WO2006004260A1

WO2006004260A1 - Method of manufacturing reflection layer on pdp rear plate via osmotic pressure coating using greeen sheet

Info

Publication number: WO2006004260A1
Application number: PCT/KR2005/000866
Authority: WO
Inventors: Yong Seog Kim; Doyoung Park; Yu Jeong Cho
Original assignee: Yong Seog Kim; Doyoung Park; Yu Jeong Cho
Priority date: 2004-03-26
Filing date: 2005-03-25
Publication date: 2006-01-12
Also published as: KR20050095379A; KR100569173B1

Abstract

The present invention relates to a process for forminga reflective film on a plasma dislay panel (PDP) rear plate utilizing a transfer sheet, comprising coating the transfer sheet on an inner wall of a discharge cell, taking advantage of osmotic pressure and swelling occuring when the transfer sheet contacts the organic coating solvent, and calcining organic materials present in the transfer sheet to form a reflective film. In accordance with present invention, it is possible to form the reflective film on inner walls of discharge cells having fine and complex shapes such as waffle, honeycomb, meander, fishbone and SDR type closed cells and thereby it is possible to improve luminous efficiency of the PDP, and to reduce production coast of the rear plate due to the simplified manufacturing process.

Description

METHOD OF MANUFACTURING REFLECTION LAYER ON PDP REAR PLATE VIA OSMOTIC PRESSURE COATING USING

GREEN SHEET

FIELD OF THE INVENTION

The present invention relates to a process for forming a reflective film on a rear plate of a plasma display panel (PDP), involving coating and baking a transfer sheet on Barrier Ribs of the PDP via an osmotic pressure method. More particularly, the present invention relates to a process for forming a reflective film, comprising filling a solvent having superior permeability through a transfer sheet (hereinafter, referred to as "coating solvent") on a rear plate having barrier ribs formed thereon, attaching the transfer sheet to the coating solvent, such that osmotic pressure is exerted when the coating solvent evaporates while permeating through the transfer sheet, and at the same time, the transfer sheet is swelled by the coating solvent, thereby coating the transfer sheet on the barrier rib and rear dielectric surfaces, and calcining the coated transfer sheet to form a reflective film.

BACKGROUND OF THE INVENTION

Plasma display panels (PDPs) are a form of flat panel display and have advantages such as high image quality, thinness and light-weight and thus are primarily used in large-sized displays having a size of greater than 40 inches. The PDP displays images or pictures by formation of pixels at crossings at which barrier ribs and address electrodes formed on a rear plate, and sustain electrodes formed on a front plate, vertically cross each other.

The schematic structure of the PDP is shown in FIG. 1. A dielectric layer 90 is coated on a rear plate 80 made up of a glass or metal substrate, and address electrodes 50 are formed on the rear plate 80 or dielectric layer 90. Thick and long stripe-like barrier ribs 60 are present between the address electrodes 50 and phosphors are applied to surfaces defined in spaces between barrier ribs 60, thereby constituting sub-pixels. Sustain electrodes 40 are formed within a front plate 10 made of glass and a dielectric 20 and an MgO protective layer 30 are formed below sustain electrodes 40. Therefore, upon combining the front plate 10 with the rear plate 80, plural pixel spaces isolated by barrier ribs 60 are formed. He/Xe gas or Ne/Xe gas is enclosed in the isolated spaces and thus application of voltage to sustain electrodes 40 and address electrodes 50 leads to formation of plasma within the spaces. Then, vacuum UV light generated from plasma excites phosphors coated on side surfaces of barrier ribs and bottom surfaces between barrier ribs, thereby generating red, green, and blue visible light.

