KR20100067448A - Fluorescent paste - Google Patents

Abstract

PURPOSE: A fluorescent paste is provided to secure coating uniformity of fluorescent substance by controlling the viscosity increase of the fluorescent paste by including a fluorescent powder, a binder, magnesium oxide powder, a first solvent, and a second solvent. CONSTITUTION: A fluorescent paste comprises a fluorescent powder 30-50 wt%, magnesium oxide(MgO) powder 1-10 wt%, first solvent 9-45 wt%, and second solvent 15-51 wt%. The first solvent is N-methyl-2-pyrrolidone and the second solvent is dipropylene glycol n-butyl ether. The particle diameter of the fluorescent powder is 0.2-5 microns. The binder is a cellulose-based resin. The fluorescent powder includes (Y,Gd,Eu)BO_3 and αFe_2O_3.

Description

Phosphor Paste

The present invention relates to a phosphor paste, and more particularly, N-methyl-2-pyrrolidone (NMP) as the first solvent, dipropylene glycol n-butyl ether as the second solvent It relates to a phosphor paste containing (Dipropylene Glycol n-butyl Ether, DPnB).

In general, a plasma display panel (PDP) injects a discharge gas into a discharge cell separated by a partition wall, and is caused by an energy difference when ultraviolet rays generated during plasma emission excite phosphors and return to a ground state. A display device using a light emission phenomenon of visible light. Since the phosphor is made of a solid powder, it is mixed with an organic material and coated by a printing method used to prepare a paste.

On the other hand, the phosphors of the plasma display panel have different characteristics and different surface charge potentials, and thus, discharge characteristics are lowered, and in particular, discharge voltages increase with increasing definition, and efficiency and luminance may be lowered.

In order to lower the discharge voltage and increase the efficiency, there is an attempt to mix MgO in the phosphor paste. In the case of mixing MgO in the phosphor paste, the black characteristic can be lowered by adjusting the voltage characteristic and adjusting the driving waveform, thereby improving the clearing ratio. However, the OH ⁻ group is bonded to the highly polar MgO to increase the viscosity of the phosphor paste.

In general, the phosphor paste is in a form adapted to the dispensing process, and uniform viscosity and paste properties are required to secure dispensing properties. If the viscosity of the phosphor paste is increased, the uniformity of dispensing coating is inferior, and if it is diluted with a solvent (Let down process) to decrease the viscosity, the content of inorganic solids relative to the total weight of the phosphor paste is relatively reduced to secure the thickness of the phosphor coating. Can be difficult.

An object of the present invention is to provide a phosphor paste which can suppress the viscosity increase of the phosphor paste and ensure the phosphor coating uniformity.

Phosphor paste according to the present invention for achieving the above object comprises a phosphor powder, a binder, magnesium oxide (MgO) powder, a first solvent and a second solvent, the first solvent is N-methyl-2-pyrroli D-N-methyl-2-pyrrolidone (NMP), and the second solvent is Dipropylene Glycol n-butyl Ether (DPnB).

In addition, the phosphor paste according to the present invention for achieving the above object, the phosphor powder 30 to 50 wt%, the binder 5 to 10 wt%, magnesium oxide (MgO) powder 1 to 10 wt%, the first solvent 9 to 45 wt% and 15 to 51 wt% of the second solvent.

According to the present invention, the viscosity rise of the phosphor paste can be suppressed to ensure the uniformity of phosphor coating.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

The phosphor paste according to an embodiment of the present invention may include a phosphor powder, a binder, magnesium oxide (MgO) powder, and a solvent.

The phosphor powder may be any one of red, green and blue phosphor powders, and in red, Y ₂ O ₃ : Eu, YVO ₄ : Eu, (Y, Gd) BO ₃ : Eu, Y ₂ O ₃ S: Eu and γ-Zn ₃ (PO ₄ ) ₂ : Mn, (Zn, Cd) S: Ag + In ₂ O ₃ , Y (P, V) O ₄ : Eu and the like.

In addition, in green, Zn ₂ GeO ₂ : Mn, BaAl ₁₂ O ₁₉ : Mn, Zn ₂ SiO ₄ : Mn, LaPO ₄ : Tb, ZnS: Cu, Al, ZnS: Au, Cu, Al, (Zn, Cd) S: Cu, Al, Zn ₂ SiO ₄ : Mn, As, Y ₃ Al ₅ O ₁₂ : Ce, CeMgAl ₁₁ O ₁₉ : Tb, Gd ₂ O ₂ S: Tb, Y ₃ Al ₅ O ₁₂ : Tb, ZnO: Zn, (Y, Gd) BO ₃ : Tb, (Ba, Sr, Mg) O.aAl ₂ O ₃ Mn, and the like, and Sr ₅ (PO ₄ ) ₃ Cl: Eu, BaMgAl ₁₄ O _{23 as} blue. : Eu, BaMgAl ₁₆ O ₂₇ : Eu, BaMg ₂ Al ₁₄ O ₂₄ : Eu, CaMgSi ₂ O ₆ : Eu, Y ₂ SiO ₃ : Ce, BaMgAl ₁₀ O ₁₇ : Eu, and the like.

