JP2519890B2 - Method for producing luminescent composition - Google Patents

Description

TECHNICAL FIELD The present invention mainly relates to a method for producing a light-emitting composition which exhibits high-efficiency light emission under a slow electron beam excitation with an accelerating voltage of 1 kv or less, particularly 100 v or less. .

(Prior Art) As a phosphor that emits light with high efficiency by low-speed electron beam excitation, zinc-activated zinc oxide phosphor (ZnO: Zn) that emits green-white emission, europium-activated tin oxide fluorescence that emits orange-red emission The body (SnO ₂ : Eu) and the like are known, and in particular, ZnO: Zn has been practically used for a long time as a phosphor for a low-speed electron beam excitation fluorescent display tube (hereinafter referred to as “fluorescent display tube”). After that, even if the phosphor has a very low luminous efficiency under low-speed electron beam excitation, a predetermined amount of conductive metal oxide such as In ₂ O ₃ , ZnO, SnO ₂ or conductive material such as CdS, Cu ₂ S, etc. Of a luminescent composition obtained by mixing a conductive substance such as a conductive metal sulfide (in the present specification, the phosphor and the conductive substance are simply mechanically mixed, or "Luminescent composition" is a generic term for compositions obtained by attaching or coating substances.
Has been found to exhibit highly efficient light emission by slow electron beam excitation, and such a light emitting composition can be obtained by selecting a phosphor, which is one of its constituent components, to obtain a desired light emission composition. Since it emits a luminescent color, it has been widely put into practical use in recent years as a fluorescent display tube for multicolor display together with the conventionally used ZnO: Zn.

(Problems to be Solved by the Invention) By the way, since a conventional light emitting composition has a relatively simple process, it is necessary to mechanically mix a predetermined amount of a phosphor and a conductive substance with a mortar, a ball mill or the like. The method most commonly used is However, the conventional luminescent composition thus obtained is ZnO:
Since the emission efficiency under low-speed electron beam excitation is lower than that of Zn,
Various attempts have been made to improve it, for example, a method of controlling the particle size distribution of a conductive substance used as a constituent component of a light emitting composition (Japanese Patent Publication No. 59-33153 and Japanese Patent Publication No. 59-331).
No. 55, Japanese Patent Publication No. 60-46149, etc.) has been proposed, but it is desired to further improve the efficiency of fluorescent compositions with the colorization of fluorescent display tubes and the expansion of their fields of use. .

The present invention has been made in view of the above demands, accelerating voltage is 1kv or less, particularly 100v or less under slow electron beam excitation, more highly efficient light emission compared to the light emitting composition obtained by the conventional production method. It is an object of the present invention to provide a method for producing the luminescent composition shown.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the inventors of the present invention have a method of mixing a phosphor and a conductive substance, such as the type and property of the conductive substance which is one of the constituents of the luminescent composition. As a result of earnest studies on the above, it was found that a phosphor composition and a sol composition containing indium oxide as a main component are mixed and dried to obtain a light emitting composition having higher efficiency than conventional ones. The present invention has been completed.

The method for producing a luminescent composition of the present invention is mainly composed of indium oxide obtained by adding a solution containing phosphor particles, an inorganic indium salt whose pH is adjusted to a range of about 0.1 to 3, and an anion exchange resin. And a step of dehydrating the mixture, and then drying the mixture, the conductive metal oxide containing indium oxide as a main component on the surface of the phosphor particles. It is characterized by adhering particles or a film of.

(Example) Next, the manufacturing method of the present invention will be described in more detail.

First, a phosphor exhibiting a desired emission color and an indium oxide sol or indium tin sol composition, indium
Sol composition such as antimony sol composition (these are collectively referred to as "sol composition containing indium oxide as a main component" hereinafter)
And) are mixed in a predetermined amount and thoroughly mixed using a stirrer.