Since the luminous efficiency of the PDP greatly affects power consumption, a great deal of research and study to enhance luminous efficiency are actively underway. The luminous efficiency of the PDP is primarily affected by vacuum UV-generation efficiency, phosphor efficiency, and visible light- use efficiency. As the vacuum UV- generation efficiency is largely affected by electric discharge voltage, components of discharge gas, and pressure, use of discharge gas containing a high fraction of Xe having superior discharge efficiency is gradually increasing. Phosphor efficiency refers to the efficiency with which vacuum UV-exposed phosphors emit visible light (transition rate of UV to visible), and development of phosphors having a high- luminosity structure and composition is underway. Some portion of visible light generated from phosphors is scattered and absorbed in discharge cells, or is transmitted through the rear plate, thereby being lost. The other portion of the visible light transmits through the front dielectric and then is used to display images or pictures. In order to prevent loss of visible light that is transmitted to the back of the rear plate, there has been used a rear dielectric layer containing high-reflectivity ceramic fillers such as TiO₂ and ZnO. However, such ceramic fillers exhibit a limit to increase a volume fraction in the rear dielectric layer. Upon increasing the content of the ceramic filler, the sintered density at a given temperature decreases, thus making it difficult to exert sufficient role as the rear dielectric layer. Therefore, glass-ceramic composite materials having a volume fraction of the ceramic filler in the range of 10 to 30 vol% are primarily employed as the rear dielectric layer. Due to such low ceramic filler fraction, a considerable amount of visible light is lost by transmission through the rear dielectric layer to the rear glass substrate.

In order to solve such problems, Korean Patent Publication Laid-open No.

1998-015351 discloses a method involving application of a reflective film having a thickness of 500 to 5000 A to the PDP rear substrate, in the form of a metal film or oxide film on the rear plate. Korean Patent Publication Laid-open No. 2000-61882 proposes a method of increasing reflectivity by optionally forming a reflective film below address electrodes of the rear substrate. Korean Patent Publication Laid-open No. 2000-7457 discloses a method of forming a reflective film on the front side of the rear substrate, on phosphors, and lower parts of barrier ribs. In addition, Korean Patent Publication Laid-open No. 2000-65280 proposes a method of improving PDP efficiency by forming a mirrored surface on the rear plate. Meanwhile, Phillips has published results obtained by application of a TiO₂ layer as a reflective film (SID'03 digest, pp 848-851). This technique discloses a structure having a TiO₂ layer formed on the inner walls of the discharge cells. Such a structure reflects visible light, generated from the discharge cells, not only at barrier ribs, but also at the bottom surfaces of the discharge cells, thereby increasing reflection efficiency. This technique reportedly provides a 50% increase in discharge efficiency. In addition, this technique is also expected to improve the contrast ratio of the PDP, as visible light does not pass through adjacent discharge cells.

In order to sufficiently fulfill the role of TiO₂ layer as the reflective film, the TiO₂ layer should be uniformly formed in the discharge cells. A representative method of forming the reflective film is printing. This method involves printing a paste containing TiO₂ powder on the upper parts of barrier ribs using a patterned printing screen, and flow coating the paste upon surfaces of barrier ribs and rear plate dielectric layers via viscosity of the printed paste. According to this method, a thin reflective film is formed upon the upper surfaces of the barrier ribs, whereas reflective material accumulates at the lower corner sides. Therefore, when it is desired to maintain the necessary thickness of reflective film inside the discharge cell, excessive formation of reflective film on corner sides leads to increased loss of material and reduced discharge space. In addition, with the development of large PDPs having a size greater than 50 inches, formation of phosphor films on such panels via the printing process is beginning to become economically infeasible. That is, as the size of the PDP increases, the life span of the printing screen decreases and alignment between the discharge cell and printing screen becomes difficult, resulting in problems associated with reduced production yield and productivity of PDP rear plates (PRP). Further, as recent PDPs require high resolution and high efficiency, various closed discharge cells, on which the reflective film will be formed, such as waffle, honeycomb, meander, fishbone and SDR discharge cells have been proposed as replacements for the conventional striped discharge cells. However, such discharge cells suffer from a greater difficulty in alignment between discharge cell and printing screen and difficulty to obtain the uniform reflective film, thereby reducing production yield and productivity of the PDP rear plate.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made to solve the above and other technical problems that have yet to be resolved, and it is an object of the present invention to provide a novel osmotic pressure coating method for forming a reflective film composed of ceramic powder and inorganic binder powder. Specifically, objects of the present invention are as follows.