It is preferable that the particle diameter of such fluorescent substance powder is 0.2-5 micrometers. When the particle size of the phosphor powder is smaller than 0.2 µm, the aggregation of the phosphor powder is likely to occur, and the surface is activated, and thus, chemical reaction with other components such as a binder can be caused. On the other hand, when the particle diameter is larger than 5 μm, the fluorescent film may become nonuniform or, accordingly, the luminance may be nonuniform, which is not preferable.

On the other hand, if the content of the phosphor powder is less than 30wt%, the coating thickness of the paste required to obtain the desired film thickness becomes thick, so that color mixing may occur between adjacent discharge cells, whereas the content of the phosphor powder exceeds 50wt%. The viscosity of the phosphor paste may increase, which may reduce dispensing coating uniformity. Therefore, the phosphor powder is preferably contained in 30 to 50wt%.

The binder functions as a binder of each component before firing and is a cellulose type such as ethyl cellulose, methyl cellulose, nitrocellulose, cellulose acetate, cellulose propionate, cellulose butyrate, hydroxy cellulose, and methyl hydroxy cellulose. Resins and the like can be used.

In addition, the content of the binder is preferably 5 to 10wt%. If the content of the binder is less than 5wt%, the bonding strength of the fluorescent film may be lowered. If the amount of the binder is greater than 10wt%, the phosphor content in the fluorescent film may be relatively reduced, resulting in deterioration of characteristics such as color purity.

Magnesium oxide (MgO) powder is added to reduce the surface potential difference of the phosphor for each color to lower the discharge nonuniformity and increase the secondary electron emission coefficient to prevent the discharge voltage and prevent high temperature discharge.

Such magnesium oxide powder may be added at 1 to 10 wt%. When the amount of magnesium oxide powder added is less than 1wt%, the effect of adding magnesium oxide is insignificant, and when it is added in excess of 10wt%, the ratio of the supplementary magnesium oxide of the phosphor increases, so that the overall brightness may be reduced.

In addition, the size of the magnesium oxide powder particles is preferably 2nm to 10㎛. This is because when the size of magnesium oxide powder particles is less than 2 nm or exceeds 10 µm, the workability of the paste is lowered, which is not preferable.

However, the magnesium oxide is Mg ^{2 +} and O ^{2 -} to raise the viscosity of the phosphor paste to the reaction with Mg (OH) ₂ group is bonded to ^- the nature and strong OH of ethyl cellulose binder in a Mg ^{2 +} ionized. If the viscosity of the phosphor paste is increased, the uniformity of dispensing coating is inferior, and when dilution with a solvent (Let down process) to decrease the viscosity, the content of inorganic solids relative to the total weight of the phosphor paste is relatively decreased, thereby reducing the thickness of the phosphor coating. It can be difficult to secure.

Accordingly, the phosphor paste according to the present invention can prevent the increase in the viscosity of the phosphor paste even if magnesium oxide is added by adding a strong polar solvent.

First, the solvent may be included in the phosphor paste at 30 to 60 wt%. When the amount of the solvent contained is less than 30 wt%, the viscosity of the phosphor paste may be too high, resulting in uneven phosphor coating thickness. On the other hand, when the content of the solvent is greater than 60wt%, the content of the phosphor per unit volume is too low, which is not preferable because the luminance is lowered.

On the other hand, the solvent contained in the phosphor paste according to the present invention is a first solvent of N-methyl-2-pyrrolidone (NMP) and dipropylene glycol n-butyl ether (Dipropylene Glycol n- butyl Ether, DPnB), the second solvent.

The first solvent is N- methyl-2-pyrrolidone has the structural formula below, because of the strong polar than the OH groups in the binder terminal OH ^- and to prevent the Mg ^{2 +} a reaction preventing viscosity increase of the phosphor paste can do.

However, in the case of including N-methyl-2-pyrrolidone as the first solvent alone, the viscosity of the phosphor paste may be too low because the solubility of the organic polymer is too high. Therefore, it is preferable to mix and contain the dipropylene glycol n-butyl ether which is a 2nd solvent.

