JP2000204362A - Pasty composition of fluorescent substances - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition hardly causing change in viscosity, especially decrease of viscosity with time on storage, usable for formation of fluorescent film for flat panel display by adding an antioxidant to a specific fluorescent substance paste composition. SOLUTION: A phenolic antioxidant such as 2,6-di-tert-butyl-p-cresol, preferably substantially causing no thermal reduction at >=350 deg.C, and preferably in an amount of 0.05-10 pts.wt., more preferably 0.3-3 pts.wt. based on 100 pts.wt. binder resin is added to a fluorescent substance paste composition for forming a fluorescent film, obtained by allowing a fluorescent substance to be dispersed in a solvent containing the binder resin, preferably an ethylcellulose resin or the like to provide the objective composition usable for forming the fluorescent film for a field emission display(FED), a plasma display panel(PDP) or the like by using a screen printing method or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a field emission display (FED) and a plasma display panel (PDP) using a printing method such as a screen printing method.
The present invention relates to a phosphor paste composition used for forming a phosphor film of a flat panel display (FPD).

[0002]

2. Description of the Related Art A fluorescent film for an FPD such as an FED or a PDP is mainly kneaded with an organic solvent together with a binder resin, and the phosphor is dispersed in an organic solvent containing the binder resin to form a paste. By doing so, a phosphor paste composition is prepared, and is printed in a predetermined pattern on a transparent substrate by a printing method such as a screen printing method.

[0003] The phosphor paste composition used for such an application is required for obtaining a phosphor film having good performance.
Also, from the viewpoint of workability, it is important to adjust the viscosity when printing and coating on the substrate. The viscosity of this phosphor paste composition depends on the type of phosphor used therein and the phosphor paste composition. Depending on the temperature at the time of manufacture of the product, the viscosity decreases over time, and even if it is adjusted to a viscosity that is easy to apply at the time of manufacture, the viscosity at the time of manufacture changes during storage, so the difference in storage time The thickness of the printed film fluctuates, or the printing width is widened.However, the viscosity of the phosphor paste composition whose viscosity once decreased during storage is difficult to re-adjust, so that there is a problem that it cannot be used.
The improvement was desired.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a phosphor paste composition for forming a phosphor film, which is less likely to undergo a change in viscosity over time during storage, especially a decrease in viscosity.

[0005]

Means for Solving the Problems The present inventors have intensively studied the composition of the phosphor paste composition in order to solve the above problems of the phosphor paste composition for forming a phosphor film by a printing method. As a result, it has been found that when a certain kind of antioxidant is contained in the phosphor paste composition, the viscosity of the paste composition does not easily change over time, and the above object is achieved, and the present invention has been achieved. Was.

That is, the present invention is as follows. (1) A phosphor paste composition for forming a phosphor film obtained by dispersing a phosphor in a solvent containing a binder resin, wherein the composition contains an antioxidant. . (2) The phosphor paste composition as described in (1) above, wherein the antioxidant is a compound having substantially no heat loss at 350 ° C. or higher. (3) The phosphor paste composition as described in (1) or (2) above, wherein the antioxidant is a phenolic antioxidant.

(4) The phenolic antioxidant is 2,
The phosphor paste composition according to the above (3), which is 6-di-tert-butyl-p-cresol. (5) The content of the antioxidant is 100% of the binder resin.
The phosphor paste composition according to any one of (1) to (4), wherein the amount is 0.05 to 10 parts by weight with respect to parts by weight. (6) The content of the antioxidant is 100% of the binder resin.
The phosphor paste composition according to the above (5), wherein the amount is 0.3 to 3 parts by weight with respect to parts by weight. (7) The phosphor paste composition according to any one of (1) to (6), wherein the binder resin is an ethylcellulose resin.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In order to produce the phosphor paste composition of the present invention, in addition to the phosphor and the binder resin, a mixture obtained by adding a certain antioxidant thereto is kneaded, and the mixture is mixed in an organic solvent containing the binder resin. The phosphor is manufactured in the same manner as the conventional phosphor paste composition except that the phosphor and the antioxidant are uniformly dispersed.

As the phosphor used in the phosphor paste composition of the present invention, any phosphor used in conventional phosphor paste compositions can be used.
There is no particular limitation on the phosphor composition used, and it is appropriately selected according to the excitation source of the display that excites the phosphor film formed using the phosphor composition.

