KR20010018259A - Photosensitive barrier rib paste composition for plasma display panel and its method of use - Google Patents

Abstract

PURPOSE: A photosensitive paste composition and a forming method of isolation wall are provided to simplify the forming process of isolation walls more than a screen printing method and a sandblast method and to form isolation walls of a PDP(plasma display panel) having high brightness and low power consumption. CONSTITUTION: A photosensitive paste composition includes 40-80wt% of bulkhead powder and 5-50wt% of liquid vehicle. The liquid vehicle consists of 3-15wt% of binder polymer used as a cellulose inducer, 20-60wt% of solvent, 5-40wt% of multi-functional monomer or oligomer, 1-10wt% of photoinitiator and 1-5wt% of additive. The photosensitive paste composition is formed as an isolation wall through photolithography. The photosensitive paste is coated on a glass substrate through a coating machine and then dried. Plural photomasks are arranged and ultraviolet rays are radiated. The paste is dissolved by a developer through difference in solubility between the exposed portion and the non-exposed portion of the exposed substrate. Therefore, plural isolation walls are obtained.

Description

Photosensitive barrier rib paste composition for plasma display panel and its method of use

The present invention relates to a photosensitive partition wall paste composition suitable for forming a partition of a plasma display panel using a photolithography method and a method of forming a partition by a photolithography method using the same.

Plasma display panel (hereinafter referred to as 'PDP') is a vacuum ultraviolet ray (about 147nm wavelength) emitted from the plasma generated when the discharge of inert gas impinges on the fluorescent film to turn red, green, blue light in the visible region. As one of the flat panel display devices using the phenomenon, full color display, fast response speed, wide viewing angle, and easy to implement a large display device of 40 inches or more are possible.

Barrier ribs of the PDP have a height of 80 to 150 which is formed repeatedly on the lower glass substrate every 150 to 300 μm in order to maintain a discharge space and to prevent electrical and optical cross talk between adjacent cells. As the structure of 200㎛, since the discharge efficiency varies depending on the detailed structure of the partition wall, it serves as an important factor to determine the quality of the PDP.

In general, as a method of forming a barrier rib of a PDP, a screen printing method, a sandblast method, a photolithography method, and the like are known. Among these, the method of forming the PDP partition wall by printing method is to use a rubber squeeze to push the printing partition wall paste into an open portion of a screen mask patterned into a predetermined partition wall structure on the glass substrate. After printing to a thickness in the range of 15 to 15㎛, the solvent is removed by drying, and then again repeatedly printed and dried about 8 to 10 times accurately to the printed bulkhead portion to obtain a partition having a height of 80 to 200㎛. Way. This method is not only time-consuming but also difficult to form a barrier rib of uniform height because of repeated printing shifts when forming a barrier rib for a PDP having a large area of 40 inches or more and a high resolution. There is a problem that the yield is low.

In the sand blasting method, a barrier material for printing is entirely coated on a glass substrate with a thickness of 80 to 200 μm, and the desired barrier rib pattern is exposed on the glass substrate using a photosensitive photoresist. The powder (sand) of silicon dioxide, which is a particle, is blown to the exposed portion of the barrier rib pattern to remove the exposed unnecessary portion to form the barrier rib. This method also has a long process time and is not only difficult to form a large-diameter PDP partition wall, but also causes cracks in the partition wall or glass substrate due to physical impact.

