KR20050104484A - Phosphor ink composition, and display panel comprising phosphor pattern formed using same - Google Patents

Abstract

The present invention relates to an ink composition comprising a phosphor, and according to the present invention, an aqueous phosphor ink composition comprising a nano-sized phosphor powder, a silane coupling agent, a dispersant and an ionizing agent uses a nano-sized phosphor and uses a binder polymer. Since it does not include, there is no nozzle clogging during spraying by the inkjet method, it is environmentally friendly, has excellent dispersibility, and there is no residual carbon after firing, it can be advantageously used as a fluorescent film material for PDP.

Description

A display panel including a phosphor ink composition and a phosphor film using the same, the present invention relates to a display panel including a phosphor film and a phosphor film using the same.

The present invention relates to an ink composition comprising a phosphor, and more particularly, to an ink composition that can be advantageously used for manufacturing a fluorescent film for a plasma display panel (PDP) by an inkjet method.

The plasma display panel is a flat panel display device using a phenomenon in which vacuum ultraviolet rays (about 147 nm in wavelength) emitted from plasma generated when the inert gas is discharged collide with the fluorescent film and change into red, green, and blue light in the visible region. It is attracting attention as one of the next generation displays such as high-definition television (HDTV) in that full color display, fast response speed, wide viewing angle, and easy to implement a large display device of 40 inches or more are possible.

PDPs are classified into direct current (DC) type and alternating current (AC) type, and double AC type is divided into counter discharge type and surface discharge type according to the electrode structure of discharge cell, and the opposite discharge type is phosphor deterioration due to ion shock. Due to the problem that the lifespan is shortened, the surface discharge type can solve the problem of the opposite discharge type structure by collecting the discharge to the opposite side of the phosphor to minimize the degradation of the phosphor and is currently adopted in most PDPs.

The cross-section of the surface discharge type AC PDP is shown in FIG. 1. As shown in FIG. 1, in the surface discharge type AC PDP, the rear substrate 10, the addresser electrode 11, the white dielectric 12, the partition 13, and the like form a rear substrate, and the front substrate 14 ), The transparent electrode 15, the bus electrode 16, the transparent dielectric layer 17, the dielectric protective layer 18, and a black stripe form a front plate. In addition, red, green, or blue phosphors 19 for realizing the color of the PDP are disposed on the front plate in the case of a transmissive type and between partition walls 13 of the back plate as shown in the case of a reflective type.

Conventionally, a fluorescent film of an AC plasma display panel is formed by applying a phosphor paste between partitions of a lower plate by a photolithography method or a printing method as shown in Figs. 2A and 2B, respectively. First, the manufacturing process of the PDP fluorescent film by the photolithography method will be described in detail. For example, as shown in FIG. 2A, first, a red photosensitive phosphor paste is applied using a screen printer, and then a photomask ( When the UV exposure is performed using a photomask, a portion of the UV exposure is not etched after development by an aqueous alkali solution due to photocrosslinking, and a red fluorescent film is formed on the portion not subjected to UV exposure. In this manner, green and blue fluorescent films may also be successively formed. However, the process of forming the fluorescent film by the etching method is disadvantageous in that it is complicated and there is a lot of material loss.

In addition, the manufacturing process of the PDP fluorescent film by the printing method will be described in detail. For example, as shown in FIG. 2B, when the red phosphor paste is applied using a screen printing machine with a pattern, a red phosphor film is formed between the partition walls. In this manner, green and blue fluorescent films may also be successively formed. The process of forming a fluorescent film by the printing method has a disadvantage in that the loss of material is small but it is difficult to control the precision and width of the fluorescent film pitch, which is unsuitable for the production of high definition and large screen PDPs.

Therefore, in the manufacture of the PDP fluorescent film, an inkjet method capable of producing a low-loss material, a simple process, and a high-definition and large-screen PDP can be manufactured. Specifically, as shown in FIGS. A process for producing a fluorescent film by a method including coating with the same is disclosed in Korean Patent Publication No. 2002-93921.

However, when forming the fluorescent film by the inkjet method, when using a conventional phosphor ink composition, the average particle size of the phosphor contained in the ink composition is 0.5 to 7 ㎛ to block the nozzle inlet during continuous ink ejection; In addition, binder polymer is essentially included in order to obtain the viscosity required in the screen printing process, which requires a long firing time in manufacturing the fluorescent film, and remains in the form of carbon after firing, thereby lowering the fluorescent property of the fluorescent film. There is a problem.