For example, when the phosphor paste composition of the present invention is used for forming a fluorescent film such as a cathode ray tube (CRT) or an FED, the fluorescent film is irradiated with an electron beam to emit light. Activated yttrium oxysulfide phosphor (Y ₂ O ₂ S: Eu), europium activated yttrium oxide phosphor (Y ₂ O ₃ : Eu), copper and aluminum activated zinc sulfide phosphor (ZnS: Cu, Al), Terbium-activated yttrium aluminate phosphor (Y ₃ Al ₅
O ₁₂ : Tb), silver-activated zinc sulfide phosphor (ZnS: A)
g), silver and aluminum activated zinc sulfide phosphor (Zn
A phosphor for electron beam that emits light with high efficiency under the excitation of an electron beam such as S: Ag, Al) is used. When the phosphor is used for forming a phosphor film such as PDP, the phosphor film is irradiated with ultraviolet rays to emit light. Therefore, Y ₂ O ₂ S: Eu, europium-activated yttrium borate phosphor (YBO ₃ : E
u), europium-activated yttrium / gadolinium borate phosphor {(Y, Gd) BO ₃ : Eu)}, manganese-activated zinc silicate phosphor (Zn ₂ SiO ₄ : Mn), manganese-activated barium magnesium aluminate fluorescence Body (BaM
gAl ₁₄ O ₂₃ : Mn) divalent europium activated barium magnesium aluminate phosphor (BaMg ₂ Al)
₁₄ O ₂₄ : Eu ²⁺ ), and other ultraviolet and vacuum ultraviolet phosphors that emit light with high luminance under excitation of ultraviolet light or vacuum ultraviolet light are used.

The degree of change in the viscosity of the phosphor paste composition over time varies depending on the type of the phosphor in the phosphor paste composition. The conventional phosphor paste composition as the phosphor paste composition has a large degree of viscosity fluctuation over time, but when these phosphors are used as the phosphor paste composition of the present invention, the phosphor paste composition over time does not The change in viscosity is very small.

The phosphor used in the phosphor paste composition of the present invention has the same or similar body color as the emission color on the surface of each phosphor by using a binder such as an acrylic emulsion or polyvinyl alcohol. It is particularly preferable to use a conventionally known phosphor with a pigment to which a coloring material such as a pigment is applied in advance, since the contrast of an image by the obtained phosphor film can be increased.

In the phosphor paste composition of the present invention,
The binder resin for dispersing the phosphor is not particularly limited as long as it is excellent in dispersibility of the phosphor, but it is necessary to dissolve it uniformly in an organic solvent, and specific binding that can be used. Examples of the agent resin include, for example, methacrylic acid ester polymer, styrene-acrylic acid ester copolymer, polystyrene, polyvinyl butyral, polyvinyl alcohol, ethyl cellulose, etc., but from the flow characteristics of the paste during screen printing, thixotropic Ethyl cellulose having properties is particularly preferred.

In the phosphor paste composition of the present invention, the binder resin is used as an organic solvent for dissolving the binder resin and for easily adjusting the viscosity of the obtained phosphor paste composition. Any solvent can be used as long as it can stably dissolve, but specifically, toluene, aromatic hydrocarbon compounds such as xylene, tetrahydrofuran, ether compounds such as 1,2-butoxyethane, acetone, Ketone compounds such as methyl ethyl ketone, ethyl acetate, butyl acetate, ester compounds such as diethylene glycol monobutyl ether acetate, dioctyl phthalate, isopropyl alcohol, diethylene glycol monobutyl ether, terpineol,
-Alcohol compounds such as phenoxyethanol. In particular, when used for screen printing, it is preferable to use an organic solvent having a boiling point of 170 ° C. or higher.

Further, in the phosphor paste composition of the present invention, it is essential to add an antioxidant, and as the antioxidant which can be used, thio-, phosphorus- and phenol-based organic compounds are prevented from being oxidized. Agents are desirable, and among these, an organic compound having substantially no heat loss at 350 ° C. or higher is recommended. That is, in general, when an organic compound is heated from room temperature and heated up, a weight loss during heating to a certain temperature due to partial decomposition by heat or the like is observed. Is more preferably used.

The antioxidants having such properties are preferably 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis- (4-methyl-6).
-Tert-butylphenol) and phenolic antioxidants such as 4,4'-thiobis- (3-methyl-6-tert-butylphenol) are preferred, and among these, 2,6-di-tert-butyl- is particularly preferable. p-Cresol is encouraged.

By including such an antioxidant in the phosphor paste composition, the storage stability of the phosphor paste over time after its preparation is remarkably improved. When the content of the antioxidant is less than 0.05 part by weight with respect to 100 parts by weight of the binder resin in the phosphor paste composition, the obtained phosphor paste composition has sufficient viscosity stability over time. On the other hand, when the content exceeds 10 parts by weight, when the phosphor film is used, the emission luminance of the phosphor film is reduced.
The content of the antioxidant in the phosphor paste composition is preferably in the range of 0.05 to 10 parts by weight with respect to the binder resin in the phosphor paste composition.
More preferably, it is in the range of 3 to 3 parts by weight.

