JP2001226669A - Paste composition of fluorescent substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paste composition of fluorescent substance excellent in dispersibility of the fluorescent substance, printability of the paste and low temperature burning property. SOLUTION: This paste composition of fluorescent substance is obtained by dispersing the fluorescent substance in a resin solution obtained by dissolving a polyalkylene carbonate in an organic solvent having no aromatic ring and having a solubility parameter (Sp value) of 8.0-10.0 and surface tension of 25-40 mN/m.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor paste composition for a flat panel display (FPD), and more particularly to a phosphor paste which is excellent in dispersibility of a phosphor substance, printability of a paste, and low-temperature firing property. The composition is proposed.

[0002]

2. Description of the Related Art Generally, as a phosphor paste composition for FPD, a paste composition in which a phosphor substance is dispersed in a binder resin such as a cellulose resin is widely known. Such a phosphor paste composition is applied and printed in a desired pattern on a glass substrate by a screen printing method, and then the binder resin component is calcined and removed in air at a temperature of about 500 ° C. to form a phosphor film and Become.

However, in a paste composition using a binder resin such as a cellulosic resin, a fired residue of a resin component is apt to remain in the obtained phosphor film, and this residue is generated when the phosphor film surface is illuminated. There are practical problems such as black spots, which adversely affect the life of the display.

On the other hand, there has been proposed a phosphor paste composition using an oil-soluble alkyd resin or phenol resin as a binder resin having excellent firing properties. However, in such a phosphor paste composition, the affinity between the intrinsically hydrophilic phosphor substance and the binder resin is insufficient, and a phosphor paste having good castability in which the phosphor substance is uniformly finely dispersed is used. Difficult to get. As a result, when a phosphor film is manufactured using such a phosphor paste in which the phosphor substance is in a poorly dispersed state, the printed phosphor film lacks leveling properties, and the presence of the phosphor material in the film is not sufficient. There is a problem that an undesired portion (pinhole) is generated and the film thickness tends to be uneven.

On the other hand, in order to improve the miscibility between the phosphor substance and the binder resin, the phosphor paste composition has a highly ionic functional group which enhances the affinity with the phosphor substance. There is a method of adding an additive (for example, a compound having a phosphate group or the like). However, such an improvement in the miscibility causes a disadvantage that the baking property of the phosphor paste composition is reduced.

As described above, a phosphor paste composition using a binder resin having excellent miscibility with a phosphor substance and excellent sintering properties, particularly, recently, a decrease in emission luminance due to thermal degradation of the phosphor in a sintering step. From the viewpoint of preventing the occurrence of such a problem, there is a demand for providing a phosphor paste composition using a binder resin which can be fired at a low temperature even in a low oxygen concentration atmosphere and has excellent low-temperature decomposability.

Further, in forming the pattern of the phosphor film by the screen printing method, in order to accurately print such a pattern, it is necessary to not only improve the dispersibility of the phosphor substance but also level the phosphor film to be formed. At the same time as improving the operability, there is a need for a phosphor paste composition with high operability that can be accurately printed on a desired phosphor film size, and the provision of a phosphor paste composition with good so-called thixotropic properties has been demanded. I have.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a main object of the present invention is to provide a fluorescent material which is excellent in dispersibility of a fluorescent substance, printability of a paste, and low-temperature firing property. It is to provide a body paste composition.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies for realizing the above object, and as a result, focused on polyalkylene carbonate as a binder resin excellent in both printability and low-temperature sinterability, using a specific solvent. The inventors have found that a phosphor paste composition capable of achieving the object can be obtained by dispersing a phosphor substance in a resin solution in which a polyalkylene carbonate is dissolved, and have completed the present invention.

That is, the phosphor paste composition of the present invention is prepared by using an organic solvent having no aromatic ring and having a solubility parameter (Sp value) of 8.0 to 10.0 and a surface tension of 25 to 40 mN / m. A phosphor material is dispersed in a resin solution in which a resin containing polyalkylene carbonate as a main component is dissolved. In addition, as the resin containing the polyalkylene carbonate as a main component, a resin containing a resin having a resin skeleton represented by the following chemical formula can be suitably used.