Accordingly, an object of the present invention is not to block the nozzle inlet during the injection by the piezoelectric inkjet method, does not contain a binder polymer, excellent dispersibility, which can be advantageously used for the production of a fluorescent film for PDP, phosphor ink It is to provide a composition.

In order to achieve the above object, the present invention provides an aqueous phosphor ink composition comprising a) nano-sized phosphor powder, b) dispersant, c) silane coupling agent and d) ionizer.

In addition, the present invention provides a display panel including a fluorescent film formed using the phosphor ink composition.

Hereinafter, the present invention will be described in more detail.

Characteristic of the phosphor ink composition of the present invention is to use a nano-sized phosphor powder to enable the discharge through the piezoelectric inkjet nozzle, and unlike the conventional ink composition does not contain a binder polymer, low viscosity and plasticity There is no carbon remaining afterwards.

Hereinafter, each component is demonstrated.

The phosphor powder (component a) used in the present invention preferably has an average particle size in the range of 50 to 500 nm. The nanoscale phosphor powder can be prepared, for example, by an inverse emulsion method as schematically shown in FIG. 4 [JW Vanderhoff, EB Bradford, MLTarkowski, Adv. Chem. Der, 34, 32 (1962). Specifically, a water dispersion containing a metal source (e.g. Zn (NO ₃ ) ₂ .6H ₂ O, MnCl ₂ , Na ₂ SiO ₃ , etc.), a surfactant dissolved in an organic solvent (e.g. isooctane, etc.) (e.g. cetyltrimethyl) Centrifuged separation of a slurry solution containing ammonium bromide, tween 20, etc. and cosurfactant (e.g., n-butanol, etc.) to obtain a phosphor sol, and the resulting phosphor sol is, for example, a mixed solution of ethanol and distilled water. (1: 1 volume) to remove residual surfactant, followed by calcination (900-1200 ℃) and grinding process to obtain a nano-sized phosphor powder. Cosurfactants used in the inverse emulsion method can further reduce the size of the micelle (micelle) formed by interaction with the surfactant.

When nano-sized green phosphor (Zn ₂ SiO ₄ : Mn) powder is prepared by the inverse emulsion method, for example, distilled water and an organic solvent are preferably used in a ratio (volume ratio) of 1: 4 to 1: 8. It is preferable to use distilled water and surfactant in the ratio (molar ratio) of 10: 1-1: 17, and it is preferable to use cosurfactant and surfactant in the ratio (weight ratio) of 0.5: 1-1: 1. , Metal sources Zn (NO ₃ ) ₂ .6H ₂ O, MnCl ₂ and Na ₂ SiO ₃ are preferably used in a ratio (molar ratio) of about 2: 1: 1.

In the present invention, the nano-sized phosphor powder is preferably included in an amount of 10 to 30% by weight based on the total weight of the ink composition.

The dispersant (component b) is added to increase the dispersion stability of the nano-sized phosphor powder, and the dispersant used in the present invention is apolar, and functional groups (eg, phthalimide groups, hydrides) that can adsorb to the phosphor powder. Hydroxy group, sorbitan laurate group, sorbitan stearate group, etc.) and a compound containing functional groups (e.g., polyoxyethylene group, octyl group, octadecyl group, cetyl group, etc.) inducing steric hindrance Polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan triol Latek, byk-192, byk-180, byk-184, etc., from BYK-chemie, and the like, in amounts ranging from 3 to 10 weight percent based on the total weight of the ink composition To be included as is preferred.

The silane coupling agent (component c) is added to give a steric hindrance effect, the silane coupling agent used in the present invention is a tree capable of reacting with -OH groups present on the surface of the nano-sized phosphor powder Compounds containing an alkoxysilane group and an aminoalkyl group and ionizable with an acid or a base can be used. Specifically, aminopropyltriethoxysilane, aminopropyltrimethoxysilane, aminopropylmethyldiethoxysilane, aminopropylmethyldimethoxysilane, aminoethylaminopropyltrimeth Methoxysilane (aminoethylaminopropyltrimethoxysilane), aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltrie Diethylenetriaminopropyltriethoxysilane, diethylenetriaminopropylmethyldimethoxysilane, diethylenetriaminopropylmethyldiethoxysilane methyldiethoxysilane) and the like, and are preferably included in an amount ranging from 3 to 10% by weight based on the total weight of the ink composition.