As the sol composition containing indium oxide as a main component used in the production method of the present invention, for example, a sol composition produced by a known method as disclosed in JP-A-59-219810 can be used. That is, InCl ₃ , an inorganic indium salt such as In (NO ₃ ) ₃ or SnCl ₄ , an aqueous solution of an inorganic indium salt containing SbCl _5, etc., a solution of a mineral acid solution methanol solution or an ethanol solution is prepared, and ions A method of contacting with an exchange resin, a method of obtaining by a liquid phase neutralization reaction of the inorganic indium salt and an alkaline substance, a gel containing indium oxide as a main component once by a liquid phase neutralization reaction of the inorganic indium salt and an alkaline substance It can be produced by a method of obtaining a composition and then hydrothermally treating this gel composition to form a sol.

Note that, from the viewpoint that the luminous efficiency of the obtained light-emitting composition can be further improved, among these, a sol composition containing indium oxide as a main component obtained by the method of bringing the inorganic indium salt solution into contact with an ion exchange resin. It is particularly preferable to use a substance, and in this case, the solvent of the inorganic indium salt solution is usually water, a mineral acid and acetone, or methanol, although it depends on the solubility of the inorganic indium salt used, the dispersibility of the prepared sol, and the like. , Ethanol, ethylene glycol,
A single or mixed solution of organic solvents such as methyl cellulose is used. Then, in order to further improve the luminous efficiency of the resulting luminescent composition, the pH value of the solution of the inorganic indium salt is adjusted by adding a mineral acid so that the pH value is in the range of about 0.1 to 3, and then the pH value of the solution is adjusted. Obtained by separating the ion-exchange resin when the pH value in the liquid reaches approximately 4 to 10 by adding an amount of anion-exchange resin having anion-exchange group of about 0.5 equivalent or more of the total amount of anion of It is preferable to use a sol composition containing indium oxide as a main component.

On the other hand, the phosphor used in the production method of the present invention is not particularly limited, any phosphor may be used depending on the emission characteristics of the phosphor, in particular ZnS: Zn, Zn
S: Au, ZnS: Cu, ZnS: Ag, ZnS: Ag, Al, ZnS: Au, Al, ZnS: Cu, Al, Z
n (S, Se): Ag, Zn (S, Se): Ag, Al, (Zn, Cd) S: Cu, (Zn, C
d) S: Cu, Al, (Zn, Cd) S: Ag, (Zn, Cd) S: Ag, Al, Zn (S, S
e): Cu, Zn (S, Se): Cu, Al, (Zn, Cd) S: Au, Al and other sulfide-based phosphors and sulfur-selenide-based phosphors, especially high efficiency emission A composition is obtained.

In the production method of the present invention, the optimum addition amount of the mixed sol composition containing indium oxide as a main component varies depending on the kind of the phosphor to be used. When the contents are the same, in order to obtain a light-emitting composition with higher brightness than that produced by the conventional method, the conductivity of the indium oxide-based sol composition containing indium oxide as the main component is added. The amount of the functional metal oxide is about 0.5 to 3 of the resulting luminescent composition.
It is preferable that the amount be equivalent to 0% by weight.

Then, the mixture of the phosphor and the sol composition containing indium oxide as the main component, obtained as described above, is dehydrated and dried at a temperature of 50 ° C. to 200 ° C. It is possible to obtain a light emitting composition comprising particles of a conductive metal oxide as a component or phosphor particles to which a film is attached or coated.

FIG. 1 shows a light emitting composition comprising a (Zn _0.64 , Cd _0.36 ) S: Ag, Cl phosphor and In ₂ O ₃ and the content of In ₂ O _{3 in} the light emitting composition and the light emitting composition It shows the relationship with the relative luminous efficiency when excited by an electron beam to emit light, the curve shown by the solid line and the curve shown by the broken line are the luminescent composition manufactured by the manufacturing method of the present invention and the conventional one, respectively. Method {(Zn _0.64 , Cd _0.36 ) S: Ag, Cl phosphor and In ₂ O ₃ mechanically mixed}. In the figure, the content of In ₂ O ₃ (horizontal axis) is the analytical value of In ₂ O ₃ contained in the obtained light-emitting composition in the case of the curve shown by the solid line, and in the case of the curve shown by the broken line Indicates the amount of In ₂ O ₃ added at the time of manufacture.