Firstly, the object of the present invention is to provide a technique capable of preparing a reflective film on striped simple barrier ribs having a thin barrier rib width of 10 to 50 μm, as well as on inner walls of closed discharge cells such as meander, waffle, honeycomb and SDR types, by replacing a method of forming a reflective film via printing with the osmotic pressure coating method.

Secondly, the object of the present invention is to provide a technique for forming a reflective film, capable of raising discharge efficiency of a PDP by providing a uniform reflective film formation process to maximize discharge spaces in discharge cells. Thirdly, the object of the present invention is to provide a technique capable of reducing PDP manufacturing process costs by substitution of a printing process having low productivity and yield in a reflective film manufacturing process with a transfer sheet forming process having high uniformity and productivity.

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a process for forming a reflective film for a plasma display panel (PDP), comprising preparing a transfer sheet containing ceramic powder and inorganic binder powder for a reflective film, applying a coating solvent capable of generating osmotic pressure to a rear plate having barrier ribs formed thereon to a predetermined thickness, attaching the transfer sheet to the applied coating solvent, allowing the transfer sheet to be compressed on surfaces of the barrier ribs and rear dielectric by generation of swelling and osmotic pressure in the course of permeation of the coating solvent through the transfer sheet, and calcining.

In accordance with a feature of the present invention, there is provided the great reduction in non-uniformity of the reflective film that may be caused by heterogeneous external pressure and heat, and elimination of air trapping in closed cells, by forming the transfer sheet to conform to the inner wall surfaces of the PDP discharge cells via osmotic pressure, thereby forming a reflective film. Thus, it is possible to easily prepare the reflective film having a desired shape.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In order to carry out formation of the reflective film using osmotic pressure in accordance with the present invention, the following three requirements should be satisfied: (1) permeability of the coating solvent through the transfer sheet, which will be applied to the rear plate having barrier ribs formed thereon, should be high enough to obtain desired productivity, (2) the transfer sheet should be suitably swelled by the coating solvent, thereby exhibiting superior coating quality, and (3) the transfer sheet should have suitable adhesion to upper surfaces of the barrier rib and rear dielectric after evaporation of the coating solvent.

The first requirement, i.e., the permeability of the coating solvent to the transfer sheet is preferably in the range of 10^"3 to 10^"6 cm³/cm²-sec, and more preferably 10^"4 to 10^"5 cm³/cm²-sec, in order to achieve desired productivity of a suitable osmotic pressure-fluorescent film formation process. For example, if a coating solvent having a permeability of 10^"4 cm³/cm²-sec is filled in the rear substrate having a barrier rib height of 120 μm, coating solvent permeates the transfer sheet and then evaporates, and as a result, it takes about 120 seconds to form the fluorescent film. Therefore, considering stability and productivity of the coating process, selection of a suitable coating solvent and the organic composition of the transfer sheet may be necessary to ensure suitable permeability of the coating solvent.

The second requirement, suitable swellability, is dictated by the shape of the discharge cells. For example, in order to ensure that the transfer sheet placed on the upper part of 40-inch PDP stripe-type discharge cell is deformed and uniformly coated on the barrier rib surface and rear dielectric upper surface, the transfer sheet should be able to be elongated to about 100% (assumed that, barrier rib pitch: 270 μm, barrier rib height: 130 μm, and barrier rib width: 60 μm). The desired elongation (%) of the transfer sheet may be obtained by the following two methods. The first method takes advantage of the swelling phenomenon of the transfer sheet occurring when the transfer sheet contacts the coating solvent. That is, the required elongation is obtained through swelling of the transfer sheet by the coating solvent. The second method is to design physical properties of the transfer sheet so as to have suitable elongation at break and strength as the transfer sheet is elongated by osmotic pressure upon coating. When swelling is used to obtain the required elongation, the resulting coating layer suffers from severe creasing. In comparison, when the required elongation is obtained by osmotic pressure, there is, disadvantageous^, variation between upper and lower thickness of the coating, and partial separation of coating in corners at which barrier ribs meet with the rear dielectric layer. Therefore, in the case of striped discharge cells, the swellability of the transfer sheet relative to the selected coating solvent is preferably greater than 50% of the required elongation. Whereas, in the case of closed cells such as a waffle structure, since deformation occurs under plane strain conditions, such discharge cells exhibit higher swellability as compared to striped discharge cells in which uniaxial elongation occurs. Therefore, it is necessary to control the swellability of the transfer sheet depending upon the discharge cell structure.