The ionizer (component d) is a substance capable of reacting with an acidic or basic silane coupling agent introduced on the surface of phosphor particles to form an anion or a cation, and capable of reacting with a basic functional group of the silane coupling agent to form a cation. As the cation donor, one or more selected from acidic compounds such as acetic acid, toluene sulfonic acid, benzene sulfonic acid, alkyl halide, dimethyl sulfate and the like can be used; As the anion imparting agent capable of reacting with the acidic functional groups of the silane coupling agent to form anions, one or more selected from basic compounds such as ammonia, pyridine, piperidine, picoline, and the like may be used. The ionizer is preferably included in an amount in the range of 1 to 5% by weight based on the total weight of the ink composition, and 0.01 to 3 moles per 1 mole of the silane coupling agent.

When the nano-sized phosphor in which the silane coupling agent is introduced to the particle surface as described above is treated with an ionizing agent, cations or anions are formed on the surface to minimize aggregation of the phosphor particles by charge repulsion between the phosphor particles in an aqueous dispersion medium. This prevents clogging of nozzles when dispersing with piezo type inkjet equipment.

The phosphor ink composition of the present invention can be prepared by adding a dispersing agent and a silane coupling agent to the nano-sized phosphor powder and solubilizing with an aqueous medium, and then adding an ionizing agent, as schematically shown in FIG. After adding 0.4 to 0.6 mm zirconia beads to the aqueous solution of the composition and uniformly milling for 6 to 48 hours using a bead mill equipment, the phosphor ink for PDP having excellent dispersibility according to the present invention can be prepared. have.

Since the aqueous phosphor ink composition according to the present invention is aqueous and is free of volatilization such as organic solvents, it is environmentally friendly, and does not contain a binder polymer, which can shorten the firing process time when manufacturing a PDP fluorescent film using the same, and thus deteriorate due to the heat of the contained phosphor. Not only can be prevented, there is no residual carbon after firing, it can be advantageously used for the production of PDP fluorescent film having excellent fluorescence properties and long life. In particular, since it contains nano-sized phosphor powder, there is little material loss and there is no nozzle clogging during application by the inkjet method, which is advantageous for forming a large area and high resolution phosphor film.

The PDP fluorescent film manufacturing process using the inkjet method may include: obtaining a phosphor pattern by an inkjet method using phosphor inks such as blue, green, and red on a lower glass substrate of a PDP having partition walls; Drying after heating for 5 to 30 minutes at a temperature in the range of 50 to 130 ° C .; And baking the formed fluorescent film at a temperature of 400 to 600 ° C.

Hereinafter, the present invention will be described in more detail based on the following Examples and Comparative Examples. However, the following examples are not intended to limit the invention only.

Preparation of Nano-sized Green Phosphor Powder by Inverse Emulsion Method

Preparation Example 1

6.2 g of Zn (NO ₃ ) ₂ .6H ₂ O and 0.1 g of MnCl ₂ were dissolved in 36.7 g of distilled water to make solution I, 1.3 g of Na ₂ SiO ₃ was dissolved in 36.7 g of distilled water to make solution II, 109 g of cetyltrimethyl ammonium bromide (CTAB), a surfactant, was dissolved in 203 g of isooctane to prepare solution III, which was prepared in a separate container. After dividing Solution III into two vessels in half, Solution I and Solution II were added dropwise to each vessel to obtain Solutions IV and V. Subsequently, 145.8 g of n-butanol as a co-surfactant was added dropwise to Solutions IV and V, respectively, and the solution V was added dropwise to Solution IV while stirring to obtain a slurry liquid. The slurry solution was centrifuged (10 times, 5000 rpm) to obtain a phosphor sol, which was placed in a mixture of ethanol / distilled water (1: 1, v / v), sonicated and stirred several times, to be present as impurities. After removing the surfactant, the resultant was calcined at 900 ° C. for 1 hour to obtain 1.2 g of green phosphor Zn ₂ SiO ₄ : Mn powder.

A scanning electron micrograph of the phosphor powder obtained above is shown in FIG. 5A, from which it can be seen that the prepared green phosphor powder has a nano size of about 50 to 300 nm.

