JP2003226868A - Fluorescent paste and method for producing display panel member by using the paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fluorescent paste resistant to the lowering in the luminance of its fluorescent material. <P>SOLUTION: The fluorescent paste contains powder of the fluorescent material, a binder resin and an organic solvent. The water absorption rate of the paste is ≤5,000 ppm/hr and the water solubility of the organic solvent is ≤7 at 25°C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor paste containing phosphor powder, a binder resin and an organic solvent, and a method for manufacturing a display panel member such as a plasma display and a plasma addressed liquid crystal display using the phosphor paste.

[0002]

2. Description of the Related Art Plasma display panels (hereinafter referred to as "P"
"DP") is capable of high-speed display as compared with a liquid crystal panel and is easy to be upsized, and therefore has permeated into fields such as office automation equipment and publicity display devices. Furthermore, there are great expectations for progress in the field of high-definition television. Along with such expanding applications, color PDPs having a large number of fine display cells have been receiving attention.

A PDP causes a plasma discharge between electrodes in a discharge space provided between a front glass substrate and a rear glass substrate, and discharges ultraviolet rays generated from a gas enclosed in the discharge space. The display is performed by applying the fluorescent substance inside.

As a method of forming this phosphor, a screen printing method using a phosphor paste composed of phosphor powder, a binder resin and an organic solvent, an ink jet method, a method of ejecting the phosphor paste from a die, a phosphor A photo film method and a photo paste method using a photosensitive phosphor paste containing a photosensitive organic component in the paste are known.

The phosphor paste and the photosensitive phosphor paste used for forming these phosphors are desired to exhibit sufficient brightness when they are made to emit light as a PDP.

However, if there is water in the phosphor paste or the photosensitive phosphor paste, there is a problem that the components on the surface of the phosphor powder are eluted by the water and the brightness of the phosphor is lowered. In addition, there is a problem that the brightness of the phosphor changes depending on the time for which the paste is left, and the panel characteristics become non-uniform depending on the panel manufacturing lot.

[0007]

Therefore, in view of the above-mentioned problems of the prior art, the present invention provides a phosphor paste capable of forming a stable phosphor without lowering the brightness of the phosphor. To aim.

Another object of the present invention is to provide a method for manufacturing a stable and high-quality member for a plasma display panel, which uses such a phosphor paste.

[0009]

In order to solve the above-mentioned problems, the present invention is a phosphor paste containing phosphor powder, a binder resin and an organic solvent, wherein the water absorption rate of the paste is 5,000 ppm / hour or less. And the solubility of the organic solvent in water at 25 ° C. is 7 or less.

Further, the present invention is a method of manufacturing a member for a display panel, which comprises a step of applying a phosphor paste onto a substrate having at least electrodes, dielectrics and barrier ribs and drying the paste. A method of manufacturing a member for a display panel, which is characterized in that it is used.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphor paste of the present invention is a phosphor paste which essentially contains phosphor powder, a binder resin and an organic solvent and has a water absorption rate of 5,000 ppm / hour or less. The water absorption rate is preferably 3,000 ppm / hour. When the water absorption speed of the phosphor paste is within this range, an excellent phosphor paste that does not reduce the brightness of the phosphor can be obtained. Also, even if the paste is left for a long time, the brightness of the phosphor does not change, and the panel characteristics become uniform,
It is possible to obtain a stable and high-quality member for a plasma display panel.

The water absorption rate of the phosphor paste is obtained from the water absorption rate per unit time. A water content meter can be used to measure the water absorption, but in the present invention, Hiranuma Sangyo Co., Ltd.
Trace moisture analyzer AQ-7 and moisture vaporization accessory EV
Using -6, the measurement was carried out by a 200 ° C. heating vaporization method (a method of heating a sample at 200 ° C. to vaporize water, and introducing this into a titration cell with dry nitrogen gas for measurement). When directly measuring with a trace moisture analyzer, the phosphor powder is dispersed in the electrolytic solution, the background after measurement becomes unstable, and there are difficulties in sampling. It is preferable because it can be obtained. The conditions for leaving to determine the water absorption rate are
The temperature is 23 ± 2 ° C. and the humidity is 50 ± 5%.