As a method for forming a barrier rib of PDP by photolithography, a photosensitive barrier rib paste using an acrylate resin having a carboxyl group (-COOH) as a binder polymer has been proposed in Korean Patent Application No. 97-700891 and US Patent No. 5,909,083. However, in the case of the photosensitive partition wall paste using an acrylate-based resin having a carboxyl group as the binder polymer, the binder polymer and functional properties are caused by the reaction of the carboxylic acid group which is designed to be developed in an aqueous alkali solution among the components of the binder polymer with the partition wall powder showing basicity. Wetness and miscibility between the vehicle and the bulkhead powder composed of monomers, solvents, photoinitiators, and additives, as well as agglomeration of the photosensitive bulkhead paste due to aggregation of the bulkhead powder. There is a problem that the partition wall is partially dropped during the development process of the photolithography process because it is not uniform coating. In addition, by using a photosensitive partition wall paste using an acrylate-based resin as a binder polymer, the cross-linked photosensitive acrylate resin and other organic substances having a function of forming a partition pattern by photolithography and forming a partition wall in a photolithography process are thermally decomposed and removed. Therefore, in the firing process of forming a partition wall made of only inorganic material, the decomposition temperature of about 510 ° C. is required to completely self-crosslink the photosensitive acrylate resin, so that the partition wall forming material is close to the glass transition temperature and the partition wall is uneven. There is a problem that is formed.

The present invention is to solve the problems of the photosensitive partition paste using the printing method, sandblasting method and the conventional acrylate-based resin having a carboxyl group as the binder polymer, and the partition forming method using the same, rather than the printing method and the sandblasting method A photosensitive partition paste composition suitable for forming a partition of a high brightness, low power consumption, high definition plasma display panel having a simple firing process and having a lower firing temperature than a photosensitive partition paste using an acrylate-based resin as a binder polymer and a method of using the same. The purpose is to provide.

1 is a schematic process diagram of forming a partition of a plasma display panel by photolithography using a photosensitive partition paste according to the present invention.

2 is a thermogravimetric analysis of thermal decomposition characteristics of a cellulose derivative, which is a binder polymer of the photosensitive barrier paste used in the present invention, and an acrylate resin, which is a binder polymer of the photosensitive barrier paste used in the related art.

The photosensitive partition wall paste composition of the present invention for achieving the above object comprises a partition powder and a liquid vehicle, the partition powder is composed of 40 to 80% by weight, the vehicle of 5 to 50% by weight, the composition of the liquid vehicle 3-15% by weight of the binder cellulose derivative, 20-60% by weight of solvent, 5-40% by weight of polyfunctional monomer or oligomer, 1-10% by weight of photoinitiator and 1-5% by weight of additive, It is characterized by the fact that a partition is formed.

PDP bulkhead formation method using photolithography is applied to the photosensitive bulkhead paste that can be photopolymerized by UV light on the glass substrate using an applicator, dried and then photo-masked to align the photomask. Is a method of obtaining a partition wall by dissolving with a developer using a difference in the solubility between the exposed and non-exposed areas of the exposed substrate, and removing the partition wall. There is this.

PDP photosensitive partition wall paste composition according to the present invention is prepared in the form of a paste by dispersing the partition wall powder in a liquid vehicle (vehicle), it is appropriate to include the partition wall powder 40 to 80% by weight, the vehicle 5 to 50% by weight. . If the partition powder is less than 40% by weight, it is difficult to form a partition of a desired height. When the partition powder is 80% by weight or more, the dispersibility and wettability of the partition wall powder are reduced, making it difficult to uniformly apply the partition. Here, the constituent components of the vehicle in the liquid phase consist of 3 to 15% by weight of the cellulose binder polymer, 15 to 60% by weight of the solvent, 5 to 40% by weight of the polyfunctional monomer or oligomer, 1 to 10% by weight of the photoinitiator, and 1 to 5% by weight of the additive. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Among the components of the photosensitive partition paste composition of the present invention, the binder polymer in the paste state having fluidity serves to uniformly disperse the partition powder, which is an inorganic material that forms the partition after firing, to control the viscosity of the paste, and to be entirely printed on the glass substrate. After the drying and exposure process, it plays a role of bonding the partition powder in the developing process, and after the partition pattern is formed, it is characterized by consisting of cellulose derivatives as an important element that plays a role of determining the firing temperature in the firing process.