Preparation Example 2

6.2 g of Zn (NO ₃ ) ₂ .6H ₂ O and 0.1 g of MnCl ₂ were dissolved in 36.7 g of distilled water to make solution I, 1.3 g of Na ₂ SiO ₃ was dissolved in 1.3 g of distilled water to make solution II, 100.7 g of Tween 20 (Aldrich), a surfactant, was dissolved in 55.3 g of mineral oil, and prepared as a solution III, respectively. After dividing Solution III into two vessels in half, Solution I and Solution II were added dropwise to each vessel to obtain Solutions IV and V. Subsequently, 158 g of n-butanol as a co-surfactant was added dropwise to Solutions IV and V, respectively, and the solution V was added dropwise to Solution IV while stirring, thereby obtaining a slurry liquid. The slurry solution was centrifuged (10 times, 5000 rpm) to obtain a phosphor sol, which was placed in a mixture of ethanol / distilled water (1: 1, v / v), sonicated and stirred several times, to be present as impurities. After removing the surfactant, the resultant was calcined at 1100 ° C. for 1 hour to obtain 1.5 g of green phosphor Zn ₂ SiO ₄ : Mn powder.

A scanning electron micrograph of the phosphor powder obtained above is shown in FIG. 5B, from which it can be seen that the prepared green phosphor powder has a nano size of about 50 to 500 nm.

Preparation of Phosphor Inks

Example 1

To 13.5 g of the phosphor powder obtained in Preparation Example 1, 6.5 g of BYK-192 (BYK Chemi) as a dispersant and 6.5 g (0.03 mol) of aminopropyltriethoxysilane as a silane coupling agent were mixed and mixed, followed by 70 g of water and 3.5 g (0.06 mole) of acetic acid was added sequentially. Then, 0.4 mm of zirconia beads were added to the obtained mixture and uniformly milled for 48 hours using a bead mill equipment to prepare an ink including the aqueous phosphor ink composition according to the present invention. The particle size distribution of the prepared phosphor ink was measured using an electrophoretic light scattering spectrophotometer (ELS-8000), and the results are shown in FIG. 7. 7, it can be seen that the average particle size of the prepared phosphor ink is about 220.7 nm.

The components and contents included in the phosphor ink prepared in Example 1 are summarized in Table 1 below.

ingredient Content (g) H ₂ O 70 Dispersant (BYK-192) 6.5 Silane coupling agent (aminopropyltriethoxysilane) 6.5 Ionizer (acetic acid) 3.5 Nano-sized Phosphor Powder (Preparation Example 1) 13.5

Example 2

A phosphor ink having an average particle size of about 358 nm was prepared by the same method as Example 1 with the ingredients and contents shown in Table 2 below.

ingredient Content (g) H ₂ O 55.5 Dispersant (BYK-180) 9.2 Silane coupling agent (3- (2-aminoethyl) aminopropyltriethoxysilane) 10.0 Ionizer (acetic acid) 3.8 Nano-sized Phosphor Powder (Preparation Example 1) 21.5

Example 3:

A phosphor ink having an average particle size of about 415 nm was prepared by the same method as Example 1 with the ingredients and contents shown in Table 3 below.

ingredient Content (g) H ₂ O 58 Dispersant (BYK-184) 7.0 Silane Coupling Agent (Aminopropylmethyldiethoxysilane) 8.8 Ionizer (acetic acid) 3.7 Nano-sized Phosphor Powder (Preparation Example 2) 22.5

Example 4

A phosphor ink having an average particle size of about 390 nm was prepared by the same method as Example 1 with the ingredients and contents shown in Table 4 below.

ingredient Content (g) H ₂ O 54 Dispersant (BYK-192) 10 Silane Coupling Agent (Aminomethylaminopropylethyldiethoxysilane) 4.5 Ionizer (acetic acid) 1.5 Nano-sized Phosphor Powder (Preparation Example 2) 30

Comparative Example 1: Preparation of Phosphor Ink

A phosphor ink was prepared by the same method as Example 1 with the ingredients and contents shown in Table 5 below.

ingredient Content (g) Solvent (water) 67.5 Binder Polymer Resin (Polyallylamine) 2.5 3.5 μm size phosphor powder 20 Dispersant (BYK-192) 10

Fluorescent film manufacturing

Example 5

The phosphor ink prepared in Example 1 was applied to a glass substrate on which a partition wall was formed using a piezoelectric inkjet device, dried at 90 ° C. for 10 minutes, and then put into a box-type kiln, which was baked at 450 ° C. for 30 minutes to remain. The organic component was removed to prepare a fluorescent film.