As the phosphor powder used in the present invention,
For example, for red, Y ₂ O ₃ : Eu, YVO ₄ : Eu,
(Y, Gd) BO ₃ : Eu, Y ₂ O ₃ S: Eu, γ-Zn _{3
(PO 4) 2: Mn,} (ZnCd) S: such as Ag + In ₂ O ₃ and the like. In green, Zn ₂ GeO ₂ : M, BaA
l ₁₂ O ₁₉ : Mn, Zn ₂ SiO ₄ : Mn, LaPO ₄ : T
b, ZnS: Cu, Al, ZnS: Au, Cu, Al,
(ZnCd) S: Cu, Al, Zn ₂ SiO ₄ : Mn, A
s, 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
And so on. In blue, Sr ₅ (PO ₄ ) ₃ Cl:
Eu, BaMgAl ₁₄ O ₂₃ : Eu, BaMgAl
₁₆ O ₂₇ : Eu, BaMg ₂ Al ₁₄ O ₂₄ : Eu, ZnS:
Examples thereof include Ag + red pigment and Y ₂ SiO ₃ : Ce.

Further, thulium (Tm), terbium (T
b) and at least one element selected from the group consisting of europium (Eu) and tantalic acid substituted with at least one base-constituting rare earth element selected from yttrium (Y), gadolinium (Gd) and lutetium (Lu). Rare earth phosphors can also be used. Preferably,
The rare earth tantalate phosphor has the composition formula Y _1-X Eu _x TaO.
_The europium-activated yttrium tantalate phosphor represented by the formula ₄ (wherein X is approximately 0.005 to 0.1). For the red phosphor, europium-activated yttrium tantalate is preferably used, and for the green phosphor,
The rare earth tantalate phosphor has the composition formula Y _1-X Tb _x TaO.
_The terbium-activated yttrium tantalate represented by the formula ₄ (wherein X is approximately 0.001 to 0.2) is preferably used. The blue phosphor is a thulium-activated tantalum acid represented by a rare earth tantalate phosphor Y _1-X Tm _X TaO ₄ (where X is approximately 0.001 to 0.2). The phosphor powder used in the phosphor paste of the present invention in which yttrium is preferably used has an area average diameter (Ds) of 1.0 to 2.5 μm and a center diameter (Dv) of volume-based distribution of 1.8 to 4 0.5 μm, Ds / Dv is 1.2 to
It is preferably 2.5, more preferably Ds
Is 1.2 to 2.3 μm, Dv is 2.0 to 4.2 μm, D
s / Dv is within the range of 1.3 to 2.3. Ds, Dv
It is preferable that Ds / Dv is within this range because the filterability of the paste can be improved.

Specific examples of the binder resin used in the present invention include polyamides, polyethers, copolymers of ethylene oxide and propylene oxide, polyacrylamides and various acrylic polymers (eg sodium polyacrylate, poly (lower alkyl acrylate). , Poly-lower alkyl methacrylates and various copolymers and multi-polymers of lower alkyl acrylates and methacrylates), ethyl cellulose and the like.

The binder resin used in the present invention preferably has a water absorption of 2% or less, more preferably 1.5% or less. For the water absorption rate, the above-mentioned measuring method can be used. If the water absorption rate of the binder resin exceeds 2%, the water absorption rate of the paste will be increased.

The organic solvent used in the present invention must have a solubility in water at 25 ° C. of 7 or less. It is preferably 5 or less. When the solubility in water is 7 or less, the water absorption speed of the paste can be slowed.

The solubility in water is determined by mixing an organic solvent and water to make it supersaturated and measuring the water content in the organic solvent. The solubility value is shown by how much water is dissolved in 100 g of the organic solvent.

In the present invention, 2,2,4 is used as the organic solvent.
-Trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, ethylene glycol mono-2
It is preferably at least one selected from ethylhexyl ether and diethylene glycol mono-2-ethylhexyl ether. 2,2,4-trimethyl-
1,3-pentanediol monoisobutyrate, 2,
Phosphor paste by using at least one organic solvent selected from 2,4-trimethyl-1,3-pentanediol diisobutyrate, ethylene glycol mono-2-ethylhexyl ether and diethylene glycol mono-2-ethylhexyl ether The water absorption rate of 5,000 ppm / hour or less can be achieved, and an excellent phosphor paste with no decrease in the brightness of the phosphor can be obtained.
Further, even if the paste is left for a long time, the brightness of the phosphor does not change, the panel characteristics become uniform, and a stable and high-quality member for a plasma display panel can be obtained.

In the present invention, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate,
100% by weight of an organic solvent which is at least one selected from 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, ethylene glycol mono-2-ethylhexyl ether, and diethylene glycol mono-2-ethylhexyl ether It is preferable that the amount is 85 parts by weight or more in 100 parts by weight, but other organic solvents can be appropriately added within the range of not more than 20 parts by weight in 100 parts by weight of the organic solvent for the purpose of adjusting the drying. Specifically, diethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, 2-ethyl-1,3-hexanediol, terpineol, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether. Examples thereof include acetate, benzyl alcohol, propylene carbonate and the like.