Embedded image In the formula, R1 and R2 represent a hydrogen atom, a methyl group, or an ethyl group, m is an integer of 3 to 400, and n is 40 to 500.
Represents an integer of 0, and a molar ratio of m: n = (1 to 15): 10
0 is shown.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphor paste composition of the present invention is prepared by using an organic solvent having a solubility parameter (Sp value) of 8.0 to 10.0 and a surface tension of 25 to 40 mN / m using a polyalkylene carbonate. Since the resin containing as a main component is dissolved, the dispersibility of the phosphor substance is good, and a suitable leveling property and printability are exhibited. As a result, according to the phosphor paste composition of the present invention, printing can be performed with excellent resolution without causing a problem such as bleeding, particularly in pattern formation of a phosphor film by a screen printing method.
Moreover, the phosphor paste composition of the present invention uses a polyalkylene carbonate having excellent low-temperature baking properties as a binder resin, and furthermore, the resin is dissolved in an organic solvent having no aromatic ring. It has excellent calcination decomposability even under low temperature conditions and low oxygen atmosphere. as a result,
According to the phosphor paste composition of the present invention, low-temperature baking can be performed even in a low oxygen concentration atmosphere.

Hereinafter, the phosphor paste composition of the present invention will be described in detail. First, the polyalkylene carbonate constituting the composition of the present invention has a high oxygen atom content in the resin skeleton, and has an appropriate polar group such as a ketone group and a short side chain in the resin structure, so that the paste Are excellent in a well-balanced manner in printability, sinterability and dispersibility of inorganic powder, and in particular, are characterized by good sintering decomposability even in a low oxygen atmosphere. Such a feature is suitable as a binder resin for a phosphor paste in which there is a concern about deterioration in characteristics in a firing step under the atmosphere.

Examples of such a polyalkylene carbonate include polyethylene carbonate, polypropylene carbonate, polybutylene carbonate and the like. In particular, polypropylene carbonate is effective in that the paste composition has excellent printability and firing property.

[0014] As the binder resin in the composition of the present invention, other resin components can be blended as long as the resin contains polyalkylene carbonate as a main component. For example, a mixed system or copolymer of polyalkylene carbonates such as polyethylene carbonate and polypropylene carbonate, a mixed system with other resin systems, or a copolymer can be used as long as the purpose is not impaired. Among these, in particular, a resin having a resin skeleton represented by the following chemical formula (eg, a copolymer of propylene carbonate and propylene glycol) can impart flexibility without reducing the oxygen atom content in the resin skeleton. Is preferred.

Embedded image In the formula, R1 and R2 represent a hydrogen atom, a methyl group, or an ethyl group, m is an integer of 3 to 400, and n is 40 to 500.
Represents an integer of 0, and a molar ratio of m: n = (1 to 15): 10
0 is shown.

Next, the organic solvent constituting the composition of the present invention has a solubility parameter (Sp value) of 8.0-1.
An organic solvent having no aromatic ring and having a surface tension of 25 to 40 mN / m at 0.0 is used. By using such a solvent, it is possible to obtain a well-balanced phosphor paste composition in which the dispersibility of the phosphor substance, the printability during screen printing, and the burnability of the paste are all excellent. Here, the Sp value and the surface tension value are set in the above ranges because
If the ratio is outside the above range, the solubility of the resin and the wettability of the paste with the base material change, and as a result, the printability and the dispersibility are impaired. On the other hand, when using a solvent having an aromatic ring,
This is because the low-temperature sinterability under a low oxygen atmosphere, which is required particularly for sintering the phosphor paste, is impaired.

The organic solvent may be any organic solvent which does not have an aromatic ring which satisfies the above physical properties, and is not limited. For example, ketones such as methyl ethyl ketone; cellosolve, methyl cellosolve, carbitol, methyl carbitol,
Glycol ethers such as butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate; Acetates such as butyl carbitol acetate, propylene glycol monomethyl ether acetate and dipropylene glycol monomethyl ether acetate; known and common organic solvents such as aliphatic hydrocarbons such as octane and decane can be used. These organic solvents
They can be used alone or in combination of two or more.