The third requirement pertains to adhesion of the transfer sheet. When the coating solvent completely volatilizes from the discharge cells and transfer sheet, the transfer sheet shrinks. As such, the coated transfer sheet is subjected to strain causing it to be delaminated from surfaces of barrier ribs and rear dielectric. Therefore, it is necessary to design the composition of the transfer sheet so that the adhesion of the transfer sheet can withstand such detaching force.

The transfer sheet capable of satisfying the above-mentioned requirements comprises ceramic powder for the reflective film, inorganic binder powder, an organic binder, a plasticizer, a dispersant, and other organic additives.

As the ceramic powder for the reflective film, titanium dioxide (TiO₂), zinc oxide (ZnO), alumina (Al₂O₃), silica (SiO₂), magnesium oxide (MgO), barium titanate

(BaTiO₃), strontium titanate (SrTiO₃), hexagonal boron nitride (hBN), aluminum nitride (AlN), diamond or the like may be used. These materials may be used alone or in any combination thereof.

The inorganic binder powder is a low-melting point ceramic powder that is added to promote binding between the above-mentioned powders after calcining the reflective film. For example, low-melting point solder glass powder, low-melting point glass powder, and, if necessary, a mixture thereof may be used as the inorganic binder powder.

As the organic binder, a thermoplastic resin may be primarily employed. For example, mention may be made of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, isobutyl acrylate, isobutyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, hydroxy ethyl acrylate, hydroxy ethyl methacrylate, ethyl cellulose, cellulose derivatives, polyvinyl butyral (PVB), polyacrylate esters or any combination thereof.

The plasticizer affects glass transition temperature of the transfer sheet and adhesion to barrier ribs. As representative examples, mention may be made of diethyl oxalate, polyethylene, polyethylene glycol (PEG), dimethyl phthalate (DMP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), methyl abietate, butyl benzyl phthalate or any combination thereof. The dispersant may vary depending upon the powder to be used. There is no particular limit to the dispersant so long as it can uniformly disperse the ceramic powder for the reflective film in a solvent for use in slurry for preparing the transfer sheet by electrostatic repulsive force or steric repulsive force and mixed repulsive forces thereof.

As the organic additive, a viscosity controlling agent for improving slurry viscosity and manufacturing properties of the transfer sheet, an adhesive agent for improving adhesion of the transfer sheet, or the like, may be added. The viscosity controlling agent may include, for example, hydroxy ethyl cellulose, methyl cellulose, carboxymethyl cellulose, casein, sodium caseinate, polyvinyl alcohol, polyacrylate ester, polymethacrylate ester, aluminum stearate, zinc stearate, aluminum octylate, fatty acid amide or the like. The adhesive agent serves to further increase adhesion after drying the sheet. For example, rubber, acrylate, silicon or vinyl adhesive may be employed. As the rubber adhesive, mention may be made of natural rubbers and synthetic rubbers such as SBR, SBS, and SIS, and tackifiers, such as rosin and derivatives thereof, terpene resin, and petroleum resin. As the acrylate adhesive, solvent-type polyacrylate and its copolymers, polyacrylic acid, polymethacrylic acid, 2-ethylhexyl acrylate, n-butyl acrylate, 2-ethyl acrylate, n-octyl acrylate, methacrylate or the like may be employed. As the polyvinyl adhesive, polyvinyl acetate, polyvinyl pyrrolidone or the like may be employed. The silicone adhesive may include polydimethyl siloxane or polydimethyldiphenyl siloxane or the like.

Suitable solvents may be utilized in the manufacturing process of the transfer sheet such that the slurry composed of the above-mentioned components can be easily formed into a sheet. As such solvents, solvents that have been used in conventional green tapes may be employed.