Examples 6-8

Using the phosphor inks prepared in Examples 2 to 4, respectively, a process similar to that in Example 5 was performed to prepare a fluorescent film.

Comparative Example 2

Using a phosphor ink prepared in Comparative Example 1, except that it is baked at 450 ℃ for 50 minutes, a similar process to Example 5 was carried out to produce a fluorescent film.

Subsequently, after cooling the fluorescent film prepared in Example 5 and Comparative Example 2 to room temperature, the substrate was irradiated with vacuum ultraviolet (147 nm) to obtain the luminance and emission spectrum of green light generated from the fluorescent film by PR-704 (Photoresearch Co.) Was measured, and the results are shown in FIG. From FIG. 8, it can be seen that the luminance of the fluorescent film manufactured using the ink composition of the present invention is improved compared to the luminance of the fluorescent film manufactured using the conventional phosphor ink composition including the binder polymer resin of Comparative Example 1.

The aqueous phosphor ink composition according to the present invention can be advantageously used for producing a high-resolution PDP fluorescent film having high brightness because there is no nozzle clogging, excellent dispersibility, environmentally friendly, and no residual carbon after firing, when the inkjet method is used. have.

1 is a schematic diagram showing a cross section of a conventional surface discharge type AC PDP;

2a and 2b is a process diagram schematically showing a conventional fluorescent film manufacturing process using a phosphor paste,

3a to 3d is a process diagram schematically showing a fluorescent film manufacturing process using a conventional inkjet method,

Figure 4 is a process diagram schematically showing a nano-size phosphor powder synthesis process used in the present invention,

5a and 5b are electron micrographs of the nano-sized phosphor powder used in the present invention,

6 is a process diagram schematically showing a manufacturing process of the aqueous phosphor ink composition according to the present invention,

7 is a graph showing the particle size distribution of the aqueous phosphor ink composition according to the present invention,

8 is a light emission spectrum of measuring the luminance of the fluorescent film prepared in Example 5 and Comparative Example 2 of the present invention.

<Description of Signs of Major Parts of Drawings>

10: back substrate 11: address electrode 12: white dielectric

13: partition 14: front substrate 15: transparent electrode

16: Bus electrode 17: Transparent dielectric film 18: Dielectric protective film

19: phosphor

Claims (8)

An aqueous phosphor ink composition comprising a) a nanosized phosphor powder, b) a dispersant, c) a silane coupling agent, and d) an ionizer. The method of claim 1, The composition, characterized in that the average particle size of the nano-sized phosphor powder ranges from 50 to 500 nm. The method of claim 1, 10 to 30% by weight of nano-sized phosphor powder, 3 to 10 weight percent dispersant, 3 to 10% by weight of silane coupling agent, 1 to 5% by weight ionizer, and A composition comprising the remaining amount of water. The method of claim 1, A composition comprising 0.01 to 3 moles of ionizer per mole of silane coupling agent. The method of claim 1, In the group consisting of polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate A nonpolar compound having at least one functional group selected. The method of claim 1, Silane coupling agents include aminopropyltriethoxysilane, aminopropyltrimethoxysilane, aminopropylmethyldiethoxysilane, aminopropylmethyldimethoxysilane, aminoethylaminopropyltrimeth Methoxysilane (aminoethylaminopropyltrimethoxysilane), aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltrie Diethylenetriaminopropyltriethoxysilane, diethylenetriaminopropylmethyldimethoxysilane, and diethylenetriaminopropylmethyldiethoxysilane (diethylenetriaminop ropylmethyldiethoxysilane) composition, characterized in that at least one selected from the group consisting of. The method of claim 1, The ionizing agent is at least one selected from acetic acid, toluene sulfonic acid, benzene sulfonic acid, alkyl halide, dimethyl sulfate, ammonia, pyridine, piperidine and picoline. A display panel comprising a fluorescent film formed using the aqueous phosphor ink composition according to any one of claims 1 to 7.