As is apparent from FIG. 1, according to the present invention (solid line), the content of In ₂ O ₃ can be reduced as compared with the conventional method (broken line), and a more efficient light emitting composition can be obtained. . In addition, when comparing the respective luminescent compositions having the optimum In ₂ O ₃ content, the luminescent efficiency of the luminescent composition produced by the production method of the present invention is significantly higher than that produced by the conventional method. high.

2a and 2b show In ₂ O _{3 on} the surface of (Zn _0.64 , Cd _0.36 ) S: Ag, Cl phosphor particles by the manufacturing method of the present invention.
An example of a photomicrograph of a light-emitting composition having a film made of In ₂ O ₃ attached thereto and a conventional light-emitting composition obtained by mixing the same phosphor and In ₂ O ₃ particles by a conventional method is shown. It is a thing. In the luminescent composition produced by the method for producing obvious to the present invention from Figure 2, the outer a small amount of In ₂ O ₃ adhered to the surface of the phosphor particles, the surface of the phosphor particles In ₂ You can see that it is covered with a transparent O ₃ film.

Example 1 52 g of indium nitrate [In (NO ₃ ) ₃ .3H ₂ O] was dissolved in 400 cc of ethyl alcohol and 20 cc of concentrated nitric acid, and the total amount thereof was 80
Pure water was added to 0 cc to prepare an aqueous solution of indium nitrate, and NaOH was further added to adjust the pH value of the solution to 2.0. Next, a 400 cc capacity ion-exchange resin (SA-10 manufactured by Nippon Rinshui KK) was added to this solution and stirred sufficiently until the pH value of the solution reached about 7, and then this ion-exchange resin was separated. 400 g of (Zn _0.64 , Cd _0.36 ) S: Ag, Cl phosphor was added to the indium oxide sol thus obtained, and the mixture was thoroughly stirred, dehydrated, and dried at a temperature of 150 ° C to obtain (Zn _0.64 , Cd _0.36 ) S: Ag, Cl Phosphor particles were provided with a light emitting composition (I) in which 5 wt% (actual analysis value) of indium oxide was attached.

For comparison, a luminescent composition (I ′) and ((n ′) containing a (Zn _0.64 , Cd _0.36 ) S: Ag, Cl phosphor and indium oxide at a weight ratio of 95: 5 and 80:20, respectively, were mixed. I ″) was produced.

The luminescent compositions (I) and (I ') thus obtained
For (I ″), the applied voltage and the anode current required to obtain the same emission brightness when excited with a low-speed electron beam were measured, and the relative emission efficiency of each light-emitting composition was determined to be 215,100 and The luminous efficiency of the luminous composition (I) is 110, and the luminous composition (I ′) having the same In ₂ O ₃ content as that of the luminous composition (I) and the optimum In ₂ O ₃ content manufactured by the conventional method. It was significantly higher than that of the luminescent composition (I ″).

Example 2 42 g of indium chloride (InCl ₃ .4H ₂ O) was dissolved in 1.6 l of water, and NaOH was added to prepare an indium chloride solution having a pH value of 2.8. To this solution was added an ion exchange resin with a capacity of 800 cc (WA-30 manufactured by Nippon Rinshui KK), and the pH value of the solution was about 6.0.
The ion-exchange resin was separated by sufficiently stirring until it became. 40% in the indium oxide sol thus obtained
After adding 0 g of ZnS: Au, Al phosphor and thoroughly mixing, dehydration and drying at a temperature of 150 ° C.
A luminescent composition (II) having indium oxide attached at a weight percentage (actual analysis value) was obtained.

For comparison, ZnS: Au, Al phosphor and indium oxide
Luminescent compositions (II ′) and (II ″) were produced by mixing with a ball mill in a weight ratio of 5: 5 and 80:20, respectively.