The inorganic binder powder is added in an amount of 1 to 20 parts by weight, and preferably 5 to 10 parts by weight, based on 100 parts by weight of the ceramic power for the reflective film. The organic binder is added in an amount of 2 to 20 parts by weight, and preferably 8 to 12 parts by weight, based on 100 parts by weight of the mixed powder. The plasticizer is added in an amount of 0 to 12 parts by weight, and preferably 4 to 6 parts by weight, based on 100 parts by weight of the mixed power. 0 to 12 parts by weight, and preferably 8 to 12 parts by weight, based on 100 parts by weight of the mixed power, of adhesive agent is added. Contents of theses additives may vary depending upon the particle size of the mixed powder. The finer the particle size the greater the added amount.

An example of the preferred process of the present invention is shown in FIG. 2. Specifically, this process is carried out by the following steps:

(1) preparing the transfer sheet having permeability of the selected organic coating solvent in the range of 10^"3 to 10^'6 cm³/cm²-sec, suitable swellability by the organic coating solvent and adhesion to barrier ribs greater than detaching force therefrom, upon coating;

(2) uniformly applying the organic coating solvent to a rear substrate having calcined barrier ribs formed thereon;

(3) attaching the transfer sheet prepared in step (1) to the rear substrate;

(4) forming a reflective film in such a manner that the coating solvent permeates through the transfer sheet, and due to swelling and osmotic pressure generated in this process, the transfer sheet is coated on surfaces of barrier ribs and rear dielectric, thereby forming the reflective film; and

(5) heating the thus-formed reflective film to a calcination temperature to burn-out organic materials contained in the transfer sheet, thereby obtaining a finished reflective film.

The manufacturing process as defined in the present specification falls within the range generally acceptable in the art, regarding reflective film forming processes. Therefore, unless otherwise particularly specified, set conditions such as the thickness of the transfer sheet, temperature, time or the like in such a process are defined as the ranges that are acceptable for optimal performance.

The thickness of the transfer sheet in step (1) is not particularly limited so long as the desired thickness of the reflective film after calcination can be obtained. The thickness of the transfer sheet is preferably in the range of 10 μm to 50 μm, and more preferably 20 μm to 30 μm. The transfer sheet may be prepared using various methods such as doctor blade coating, comma coating, roll coating, nip coating and die coating well known in the art.

Application of the coating solvent in step (2) may be performed via a variety of methods. As representative methods, mention may be made of dispensing, dipping, spin coating, and the like. The coating solvents are conventional organic coating solvents including water, and are not particularly limited so long as they satisfy the requirements as discussed above. The coating solvent is added in an amount sufficient to fill the cell. As the coating solvent that can be utilized in the present invention, mention may be made of water, ethanol, methanol, propanol, isobutyl alcohol, n- propyl alcohol, tetrahydrofuran, n-propyl acetate, n-butyl acetate, 2-ethylhexyl acetate, ethyl acetate, methyl acetate, cyclohexanol, cyclohexanone, pyridine, diisobutyl carbitol, acetone, methylethyl ketone, diethyl ketone, methylisobutyl ketone, toluene, xylene, benzene or any combination thereof, for example.

In step (3), attaching of the transfer sheet to the rear plate is not particularly limited. For example, there is a method involving positioning the transfer sheet on the rear substrate and removing a carrier film of the transfer sheet, a lamination method, or the like. In this connection, in order to prevent air from being trapped between the transfer sheet and coating solvent (applied coating solvent), preferably the transfer sheet is sequentially attached from one direction of the rear substrate to the other direction.

In step (4), in order to improve stability and productivity of the process in formation of the reflective film taking advantage of osmotic pressure, the rear substrate may be heated or air blasting may be applied enough to generate atmospheric flow on the surface of the transfer sheet. Heating the rear substrate provides effects of increased permeability of the coating solvent to the transfer sheet. Activation of atmospheric flow on the surface of the transfer sheet improves permeability by lowering the partial pressure of the coating solvent on the sheet surface. The heating temperature of the rear substrate is preferably in the range of 30 to 100⁰C. Air blast pressure to cause atmospheric flow is preferably in the range of 1 to 5 atm.