[0018]

Next, the present invention will be described with reference to examples. (Production of phosphor paste composition) [Example 1] 100 parts by weight of (Y, Gd) BO ₃ : Eu
Phosphor (KX-504A manufactured by Kasei Optonics), 20
Parts by weight of ethyl cellulose (binder resin), 150 parts by weight of butyl carbitol (organic solvent) and 0.2 parts by weight of 2,6-di-tert-butyl-p-cresol (antioxidant; manufactured by Yoshitomi Pharmaceutical Co., Ltd.) A mixed composition composed of Yoshinox BHT) was mixed with a three-roll mill, and adjusted so that the viscosity at a shear rate of 5 (1 / s) was 40,000 mPa · s. Thus, the phosphor paste composition of Example 1 was manufactured.

Example 2 2,6-, which is an antioxidant
The addition amount of di-tert-butyl-p-cresol was set to 0.1.
A phosphor paste composition of Example 2 was manufactured in the same manner as the phosphor paste composition of Example 1 except that the amount was changed to 2 parts by weight instead of 2 parts by weight.

Example 3 As an antioxidant, 2,6-
Instead of di-tert-butyl-p-cresol, 2,
The phosphor paste composition of Example 3 was prepared in the same manner as the phosphor paste composition of Example 1 except that 2′-methylenebis- (4-methyl-6-tert-butylphenol; Yoshinox 2246 manufactured by Yoshitomi Pharmaceutical Co., Ltd.) was used. Manufactured.

COMPARATIVE EXAMPLE The fluorescent paste of Comparative Example was prepared in the same manner as the phosphor paste composition of Example 1 except that 2,6-di-tert-butyl-p-cresol, an antioxidant, was not added. A body paste composition was produced.

(Evaluation of Phosphor Paste Composition) With respect to each of the phosphor paste compositions of Examples 1 to 3 and Comparative Example obtained as described above, the viscosities immediately after production and the viscosities of these after being left at room temperature for 100 days Were measured, and the ratio of the viscosity after standing for 100 days to the viscosity immediately after production was calculated as a percentage, and this was defined as a viscosity retention ratio. The respective viscosities were measured at a shear rate of 5 using a viscometer (Rheostress RS-50).
The value of (1 / s) was measured. Table 1 shows the results.

Further, each phosphor paste composition is applied on a glass plate, dried at 120 ° C. for 30 minutes, and then heated at a rate of 10 ° C./min to 450 ° C.
Baking at 60 ° C. for another 60 minutes to form each fluorescent film,
The emission luminance of each phosphor film when irradiated with 47 nm vacuum ultraviolet rays was measured under the same conditions, and the emission luminance of the phosphor film obtained from the phosphor paste composition of the comparative example at this time was 100%. Table 1 shows the relative values obtained when

[0024]

[Table 1]

As can be seen from the results in Table 1, Examples 1 to
Each of the phosphor paste compositions of No. 3 has a high viscosity retention rate,
The change in viscosity over time when left at room temperature for 00 days was small, and the viscosity stability was very good. Among them, 2,6-di-substrate which has substantially no heat loss at 350 ° C. or higher.
No decrease in luminance was observed in the phosphor paste compositions of Examples 1 and 2 in which tert-butyl-p-cresol was added as an antioxidant, while a phosphor film using the phosphor paste composition of the present invention The emission luminance of (Examples 1 to 3) was almost the same as that of the phosphor film using the conventional phosphor paste composition containing no antioxidant (Comparative Example), and the antioxidant was contained. The emission luminance was not reduced or hardly decreased due to.

[0026]

As described above, the phosphor paste composition of the present invention has the above-mentioned structure, so that a decrease in viscosity during storage is significantly suppressed, and a phosphor paste composition having more stable properties over time can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) H01J 31/15 H01J 31/15 E (72) Inventor Hitoshi Inoue 1060 Narita, Odawara-shi, Kanagawa Kasei Optonix Co., Ltd. 4H001 CA01 XA05 XA08 XA12 XA13 XA14 XA16 XA30 XA39 XA56 XA64 YA13 YA25 YA29 YA47 YA63 YA65 4H025 AA15 5C036 EE02 EE14 EF16 EG36 EH12 5C040GG

Claims (7)

[Claims] 1. A phosphor paste composition for forming a phosphor film obtained by dispersing a phosphor in a solvent containing a binder resin, wherein the phosphor paste contains an antioxidant in the composition. Composition. 2. The method according to claim 1, wherein the antioxidant is a compound having substantially no heat loss at 350 ° C. or higher.
3. The phosphor paste composition according to item 1. 3. The phosphor paste composition according to claim 1, wherein the antioxidant is a phenolic antioxidant. 4. The method according to claim 1, wherein the phenolic antioxidant is 2,6-
The phosphor paste composition according to claim 3, wherein the phosphor paste composition is di-tert-butyl-p-cresol. 5. The method according to claim 1, wherein the content of the antioxidant is 0.05 to 10 parts by weight based on 100 parts by weight of the binder resin. Phosphor paste composition. 6. The phosphor paste composition according to claim 5, wherein the content of the antioxidant is 0.3 to 3 parts by weight based on 100 parts by weight of the binder resin. 7. The phosphor paste composition according to claim 1, wherein the binder resin is an ethylcellulose resin.