In addition, the selection of the developing solvent during the photolithography process varies according to the selection of the binder polymer. Among the photosensitive barrier paste compositions according to the present invention, the binder polymers that can be developed in the organic solvent include cellulose nitrates, cellulose acetate, cellulose acetate butyrate, and the like. Cellulose esters and cellulose ethers such as ethyl cellulose, methyl cellulose may be used. In the case of ethyl cellulose, the degree of substitution of ethoxyl groups may be 5 to 60%, and in the case of less than 5% or more than 60%, miscibility and solubility with solvents are poor. In particular, ethyl cellulose having a degree of substitution of about 40 to 55% of the ethoxy group is suitable.

Meanwhile, as the binder polymer that can be developed in pure water in the photosensitive partition paste according to the present invention, hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, hydroxyethylmethyl cellulose, and the like may be used. Since solubility in water changes, it is required to select an appropriate molecular weight. Particularly, in the case of hydroxypropyl cellulose and hydroxy ethyl cellulose, the molecular weight can be used up to 5,000 to 1,200,000, but when it is 10,000 to 150,000, it is suitable as a binder polymer because of its excellent wettability and miscibility with the partition powder.

Such binder polymer is preferably contained in 3 to 15% by weight of the total composition of the vehicle, if the content is less than 3% by weight, there is a problem in rheological properties and dispersibility, and the coating process, if the content exceeds 15% by weight Since it is difficult to properly adjust the thickness, there is a problem in the application and control of the height of the partition wall.

Solvents used to dissolve the binder polymer of the photosensitive partition wall paste include 2-butoxy ethoxy ethanol, 2-ethoxy ethanol, 3-methoxy-3-methyl butanol (hereinafter referred to as 3 MMB), and alpha terpineol (α). alcohol compounds such as -terpineol); Polyalkylene glycol compounds such as butyl carbitol (hereinafter referred to as BC) and butyl carbitol acetate (hereinafter referred to as BCA); And a solvent such as N, N-dimethyl formamide (hereinafter referred to as DMF), N, N-dimethylacetamide (N, N-dimethyl acetamide), or a mixture of two or more thereof. Can be used.

In the photosensitive partition wall paste composition of the present invention, as the multifunctional monomer or oligomer, ethylene glycol diacrylate, methylene glycol bisacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate , Polyfunctional monomers such as dipentaerythritol hexaacrylate and polyfunctional oligomers such as epoxy acrylate, urethane acrylate and polyester acrylate can be used. Such polyfunctional monomers or oligomers are contained in 5 to 40% by weight of the total composition of the vehicle. If the content is less than 5% by weight, the crosslinking density is low, so that the formation of the partition is difficult. there is a problem.

As the photoinitiator, any photoinitiator capable of exhibiting excellent photoreaction in the ultraviolet wavelength range of 200 to 400 nm may be used as the photoinitiator among the photosensitive barrier paste composition components of the present invention. For example, 2,2-dimethoxy-2-phenylacetophenone (2,4-dimethoxy-2-phenyl acetophenone; hereinafter referred to as 'DMPA'), 1-hydroxy-cyclohexyl-phenyl ketone, para-phenylbenzophenone, benzyldimethyl ketal alone or two or more different photoinitiators Mixed photoinitiator mixed with the above can be used, and when the mixed photoinitiator is used, crosslinking ability can be exhibited at various wavelength ranges, thereby obtaining an excellent fluorescent film pattern. The photoinitiator content is preferably from 1 to 10% by weight of the total composition of the vehicle, the photopolymerization efficiency is lowered in the case of less than 1% by weight, the partition pattern may increase in the case of more than 10% by weight.

On the other hand, a separate additive can be added to improve the flow characteristics and process characteristics of the photosensitive partition wall paste of the present invention, the content of the additive is preferably 1 to 5% by weight of the total vehicle composition. Specific examples include photosensitizers such as benzophenone, acrylic dispersants such as Alcosperse 602-N, antifoaming agents such as BYK 307, leveling agents such as BYK 320, antioxidants such as Cygan geigy's Iganox 1010, and hydroquinones. Polymerization inhibitors such as monoethyl ether can be used, all of which can be understood to be well known to those skilled in the art that can be purchased and used commercially.