After complete evaporation of the coating solvent from the transfer sheet and PDP rear substrate, the rear substrate is heated to the calcination temperature to decompose and remove organic materials present in the transfer sheet. The calcination temperature is a temperature at which organic materials present in the transfer sheet can be decomposed and oxidized to be effectively removed therefrom. The calcination temperature is preferably in the range of 400 to 52O⁰C. On the other hand, in order to increase reflection efficiency of the reflective film in the discharge cell, the reflective film may be applied as the layer composed of two or more reflective powder layers.

In accordance with another aspect of the present invention, there is provided a plasma display panel (PDP) manufactured utilizing the rear plate having the above- mentioned barrier ribs formed thereon. Methods of manufacturing the PDP utilizing the barrier rib-formed rear plate are well known in the art and therefore details thereof are omitted.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 schematically shows a cross-sectional perspective view of a structure of a plasma display panel;

& FIG. 2 schematically shows a process flow chart for forming a reflective film in accordance with one embodiment of the present invention; and

FIGS. 3 through 5 are SEMs of reflective films on various barrier rib forms prepared according to embodiments of the present invention.

EXAMPLE

1 part by weight of a dispersant BYK-111 (available from BYK Chemie, Germany) and ZnSi₂O₄:Mn²⁺ powder having an average particle diameter of 1.0 mm were added to a mixed solvent of methylethylketone and toluene, and the resulting mixture was stirred for 8 hours using a ball mill. Next, 8 parts by weight of ethyl cellulose having a weight average molecular weight of 90,000 and 12 parts by weight of polyacrylate adhesive having a weight average molecular weight of 90,000 were added thereto and the mixture was additionally milled for 12 hours to obtain a slurry. The thus-obtained slurry was formed into a transfer sheet having a thickness of 30 μm using a doctor blade (organic content : 55% by weight). The transfer sheet was coated on stripe-, honeycomb- and waffle-type barrier ribs, respectively, using solvents such as ethyl alcohol, isopropyl alcohol, and n-butyl acetate as coating solvents, and calcined at a rate of 5°C/min and temperature of 580⁰C, thereby forming reflective films.

FIGS. 3 through 5 are SEMs of the thus-formed various reflective films. As can be seen, in accordance with the method of the present invention, reflective films were uniformly formed on surfaces of the barrier ribs and rear dielectric.

INDUSTRIAL APPLICABILITY

As described above, in accordance with the method of manufacturing a reflective film formed on the PDP rear plate (PRP) of the present invention, since the transfer sheet for the reflective film is formed on surfaces of barrier ribs and rear dielectric taking advantage of using osmotic pressure of a coating solvent, it is possible to prevent problems and disadvantages that had been exhibited by conventional printing process, such as alignment errors occurring upon large-area printing, short life span of a printing screen and increased production costs due to complicated processes, decreased discharge space due to variation in the thickness of the reflective film leading to decreased PDP discharge efficiency, and mechanical damage to barrier ribs by the printing screen. In addition, considering the demand for high resolution PDPs, which in turn leads to reduced thickness of barrier ribs, and employment of discharge cells having closed-cell structures, it is also possible to form a reflective film having a uniform thickness in high-resolution, closed discharge cells, thereby providing a method capable of producing a high-definition PDP. Consequently, the method in accordance with the present invention can improve luminosity of the PDP rear plate, yield of products and uniformity of quality. In addition, such a formation method of the reflective film can significantly reduce production costs of the PDP rear plate.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

WHAT IS CLAIMED IS;

1. A process for forming a discharge cell reflective film for a plasma display panel (PDP), comprising preparing a transfer sheet containing ceramic powder and inorganic binder powder for a reflective film, applying a coating solvent capable of generating osmotic pressure to a rear plate having barrier ribs formed thereon to a predetermined thickness, attaching the transfer sheet to the applied coating solvent, allowing the transfer sheet to be compressed on surfaces of the barrier ribs and rear dielectric by generation of swelling and osmotic pressure in the course of permeation of the coating solvent through the transfer sheet, and calcining.