The use of dialkylene glycol monoalkyl ether acetate is particularly advantageous in that a phosphor paste having excellent dispersibility of the phosphor substance, printability during screen printing, and combustibility of the paste can be stably obtained. Is preferred. Examples of the alkylene glycol monoalkyl ether acetate include diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, and the like. Is mentioned.

Next, the fluorescent substance constituting the composition of the present invention
The quality is known as a phosphor material for displays.
Blue phosphor material, red phosphor material, green fluorescence
A body substance or the like is used. Examples of blue phosphor materials include
For example, Y_TwoSiO_Five: Ce-based, CaWO_Four: Pb system, Ba
MgAl₁₄O_{twenty three}: Eu-based, BaMgAl₁₆O₂₇: Eu
System, BaMg_TwoAl_{1 Four}O_{twenty three}: Eu-based, BaMg_TwoAl₁₄O
₂₇: Eu type and ZnS: (Ag, Cd) type are used.
It is. As a red phosphor substance, for example, Y_TwoO_Three: Eu
System, Y_TwoSiO_Five: Eu system, Y _ThreeAl_FiveO₁₂: Eu-based, Zn
_Three(PO_Four)_Two: Mn-based, YBO_Three: Eu system, (Y, Gd)
BO_Three: Eu system, GdBO_Three: Eu-based, ScBO_Three: Eu
System, LuBO_Three: Eu type is used. Green fluorescent
As a body substance, for example, Zn_TwoSiO_Four: Mn-based, Ba
Al₁₂O₁₉: Mn-based, SrAl₁₃O₁₉: Mn-based, CaA
l₁₂O₁₉: Mn-based, YBO_Three: Tb-based, BaMgAl₁₄
O_{twenty three}: Mn-based, LuBO_Three: Tb system, GdBO_Three: Tb
System, ScBO_Three: Tb-based, Sr6Si_ThreeO_ThreeCl_Four: Eu type
Is used. In addition, ZnO: Zn-based, Zn
S: (Cu, Al) -based, ZnS: Ag-based, Y_TwoO_TwoS: E
u-based, ZnS: Zn-based, (Y, Cd) BO_Three: Eu type,
BaMgAl₁₂O_{twenty three}: Eu-based materials can also be used
You.

The phosphor material is preferably in the form of a fine powder, and has an average particle size of 0.01 to
It is about 100 μm, more preferably about 0.1 to 10 μm.

In such a phosphor paste composition of the present invention, the proportions of the constituting phosphor substance, polyalkylene carbonate and organic solvent can be appropriately determined according to the intended use or printing method. For example, as a paste composition used for forming a phosphor film by a screen printing method for FPD, a resin solution obtained by dissolving a resin containing polyalkylene carbonate as a main component using an organic solvent, and a phosphor material are prepared by mass ratio. It is preferable to mix at a ratio of 50 to 80:50 to 20.

Further, the phosphor paste composition of the present invention comprises:
The viscosity can be adjusted appropriately according to the printing method.
For example, as a paste composition for screen printing,
The range is 5 to 300 Pa · s poise at 25 ° C., preferably 10 to 200 Pa · s. The reason is 5P
If it is less than a · s, the fluidity of the phosphor paste composition is too large, and the printing workability deteriorates. Is likely to occur, which is not preferable in terms of reproducibility of the shadow mask pattern. On the other hand, 200 Pa
If the value exceeds s, the fluidity of the phosphor paste composition is too low, and the surface of the phosphor film formed with the phosphor paste is likely to have irregularities, which is not preferable.

In the phosphor paste composition of the present invention, a known plasticizer or a known plasticizer may be used as long as the purpose is not impaired.
Various additives such as a dispersion stabilizer, a leveling agent, and a thixotropic agent can be added.

[0023]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but it goes without saying that the present invention is not limited to the following Examples. In the following, “parts” and “%” are all based on mass unless otherwise specified.

Example 1 (1) 100 parts of polypropylene carbonate was added to diethylene glycol monoethyl ether acetate (Sp
(Value: 9.2, surface tension: 31.1 mN / m).
% Resin solution was prepared. (2) in the resin solution 65 parts prepared in (1), phosphor powder by kneading _{(BaMg 2 Al 1 4 O 23} :: blue fluorescent substance represented by the Eu average particle size 7.0 .mu.m) 35 parts The phosphor was dispersed, and diethylene glycol monoethyl ether acetate was further added to obtain a phosphor paste composition whose viscosity was adjusted to 15 Pa · s.