2,2,4-Trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol At least one organic solvent selected from mono-2-ethylhexyl ether is preferably added in an amount of 10 to 500 parts by weight, more preferably 20 to 3 parts by weight, relative to 100 parts by weight of the phosphor paste.
It is in the range of 00 parts by weight. If it is less than 10 parts by weight, the viscosity becomes high and it becomes difficult to uniformly mix or apply it, while if it exceeds 500 parts by weight, the viscosity is lowered and it is not suitable for practical use.

The above phosphor powder, binder resin and organic solvent are mixed, dispersed and kneaded in a desired ratio to prepare a phosphor paste.

Other constituents of the phosphor paste of the present invention include antioxidants, defoamers, dispersants, etc. Among these, addition of a dispersant is preferable.
This is effective because the dispersibility of the phosphor paste can be improved.

As the dispersant, specifically, polyoxyalkylene alkyl ether, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan acid ester, polyoxyalkylene alkyl ether acetic acid, fatty acid alkylolamide, polyoxyethylene polyoxypropylene. A block polymer or the like can be given as an example. In addition, fatty acid soap such as fatty acid sodium soap, alkyl sulfate, sodium dioctyl sulfosuccinate, ethoxy phosphate, etc.
Since there is a possibility that the brightness may decrease, it is necessary to pay attention to the addition amount when using, and 0.1 to 10w in the phosphor paste.
t% is preferably contained.

Further, particularly when the phosphor paste of the present invention is used as a photosensitive phosphor paste, a photosensitive component such as a photosensitive monomer, a photosensitive oligomer or a photosensitive polymer, a photopolymerization initiator, a sensitizer, Additive components such as an antioxidant, an ultraviolet absorber and a polymerization inhibitor can be added. As the photosensitive monomer used at this time, a compound having an active carbon-carbon double bond is often used. As the functional group, a monofunctional or polyfunctional compound having a vinyl group, an allyl group, an acrylate group, a methacrylate group, or an acrylamide group can be applied. The oligomer or polymer is obtained by polymerizing or copolymerizing a component selected from compounds having a carbon-carbon double bond. By copolymerizing an unsaturated acid such as an unsaturated carboxylic acid, the developability in an alkaline aqueous solution after exposure can be improved. Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinylacetic acid, and their acid anhydrides. The acid value (AV) of the polymer or oligomer having an acidic group such as a carboxyl group in the side chain thus obtained is 50 to 180, and further 70
The range of to 140 is preferable. From the viewpoint of photosensitivity, it is preferable to add the photopolymerization initiator in the range of 0.005 to 5% by weight with respect to the phosphor paste.

The phosphor paste of the present invention is prepared by mixing various components so as to have a predetermined composition, and then homogeneously prepared by a dispersing / kneading means such as a three-roller, a homogenizer, or an automatic mortar. The various components are preferably dehydrated by vacuum drying or molecular sieve before preparation.

Next, an example of a method for manufacturing a display panel member will be described. Striped electrodes are formed on the substrate as a writing electrode by a photolithography method using a photosensitive silver paste, and the dielectric paste is applied to the substrate by a screen printing method, and then 500 to 6
Baking at 00 ° C. forms a dielectric layer.

Further, after a pattern is formed on the dielectric layer by a photolithography method using a photosensitive glass paste, the thickness of 500 to
Baking is performed at 600 ° C. for 10 to 60 minutes to form a stripe-shaped partition wall pattern.