2. The process according to claim 1, wherein combination of the transfer sheet and coating solvent simultaneously satisfies the following requirements:

(1) High permeability of the coating solvent through the transfer sheet applied to the rear plate having barrier ribs formed thereon, sufficient to achieve suitable productivity;

(2) Suitable swellability of the transfer sheet by the coating solvent, thereby exhibiting superior coating quality; and

(3) Suitable adhesion of the transfer sheet so as to be adhered to the upper surfaces of the barrier rib and rear dielectric after evaporation of the coating solvent.

3. The process according to claim 2, wherein the permeability of the coating solvent to the transfer sheet is in the range of 10^'3 to 10^'6 cm³/cm² sec; for a striped discharge cell, the swellability of the transfer sheet to the selected coating solvent is greater than 50% of the required elongation, and for discharge cells other than the striped cell, the swellability of the transfer sheet is higher than the above-mentioned range; and the transfer sheet dried after coating has adhesion to barrier ribs greater than detaching force therefrom.

4. The process according to claim 1, wherein the transfer sheet is comprised of ceramic powder for the reflective film; 1 to 20 parts by weight of inorganic binder powder, based on 100 parts by weight of the ceramic power for the reflective film; 2 to 20 parts by weight of organic binder, based on 100 parts by weight of the mixed power; 0 to 12 parts by weight of a plasticizer, based on 100 parts by weight of the mixed powder; and 0 to 12 parts by weight of the adhesive, based on 100 parts by weight of the mixed powder.

5. The process according to claim 4, wherein

(a) the ceramic powder for the reflective film is selected from the group consisting of titanium dioxide (TiO₂), zinc oxide (ZnO), alumina (Al₂Os), silica (SiO₂), magnesium oxide (MgO), barium titanate (BaTiO₃), strontium titanate (SrTiO₃), hexagonal boron nitride (hBN), aluminum nitride (AlN), diamond and any combination thereof;

(b) the inorganic binder powder is a low-melting point ceramic powder, and is selected from the group consisting of low-melting point solder glass powder, low- melting point glass powder and any combination thereof;

(c) the organic binder is selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n- propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, isobutyl acrylate, isobutyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-hexyl acrylate, n- hexyl methacrylate, hydroxy ethyl acrylate, hydroxy ethyl methacrylate, ethyl cellulose, cellulose derivatives, polyvinyl butyral (PVB), polyacrylate esters and any combination thereof;

(d) the plasticizer is selected from the group consisting of diethyl oxalate, polyethylene, polyethylene glycol (PEG), dimethyl phthalate (DMP), dibutyl phthalate

(DBP), dioctyl phthalate (DOP), methyl abietate, butyl benzyl phthalate and any combination thereof;

(e) the dispersant is a compound or mixture that uniformly disperses ceramic powder for the reflective film in a solvent for use in slurry for preparing the transfer sheet by electrostatic repulsive force or steric repulsive force and mixed repulsive forces thereof; and

(f) the organic additive is a viscosity controlling agent for improving slurry viscosity and manufacturing properties of the transfer sheet, and/or an adhesive agent for improving adhesion of the transfer sheet.

6. The process according to claim 5, wherein the viscosity controlling agent is selected from hydroxy ethyl cellulose, methyl cellulose, carboxymethyl cellulose, casein, sodium caseinate, polyvinyl alcohol, polyacrylate ester, polymethacrylate ester, aluminum stearate, zinc stearate, aluminum octylate and fatty acid amide; and the adhesive agent is a rubber, acrylate, silicon or vinyl adhesive that further increases adhesion after drying the sheet.

7. The process according to claim 1, wherein the coating solvent is selected from the group consisting of water, ethanol, methanol, propanol, isobutyl alcohol, n- propyl alcohol, tetrahydrofuran, n-propyl acetate, n-butyl acetate, 2-ethylhexyl acetate, ethyl acetate, methyl acetate, cyclohexanol, cyclohexanone, pyridine, diisobutyl carbitol, acetone, methylethyl ketone, diethyl ketone, methylisobutyl ketone, toluene, xylene, benzene or any combination thereof.

8. The process according to claim 1, wherein the transfer sheet is a transfer sheet consisting of two or more reflective powder layers.