), and methyl cellosolve (solvent) ) And kneaded with 60 parts to prepare a paste composition having a viscosity of 5,000 cp.

Next, the prepared paste-like composition is applied to a support film (width 200 mm, length 30 m, thickness 38 μm) made of a polyethylene terephthalate (PET) film which has been previously subjected to a mold release treatment using a roll coater. Was formed. The formed coating film was dried at 110 ° C. for 2 minutes to completely remove the solvent, thereby producing a transfer film having a 50 μm-thick film-forming material layer formed on a support film.

(Transfer process of film forming material layer)
A transfer film was superimposed on the surface of the glass substrate for a 6-inch panel (the fixed surface of the bus electrode) so that the surface of the film-forming material layer was in contact with the surface, and the transfer film was thermocompression-bonded with a heating roller. Here, as pressure bonding conditions, the surface temperature of the heating roller was 120 ° C., the roll pressure was 4 kg / cm ² , and the moving speed of the heating roller was 1 m / min. After the completion of the thermocompression bonding, the support film was peeled off from the film forming material layer. As a result, the film-forming material layer was transferred to the surface of the glass substrate and brought into close contact therewith. When the film thickness of this film forming material layer was measured, it was in the range of 50 μm ± 2 μm.

(Firing step of film forming material layer)
The transferred film-forming material layer is heated from room temperature to 450 ° C. at a rate of 10 ° C./min, and is baked for 30 minutes in a 450 ° C. temperature atmosphere, so that the surface of the glass substrate is sintered with glass. A dielectric layer consisting of a body was formed. When the film thickness of this dielectric layer was measured, it was in the range of 35 μm ± 1.5 μm, and the film had excellent uniformity in film thickness.

(Performance evaluation of dielectric layer)
In this way, five panel materials made of a glass substrate having a dielectric layer were produced. When the cross section and the surface of the formed dielectric layer were observed with a scanning electron microscope, no film defects such as pinholes and cracks were found in the dielectric layers formed on all panel materials.

<Comparative example>
A paste-like composition having the same composition as in the example is prepared, and a glass paste is applied on a glass substrate (a substrate similar to that used in the example) by multiple printing using a screen printing method to form a film. A material layer was formed. Here, the dry film thickness by one application was about 15 to 17 μm, and the number of applications was three. When the film thickness of the obtained film forming material layer was measured, it was in the range of 50 μm ± 5 μm. Next, a baking treatment was performed in the same manner as in the example to form a dielectric layer on the surface of the glass substrate. When the film thickness of this dielectric layer was measured, it was in the range of 35 μm ± 4 μm, and the uniformity of the film thickness was poor. In this way, five panel materials made of a glass substrate having a dielectric layer were produced. When the cross section and the surface of the formed dielectric layer were observed with a scanning electron microscope, film defects such as pinholes and cracks were recognized in 60% (for three panels) of the panel material.

It is a schematic diagram which shows the cross-sectional shape of an AC type plasma display panel.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Glass substrate 3 Partition wall 4 Bus electrode 5 Address electrode 6 Phosphor 7 Dielectric layer 8 Protective layer

Claims (1)

A transfer film used to form a dielectric layer in a plasma display panel,
A support film;
On this support film, a glass-forming material, a paste-like composition containing an acrylate resin and a solvent, having a film-forming material layer having a thickness of 10 to 200 μm,
When the film forming material layer is transferred to the surface of a glass substrate and fired to form a dielectric layer, the thickness tolerance of the dielectric layer is within ± 5%. Transfer film for body layer formation.

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