The bulkhead powder, which is an inorganic material, is slightly different depending on the composition and color of the upper layer and the lower layer, but generally Al ₂ O ₃ , CaO, Cr ₂ O ₃ , CuO, Fe ₂ O ₃ , K ₂ O, MnO, Na ₂ Mixtures of inorganic substances such as O, NiO, PbO, SiO ₂ , SnO ₂ , ZnO, ZrO ₂ , B ₂ O ₃ , TiO _2, and the like may be used.

The viscosity of the photosensitive partition wall paste composition for plasma display panels is suitably 2,000 to 1,000,000 cps. If the viscosity of the paste composition is lower than 2,000 cps, the spreading property on the glass substrate is not only difficult to apply the coating process, but also the storage stability of the partition paste is lowered. On the contrary, when the viscosity of the paste composition is higher than 1,000,000 cps, the coating property is poor and bubbles are generated. There may be a problem that the partition is not formed properly.

A plasma display panel partition wall forming method using the photosensitive partition wall paste composition according to the present invention comprises: applying a photosensitive partition wall paste composition on a glass substrate with a film having a thickness of 80 to 400 μm, as shown in FIG. 1; Drying step to dry at 50 ~ 200 ℃; An exposure step of exposing to ultraviolet light using a photomask on the dried film; Developing the patterned film with a developer to form a partition pattern; And a firing step of firing the formed partition pattern at 350 to 550 ° C. The coating process of the pattern forming step may be performed using a doctor blade and a bar, a screen printing and a spin coating, and an ink jet and a spray. ), But the printing application method is advantageous in controlling the appropriate thickness and rheological properties. The drying process may use a known drying method such as hot air or an infrared lamp, and the drying temperature is preferably dried for 10 to 90 minutes in a temperature range of 50 to 150 ° C.

The exposure process aligns a photomask on which the desired pattern is formed on the dried partition wall and irradiates ultraviolet rays with an intensity of 5 to 3000 J / cm 2. The exposure dose is advantageous in pattern formation in the range of 400 to 600 mJ / cm 2.

The development process is characterized by the use of spray (spray) is excellent in the development speed and the resolution of the pattern. The developer used in the developing step may vary depending on the type of binder polymer, but organic solvents such as methanol, ethanol, isopropyl alcohol, toluene, xylene, methyl ethyl ketone or pure water may be used.

In the firing step of the barrier rib forming method may be baked in a kiln for 5 to 120 minutes at a temperature of 350 to 550 ℃, it is preferable to bake for 30 to 90 minutes at a temperature of 450 to 550 ℃. If the firing temperature is low or the firing time is short, it is difficult to remove the binder polymer contained in the partition. If the firing temperature is too high or the firing time is long, the shape of the partition may be damaged.

Hereinafter, the present invention will be described in more detail with reference to preferred examples and comparative examples of the present invention. The following examples are intended to illustrate the invention and should not be understood as limiting the scope of the invention.

Example 1

0.75 g of ethyl cellulose was uniformly dissolved in 4.25 g of a mixed solvent of butyl carbitol (BC) and butyl carbitol acetate (BCA) (BC / BCA = 30/70 wt%) as a binder polymer, and pentae was a polyfunctional monomer. A vehicle was prepared by adding 1.0 g of ritthritol triacrylate (hereinafter referred to as PETA) and 1.0 g of tripropylene glycol diacrylate, adding 0.3 g of DMPA as a photoinitiator, and 0.03 g of hydroquinone monoethyl ether as an additive, and then stirring sufficiently.

10.97 g of partition powder was added thereto, and then uniformly dispersed using a kneader to prepare an organic solvent-developing photosensitive partition wall paste having a viscosity of 23,000 to 28,000 cps measured by a Brookfield viscometer.

The photosensitive partition wall paste was completely coated on a glass substrate with a film having a thickness of 300 μm using a printing machine, and then dried. The photomask was placed and exposed to light for 10 seconds at a light intensity of 10 mW / cm 2 using an ultraviolet exposure machine. The exposed glass substrate was developed by spraying with ethanol as a developing solvent, and then dried to obtain a partition pattern having a top width of 60 mm, a height of 150 μm, and a partition thickness of 230 μm.