The phosphor paste is formed on the partition thus formed. The method of forming the phosphor is not particularly limited, and examples thereof include a screen printing method, a method of ejecting the phosphor paste from the die, and a photosensitive paste method. Among these, a method of ejecting the phosphor paste from the die, a screen. PD with simple printing method and low cost
It is preferable because P can be obtained. After the phosphor paste is applied and dried, the phosphor layer is formed on the side surface and the bottom of the partition wall, for example, by baking at 500 ° C. for 30 minutes.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples. However, the present invention is not limited to this. The concentration (%) in the examples is% by weight. (Materials Used in Examples and Comparative Examples of the Present Invention) (1) Red phosphor powder: (Y, Gd, Eu) BO ₃ (2) Green phosphor powder: (Zn, Mn) ₂ SiO ₂ (3) blue phosphor _{powder: (Ba, Eu) MgAl 10} O 17 (4) binder resin A: ethyl cellulose binder resin B: PMMA (5) an organic solvent a: 2,2,4-trimethyl-1,3
Pentanediol monoisobutyrate organic solvent b: 2,2,4-trimethyl-1,3-pentanediol diisobutyrate organic solvent c: Ethylene glycol mono-2-ethylhexyl ether organic solvent d: Diethylene glycol mono-2-ethylhexyl ether Organic solvent e: ethylene glycol monobutyl ether acetate organic solvent f: diethylene glycol monobutyl ether acetate organic solvent g: diethylene glycol monobutyl ether organic solvent h: triethylene glycol monobutyl ether. (Measurement and evaluation method) (1) Water absorption measuring device: Hiranuma trace amount moisture measuring device AQ-7 Moisture vaporizing device: Hiranuma moisture vaporizing accessory device EV-6 Evolving liquid: Hydranal aquarite RS-A Counter electrode liquid: Hydra NARL AQUALITE CN Measurement conditions: CAL MODE 0 INTERVAL 20 seconds CURRENT FAST S-TIMER 2 minutes Set temperature 200 ° C. Nitrogen flow rate 200 ml / powder.

(2) Luminous Emission Maintenance Ratio by Paste Firing First, the luminous intensity (energy) which is the luminous characteristic of the phosphor.
Was measured. Approximately 600 mg of phosphor powder has a diameter of 24 mm,
The plate was placed in a SUS dish (sample holder) having a depth of 1 mm, and a glass plate was pressed to flatten it. This sample was put into the chamber, and the inside of the chamber was once evacuated to 5 Pa or less by a rotary pump, and then nitrogen gas having a purity of 99.9% or more was flown and left for 30 minutes to replace the inside of the chamber with nitrogen gas. . After that, an excimer light emitting lamp H0012 (irradiation opening: diameter 27 mm) manufactured by Ushio
UV light of 146 nm was irradiated from an excimer light irradiation device with a built-in, at a position 25 cm away from the sample surface at an incident angle of 20 degrees. The emission intensity is measured from 23 cm directly above the sample surface to the instantaneous multi-photometry system MCPD-200 manufactured by Otsuka Electronics Co., Ltd.
It was measured at 0. Next, the emission characteristics after firing the phosphor paste were measured. The phosphor paste was applied onto the glass substrate by screen printing (screen plate: SUS # 200) to a dry thickness of 30 μm, and the coating film was applied at 80 ° C.
In the oven for 30 minutes, then put in the baking oven,
What was baked at 500 ° C. for 15 minutes was scraped off and put in the same sample holder as above, and the measurement was carried out. The paste firing luminescence maintenance rate is I when the integrated value (energy) of the spectrum of the emission intensity of the phosphor powder is Ip and the emission energy Is of the phosphor powder after firing the phosphor paste is I.
It was shown by s / Ip × 100 (%). Further, the phosphor paste was stored in an atmosphere of 23 ° C. and 50 RH% for 500 hours, and then the paste firing luminescence maintenance rate was measured. The change rate of the paste firing luminescence maintenance rate is the initial paste firing luminescence maintenance rate I ₀ , and the paste firing luminescence maintenance rate I after storage for 500 hours.
_{When set to 500} , it is shown by (I ₀ -I ₅₀₀ ).

(3) Luminance characteristic of panel The luminance and chromaticity of the panel are the panel luminance when discharged with a sustaining voltage of 170 V, a frequency of 30 kHz and a pulse width of 3 μm, and the rate of change of the panel luminance when driven for 500 hours. It was measured. The rate of change of the panel brightness is the initial panel brightness L ₀ ,
When the panel brightness after driving for 500 hours is L ₅₀₀ , (L ₀ −
_L500 ).

(Examples 1 to 10 and Comparative Examples 1 to 3) First, 20 g of binder resin, 100 g of any one of various red, green, and blue phosphor powders, and the organic solvent shown in Table 1 were used. Mix, disperse and knead with three rollers,
About 200 g of phosphor paste was obtained. The firing luminescence maintenance rate of the obtained phosphor paste was measured immediately after the paste was prepared (initial stage) and after being stored in an atmosphere of 23 ° C. and 50 RH% for 500 hours. The results are shown in Table 1.

Next, a back plate of an AC (alternating current) type plasma display panel was formed using a glass substrate ("PD-200" manufactured by Asahi Glass Co., Ltd.) having a size of 340 x 260 x 2.8 mm.

Stripe electrodes having a pitch of 140 μm, a line width of 60 μm and a thickness of 4 μm after firing were formed on the substrate as a writing electrode by a photolithography method using a photosensitive silver paste. A dielectric paste was applied to this substrate by a screen printing method and then baked at 550 ° C. to form a dielectric layer having a thickness of 10 μm.