In this case, when the amount of the first solvent is less than 9wt%, the effect of preventing the viscosity increase of the phosphor paste is insignificant, whereas when it exceeds 45wt%, the viscosity of the phosphor paste is rather low.

Table 1 below shows the composition of the phosphor paste to which various solvents are added and the viscosity increase results accordingly. Ethyl cellulose binder was used as the binder. In addition, the red phosphor is (Y, Gd, Eu) BO ₃ And αFe ₂ O ₃ , the blue phosphor is (Ba, Sr, Eu) MgAl ₁₀ O ₁₇ And CoAl ₂ O _4, a green phosphor ^{_{Zn 2 SiO 4: Mn 2 +}} , Al ₂ O ₃ And YBO _3: it was used Tb ₃ ^+. In addition, all units are wt% unless there is particular notice here.

Phosphor
powder MgO
powder bookbinder
solvent Viscosity rise
NMP DPnB BC BCA Example 1 Red 44 2.2 7.6 23.1 23.1 14 days initial viscosity Example 2 Blue 31 1.55 10 28.25 29.2 14 days initial viscosity Example 3 Green 48 2.4 7.6 21 21 14 days initial viscosity Comparative Example 1 Red 44 4.4 7.6 44 30% after 12hr Comparative Example 2 Blue 31 1.55 10 28.25 29.2 120% increase after 12hr Comparative Example 3 Blue 31 3.5 9 28 28.5 200% increase after 12hr Comparative Example 4 Blue 31 1.55 10 29.2 28.25 130% after 12hrs Comparative Example 5 Green 48 2.4 7.6 21 21 15% increase after 12hr Comparative Example 6 Green 48 2.4 7.6 21 21 30% increase after 12hr

NMP: N-methyl-2-pyrrolidone

DPnB: Dipropylene Glycol n-butyl Ether

BC: Butylene Carbonate

BCA: Butyl Carbitol Acetate

If the viscosity of the phosphor paste is increased by more than 10% compared to the initial viscosity, the uniformity of dispensing coating is inferior. In Table 1 above, it was determined whether the viscosity was increased by 10% compared to the initial viscosity for 14 days.

In Examples 1 to 3 of Table 1, N-methyl-2-pyrrolidone and Dipropylene Glycol n-butyl Ether are mixed as a solvent in a phosphor paste containing red, green, and blue phosphor powder, respectively. It can be seen that the initial viscosity is maintained for 14 days.

In Comparative Example 1, when N-methyl-2-pyrrolidone was used alone as a solvent, the viscosity of the phosphor paste was lowered, because the solubility of the organic polymer in the phosphor paste was too high.

The compositions of the solvents of Comparative Examples 2 to 6 do not contain N-methyl-2-pyrrolidone, and are different from Examples 1 to 3. Comparative Examples 2 to 6 show the result that the viscosity of the phosphor paste is increased in all cases. This, it can be seen that the OH ⁻ group of the ethyl cellulose binder is bonded to Mg ^{2 +} and did not prevent the reaction with Mg (OH) ₂ .

Therefore, the phosphor paste including MgO according to the present invention can prevent the increase in viscosity of the phosphor paste by using a mixture of N-methyl-2-pyrrolidone and Dipropylene Glycol n-butyl Ether.

On the other hand, the phosphor paste of this invention can add photosensitive components, such as a photosensitive monomer, a photosensitive oligomer, and a photosensitive polymer, and additive components, such as a photoinitiator, a sensitizer, antioxidant, a ultraviolet absorber, and a polymerization inhibitor.

1 is a diagram illustrating a structure of a PDP including a phosphor film formed of a phosphor paste according to an embodiment of the present invention.

Referring to the drawings, the plasma display panel 100 includes a scan electrode 111, a sustain electrode 112, a sustain electrode pair formed on the upper substrate 110, and an address electrode 122 formed on the lower substrate 120. It includes.

The sustain electrode pairs 111 and 112 generally include transparent electrodes 111a and 112a and bus electrodes 111b and 112b formed of indium tin oxide (ITO), and the bus electrodes 111b and 112b) may be formed of a metal such as silver (Ag) or chromium (Cr) or a stack of chromium / copper / chromium (Cr / Cu / Cr) or a stack of chromium / aluminum / chromium (Cr / Al / Cr). .

The bus electrodes 111b and 112b are formed on the transparent electrodes 111a and 112a to reduce the voltage drop caused by the transparent electrodes 111a and 112a having high resistance.