As a result of examining the shape of the partition wall formed by the optical microscope, it was found that the partition wall was uniformly formed with a deviation within 0.5% of the average height from the partition wall.

The glass substrate in which the partition pattern was formed was calcined for 30 minutes at a firing temperature up to a maximum temperature of 450 ° C. to obtain a partition wall composed of only inorganic components.

Example 2

As a binder polymer, 1.00 g of hydroxypropyl cellulose was uniformly dissolved in 4.00 g of 3-methoxy-3-methyl butanol (3 MMB) solvent, 1.40 g of pentaerythritol triacrylate (PETA), 0.30 g of photoinitiator DMPA, and hydroquinone mono 0.03 g of ethyl ether was added and then stirred well to prepare a vehicle. 9.45 g of partition powder was added thereto, and then uniformly dispersed using a kneader to prepare a photosensitive partition wall paste capable of developing in pure water having a viscosity of 30,000 to 35,000 cps.

The photosensitive partition wall paste was completely coated on a glass substrate with a film having a thickness of 300 µm using a printing machine, and then dried. The photomask was placed thereon, and the photomask was exposed at a light intensity of 10 mW / cm 2 for 80 seconds. The exposed glass substrate was developed by spray using pure water as a developing solvent and then dried to obtain a partition pattern having a top width of the partition wall having a width of 50 µm, a height of 140 µm, and a partition gap of 250 µm.

As a result of examining the shape of the partition wall exposed by the optical microscope, the partition wall was uniformly formed with a deviation within 0.5% of the height.

The glass substrate in which the partition pattern was formed was calcined for 30 minutes at a firing temperature up to a maximum temperature of 450 ° C. to obtain a partition wall composed of only inorganic components.

Example 3

As a binder polymer, 1.00 g of hydroxyethyl cellulose was dissolved in 4.00 g of N, N-dimethylformamide solvent, 1.00 g of Everick Ebecryl-600, a polyfunctional UV oligomer, and 1.40 g of 2-hydroxyethyl acrylate, a functional monomer, A vehicle was prepared by adding 0.30 g of DMPA, a photoinitiator, and 0.03 g of hydroquinone monoethyl ether as an additive, followed by uniformly stirring. 6.43 g of partition powder was added thereto and then uniformly dispersed using a kneader to prepare a pure developing photosensitive partition wall paste having a viscosity of 21,500 to 26,500 cps.

The photosensitive partition wall paste was completely coated on a glass substrate with a film having a thickness of 300 μm using a printing machine, and then dried. The photomask was placed and exposed for 60 seconds at a light intensity of 10 mW / cm 2 using an ultraviolet exposure machine. After developing the exposed glass substrate by spray with pure water as a developing solvent, the barrier ribs irradiated with the optical microscope patterned into the shape of the barrier ribs were uniformly formed with a deviation within 0.5% of the average height. It was calcined for 30 minutes at the temperature to obtain a partition wall consisting of only inorganic components.

Comparative example

66.7 g of an acrylic copolymer (hereinafter referred to as poly (MMA-co-MAA)) containing methyl methacrylate (hereinafter referred to as MMA) and methacrylic acid (hereinafter referred to as MAA) in a 1: 1 molar ratio is referred to as N-methyl. It dissolved in 180 g of pyrrolidinone (hereinafter referred to as NMP) solvent to obtain a binder polymer solution. Here, 19.9 g of ethoxytrimetholol propane triacrylate (hereinafter referred to as TMPEOTA) as a polyfunctional monomer, 4.7 g of pentaerythritol triacrylate (PETA), and 7.6 g of DMPA as a photoinitiator, and hydroquinone monomethyl ether as an additive 1.1 g was added and stirred uniformly to obtain a photosensitive vehicle. When the bulkhead powder 60g was added and the bulkhead powder was dispersed using a kneader, the viscosity was high as 50,000 to 65,000 cps, and the bulking of the bulkhead powder was observed.