Comparative Example 1 A phosphor paste composition was prepared in the same manner as in Example 1 except that o-xylene (Sp value: 9.0, surface tension: 30.0 mN / m) was used as an organic solvent. I got

Comparative Example 2 n-butanol as organic solvent (Sp value: 11.4, surface tension: 23.8 mN / m)
Except for using, a phosphor paste composition was obtained in the same manner as in Example 1.

Comparative Example 3 A phosphor paste composition was obtained in the same manner as in Example 1 except that an acrylic resin was used as the binder resin.

Comparative Example 4 A phosphor paste composition was obtained in the same manner as in Example 1 except that ethyl cellulose was used as the binder resin.

With respect to the phosphor paste compositions obtained in Examples and Comparative Examples, the dispersibility of the phosphor substance, the printability of the paste, and the baking property were evaluated. The evaluation method is as follows. [Printability] The phosphor paste whose viscosity was adjusted to 15 Pa · s was printed on a 150 μm width stripe pattern with a # 300 mesh screen, and the blur width of the phosphor film pattern was measured with an optical microscope of 50 to 400 times, Printability was evaluated. The evaluation criteria are as follows. The viscosity is a value measured at 25 ° C. with an E-type viscometer (manufactured by Tokyo Keiki Co., Ltd.). ○: less than ± 10 μm △: ± 10 μm or more and less than 20 μm ×: ± 20 μm or more [Dispersibility] As an index reflecting the dispersibility of the phosphor substance,
The concealing property and the smoothness of the phosphor film pattern prepared in the above evaluation of printability were examined. <Hiding property>: The presence or absence of pinholes on the phosphor film surface was examined with an optical microscope (50 to 400 times) using transmitted light and reflected light. ：: No pinhole ×: Pinhole present <Smoothness>: The cross section of the phosphor film was observed with an electron microscope (500 ×), and the unevenness of the phosphor film surface was examined. ：: Less unevenness (5 μm or less), no trace of screen mesh Δ: Slightly more uneven, ×: More unevenness, trace of screen mesh [Firing property] 10 mg of the phosphor paste composition obtained in Examples and Comparative Examples was used. A 20 μm-thick pattern is applied and dried on a glass substrate by a screen printing method, and the phosphor paste pattern is formed with an oxygen partial pressure of about 1 to 15% by volume.
Normal temperature → 430 ℃ under nitrogen gas atmosphere adjusted to
(The temperature was raised at a rate of 15 ° C./min.), And after baking at 430 ° C. × 1 hour, the presence or absence of a firing residue was observed. ○: No residue ×: Residue

Table 1 shows the results of the evaluation. As is clear from the results shown in this table, according to the phosphor paste composition of the present invention, printing can be performed with almost no bleeding, and the resulting paste pattern has no pinholes and complete concealment. It was confirmed that the paste pattern had a smooth surface as shown, and that the paste pattern could be fired without firing residue even at a low temperature and in a low oxygen atmosphere.

[0031]

[Table 1]

[0032]

As described above, according to the phosphor paste composition of the present invention, the phosphor paste having excellent dispersibility of the phosphor substance and printability of the paste, and excellent sinterability even in a low temperature and low oxygen atmosphere. The composition can be provided stably, and the effect is extremely large.

Claims (2)

[Claims] 1. A solubility parameter (Sp value) of 8.0 to 1
A fluorescent substance is dispersed in a resin solution in which a resin containing polyalkylene carbonate as a main component is dissolved using an organic solvent having an aromatic ring having a surface tension of 25 to 40 mN / m and having a surface tension of 0.0. A phosphor paste composition comprising: 2. The phosphor paste composition according to claim 1, wherein the resin containing polyalkylene carbonate as a main component includes a resin having a resin skeleton represented by the following chemical formula. Embedded image In the formula, R1 and R2 represent a hydrogen atom, a methyl group, or an ethyl group, m is an integer of 3 to 400, and n is 40 to 500.
Represents an integer of 0, and a molar ratio of m: n = (1 to 15): 10
0 is shown.