Meanwhile, between the transparent electrodes 111a and 112a of the scan electrode 111 and the sustain electrode 112 and the bus electrodes 111b and 111c, external light generated from the outside of the upper substrate 110 is absorbed to reduce reflection. The black matrix (BM, 115) is arranged to serve as a light blocking function and to improve the purity and contrast of the upper substrate 110.

The black matrix 115 is formed on the upper substrate 110. The first black matrix 115, the transparent electrodes 111a and 112a, and the bus electrodes 111b and 112b are formed at positions overlapping the partition wall 121. The second black matrices 111c and 112c may be formed therebetween.

Here, the first black matrix 115 and the second black matrices 111c and 112c, also referred to as black layers or black electrode layers, may be simultaneously formed and physically connected in the formation process, or may not be simultaneously formed to be physically connected. .

In addition, when physically connected and formed, the first black matrix 115 and the second black matrix 111c and 112c may be formed of the same material, but may be formed of another material when the physically separated material is formed.

The upper dielectric layer 113 and the passivation layer 114 are stacked on the upper substrate 110 having the scan electrode 111 and the sustain electrode 112 side by side. Charged particles generated by the discharge are accumulated in the upper dielectric layer 113, and a function of protecting the sustain electrode pairs 111 and 112 may be performed.

The passivation layer 114 protects the upper dielectric layer 113 from sputtering of charged particles generated during gas discharge, and increases emission efficiency of secondary electrons.

The address electrode 122 is formed in a direction crossing the scan electrode 111 and the sustain electrode 112.

The lower dielectric layer 124 and the partition wall 121 are formed on the lower substrate 120 on which the address electrode 122 is formed.

The lower dielectric layer 124 is electrically condensed to protect the address electrode 122 and is formed in white to prevent discharge light from being transmitted to the rear substrate.

Screen printing is mainly used for forming the lower dielectric layer 124. However, the lower dielectric layer 124 may be formed by various coating methods such as a green sheet laminate method, a slot coater method, and a roll coater method.

The partition wall 121 can be formed by a screen printing method, a sand blast method, a lift-off method, a photosensitive paste method, a direct etching method, or the like.

In addition, a fluorescent film 123 is formed on the surfaces of the lower dielectric layer 124 and the partition wall 121.

Meanwhile, the fluorescent film 123 may be formed of the phosphor paste according to the present invention. The phosphor paste according to the present invention comprises a phosphor powder, a binder, magnesium oxide (MgO) powder, a first solvent and a second solvent, in particular the first solvent is N-methyl-2-pyrrolidone (N-methyl-2 -pyrrolidone (NMP) and the second solvent by using dipropylene glycol n-butyl ether (DPnB) to suppress the viscosity rise of the phosphor paste, ensuring the uniformity of the fluorescent film 123 You can do it.

The partition wall 121 has a vertical partition wall 121a and a horizontal partition wall 121b formed in a closed shape, and physically distinguishes the discharge cells, and prevents ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells.

While the preferred embodiments of the present invention have been shown and described, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention, without departing from the spirit of the invention as claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 is a diagram illustrating a structure of a PDP including a phosphor film formed of a phosphor paste according to an embodiment of the present invention.

Claims (9)

Phosphor powder, binder, magnesium oxide (MgO) powder, a first solvent and a second solvent, The first solvent is N-methyl-2-pyrrolidone (NMP), and the second solvent is Dipropylene Glycol n-butyl Ether (DPnB). Phosphor paste. The method of claim 1, 30 to 50 wt% of the phosphor powder, 5 to 10 wt% of the binder, 1 to 10 wt% of the magnesium oxide (MgO) powder, 9 to 45 wt% of the first solvent, and 15 of the second solvent. Phosphor paste containing from 51 wt%. The method of claim 1, Particle diameter of the phosphor powder is 0.2 to 5㎛ phosphor paste. According to claim 1, The binder is a cellulose resin phosphor paste. The method of claim 1, The phosphor powder is (Y, Gd, Eu) BO ₃ And αFe ₂ O ₃ . The method of claim 1, The phosphor powder is Zn ₂ SiO ₄ : Mn ₂ ⁺ , Al ₂ O ₃ And YBO _3: phosphor paste containing a Tb ₃ ^+. The method of claim 1, The phosphor powder is (Ba, Sr, Eu) MgAl ₁₀ O ₁₇ And CoAl ₂ O ₄ . The method of claim 1, The size of the magnesium oxide (MgO) powder is a phosphor paste of 2nm to 10㎛. A plasma display panel comprising a fluorescent film formed from the phosphor paste of any one of claims 1 to 8.

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