The photosensitive partition wall paste was completely coated on a glass substrate with a film having a thickness of 300 µm using a printing machine, and then dried. The photomask was placed thereon and exposed to a 60-second light intensity using an ultraviolet exposure machine with a light intensity of 10 mW / cm 2. The exposed glass substrate was developed by spraying with sodium carbonate solution (1% weight), which is an aqueous alkali solution, as a developing solvent and then dried, and then dried when the upper width was 60 µm, the height was 130 µm, and the partition gap was 280 µm. The bulkhead pattern was obtained, but partial dropout of the bulkhead was observed in about 20% of the total area.

When the glass substrate on which the partition pattern was formed was calcined for 30 minutes at the highest temperature of 450 ° C, some carbonized binder polymer remained on the partition observed by the scanning electron microscope, and when the firing temperature was raised to 510 ° C and fired for 30 minutes, the inorganic material was observed. A bulkhead composed of only components could be obtained. After firing, the bulkhead pattern also showed partial dropout of the bulkhead over about 20% of the total area, and the height of the formed bulkhead was more than 5% of the average.

Thus, the photosensitive partition wall paste made of acrylic resin as the binder polymer was calcined at a temperature of about 60 ° C. higher than the photosensitive partition wall paste made of the cellulose derivative of Example 1-3 as the binder polymer. As can be seen from the pyrolysis behavior of cellulose derivatives and acrylate resins by thermogravimetric analysis, acrylate binder polymers exhibit maximum decomposition temperature at about 394 ° C, whereas cellulose binder polymers exhibit maximum decomposition temperature at about 340 ° C. This is considered because of different characteristics.

As described in detail above, according to the present invention, a partition is formed by photolithography using a photosensitive partition wall paste obtained by mixing a cellulose derivative as a binder polymer and mixing a multifunctional monomer or oligomer, a photoinitiator, an additive, and a partition powder. In addition to the printing method and the sandblasting method, the plasma display panel having a higher resolution and uniform height can be formed, and the photosensitive partition paste using an acrylate-based resin as a binder polymer, unlike the partitioning powder, Excellent wettability and miscibility, uniform coating properties and low firing temperature.

Claims (7)

It comprises a partition powder and a liquid vehicle, the partition powder is composed of 40 to 80% by weight, the vehicle is composed of 5 to 50% by weight, the composition of the liquid vehicle is 3 to 15% by weight of the binder polymer of the cellulose derivative, 20 to 60 solvent A photosensitive bulkhead paste composition for plasma display panel comprising a weight%, 5 to 40% by weight of a polyfunctional monomer or oligomer, 1 to 10% by weight of a photoinitiator, and 1 to 5% by weight of an additive and capable of forming a partition by a photolithography method. The method of claim 1, The cellulose derivative is ethyl cellulose or methyl cellulose, the photosensitive partition wall paste composition for a plasma display panel. The method of claim 2, The photosensitive partition wall paste composition is a photosensitive partition wall paste composition for plasma display panels using ethanol or isopropyl alcohol as a developer in a developing step. The method of claim 1, The cellulose derivative is at least one water-soluble cellulose derivative selected from the group consisting of hydroxypropyl cellulose, hydroxypropylmethyl cellulose, hydroxyethylmethyl cellulose and hydroxyethyl cellulose. The method of claim 4, wherein The photosensitive partition wall paste composition is a photosensitive partition wall paste composition characterized by using pure water as a developing solution in a developing step. An application step of applying the photosensitive partition wall paste composition of claim 1 to a film having a thickness of 200 to 300 μm on a glass substrate; A drying step of heating and drying at 50 to 200 ° C. for 10 to 90 minutes; An exposure step of exposing to ultraviolet light using a photomask on the dried film; Developing the patterned film with a developer to form a partition pattern; And a firing step of firing the formed partition walls at 450 to 510 ° C. The method of claim 6, A method for forming a partition wall for a plasma display panel, wherein at least one selected from ethanol, isopropyl alcohol, and pure water is used as the developer.