Further, by using the above-mentioned glass paste on the dielectric layer and by patterning by sandblasting through a subtractive mask layer formed by photolithography, after patterning, baking at 570 ° C. for 15 minutes, pitch 140 μm,
A stripe-shaped partition wall pattern having a line width of 20 μm and a height of 100 μm was formed.

The various phosphor pastes shown in Table 1 were applied to the partition thus formed by a method of discharging the phosphor paste from the die. After coating, it was dried and baked (500 ° C., 30 minutes) to form a phosphor layer on the side surface and the bottom portion of the partition wall.

Next, a front plate was manufactured by the following steps. First, ITO is formed on the same glass substrate as the back plate by a sputtering method, resist is applied, and the thickness is 0.1 μm and the line width is 200 μm by exposure / development and etching.
Transparent electrodes were formed. In addition, by photolithography using a photosensitive silver paste made of black silver powder,
After firing, a bus electrode having a thickness of 10 μm was formed. The electrodes were manufactured with a pitch of 140 μm and a line width of 60 μm.

Further, 20 μm of transparent dielectric paste was applied on the front plate on which the electrodes were formed, and the paste was baked by holding it at 430 ° C. for 20 minutes. Next, an MgO film having a thickness of 0.5 μm was formed by using an electron beam vapor deposition machine so as to uniformly cover the formed transparent electrode, black electrode and dielectric layer to complete the front plate.

The obtained front glass substrate was bonded and sealed to the back glass substrate described above, and then a discharge gas was sealed in and a drive circuit was joined to the plasma display (PD).
P) was prepared. This PDP has a sustaining voltage of 170 V,
The panel brightness at a frequency of 30 kHz and the panel brightness at a driving time of 500 hours were measured. The results are shown in Table 1.

Table 1 shows Examples 1 to 10 and Comparative Examples 1 to 1.
The types of binder resin used for the phosphor paste of No. 3, the type of organic solvent, the solubility of the organic solvent in water, the paste firing luminescence maintenance rate measured using the paste, and the panel brightness are shown together.

[0042]

[Table 1]

The water absorption rate of the pastes obtained in Examples 1 to 10 was 5000 ppm / hour or less. After the paste was stored for 500 hours in an atmosphere of 23 ° C. and 50 RH%, the rate of change in the luminescence maintenance rate after firing was 0 to −6%. Further, the rate of change in panel brightness was also good at -2 to -6%.

The water absorption rate of the pastes obtained in Comparative Examples 1 to 3 was 5000 ppm / hour or more. The change rate of the luminescence maintenance rate after storage of this paste for 500 hours in an atmosphere of 23 ° C. and 50 RH% was −8 to −17%. In addition, the rate of change in panel brightness was -9 to -12%, which was unsatisfactory.

[0045]

INDUSTRIAL APPLICABILITY The phosphor paste of the present invention is a paste containing phosphor powder, a binder resin and an organic solvent and has a water absorption rate of 5,000 ppm / hour or less. It is possible to provide a phosphor paste capable of forming the above phosphor. The purpose is to provide.

Continued front page    F-term (reference) 4H001 CA01                 5C028 FF06 FF12                 5C040 FA01 GG08 GG09 MA23

Claims (5)

[Claims] 1. A phosphor paste containing phosphor powder, a binder resin and an organic solvent, wherein the water absorption rate of the paste is 5,000 ppm / hour or less and the solubility of the organic solvent in water at 25 ° C. is 7. A phosphor paste characterized by the following: 2. The organic solvent is 2,2,4-trimethyl-1,
3-pentanediol monoisobutyrate, 2,2,4
-Trimethyl-1,3-pentanediol diisobutyrate, at least one selected from ethylene glycol mono-2-ethylhexyl ether and diethylene glycol mono-2-ethylhexyl ether. paste. 3. 2,2,4-Trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, ethylene glycol mono-2-ethylhexyl ether. The phosphor paste according to claim 1 or 2, wherein at least one selected from diethylene glycol mono-2-ethylhexyl ether is contained in an amount of 85% by weight or more in 100% by weight of the organic solvent. 4. The phosphor paste according to claim 1, which is used for forming a phosphor of a display. 5. A method of manufacturing a member for a display panel, which comprises a step of applying a phosphor paste on a substrate having at least electrodes and partition walls formed thereon and drying the phosphor paste, wherein the phosphor paste is any one of claims 1 to 3. A method for manufacturing a member for a display panel, which is the phosphor paste described in 1.