The luminescent composition (II), (II ′) thus obtained
And (II ″) were excited with a slow electron beam and the luminous efficiency of each luminescent composition was measured in the same manner as in Example 1. The relative values were 180, 100 and 120, respectively, and the luminescent composition (II) Luminous efficiency of manufactured by the conventional method,
Significantly higher than the luminescent composition (II) and In ₂ O ₃ content is identical luminescent composition (II ') and optimal In ₂ O ₃ content of the luminescent composition (II ").

Example 3 ZnS: Cu, Al phosphor particles were prepared in the same manner as in Example 1 except that 200 g of ZnS: Cu, Al was used as the phosphor instead of 400 g of (Zn _0.64 , Cd _0.36 ) S: Ag, Cl. Luminescent composition (III) with 10% by weight (actual analysis value) of indium oxide deposited on the surface
I got

For comparison, ZnS: Cu, Al phosphor and indium oxide
Luminescent compositions (III ′) and (III ″) were produced by mixing in a ball mill in a weight ratio of 0:10 and 80:20, respectively.

The light emitting composition (III), (II
Example 1 by exciting I ′) and (III ″) with a slow electron beam
When the luminous efficiency of each luminescent composition was measured in the same manner as above, the relative luminous efficiencies thereof were 190, 100 and 110, respectively.
, And the luminous efficiency of the light emitting composition (III) was prepared by a conventional method, the light emitting composition (III) and the same In ₂ O ₃ content of the luminescent composition (III ') and of the optimal In ₂ O ₃ content It was significantly higher than the luminous composition (III ″).

Example 4 25.2 g of indium chloride (InCl ₃ .4H ₂ O) and stannic chloride (S
nCl ₄ / 3H ₂ O) 1.8 g and dissolved in hydrochloric acid, the total amount of this is 2.4 l
To prepare an indium chloride solution containing stannic chloride, and then add NaOH to adjust the pH value of the solution to 2.
It was adjusted to be 0. Next, a 1000 cc capacity ion-exchange resin (SA-10 manufactured by Nippon Kokusui KK) was added to this solution, and the mixture was sufficiently stirred until the pH value of the solution became about 8.0, and then,
The ion exchange resin was separated. 400 g of ZnS: Ag, Al phosphor was added to the indium oxide / tin oxide sol thus obtained, and the mixture was thoroughly stirred, dehydrated, and dried at a temperature of 150 ° C. to obtain ZnS: Ag, Al phosphor. A luminescent composition (IV) was obtained in which 7.5% by weight (actual analysis value) of an indium oxide-tin oxide mixture containing 3% by weight of tin oxide was attached to the surface of the body particles.

For comparison, a luminescent composition prepared by mixing ZnS: Ag, Al phosphor and indium oxide containing 7.5% by weight of tin oxide at a weight ratio of 97: 3 and 90:10 respectively by a ball mill (I
V ') and (IV ") were produced.

The luminescent composition (IV), (IV ′) thus obtained
And (IV ″) were excited with a low-velocity electron beam to measure the luminous efficiency of each luminescent composition in the same manner as in Example 1. The relative luminous efficiencies of these were 250, 100 and 150, respectively.
The luminous efficiency of the luminous composition (IV) was produced by the conventional method. The luminous composition (IV ′) and the optimum indium oxide-tin oxide having the same indium oxide-tin oxide mixture content as the luminous composition (IV) were prepared. It was significantly higher than that of the luminescent composition (IV ″) containing the mixture.

(Effect of the invention) As described above, according to the production method of the present invention, it is possible to obtain a light-emitting composition that emits light with extremely high efficiency under excitation with a slow electron beam, as compared with the conventional light-emitting composition. It is possible to obtain a light emitting composition exhibiting highly efficient light emission by reducing the addition amount of the conductive metal oxide as compared with the above light emitting composition.

[Brief description of drawings]

FIG. 1 illustrates the relationship between the content of a conductive substance in the light emitting composition obtained by the production method of the present invention and the light emitting composition obtained by the conventional production method and the light emission efficiency under the slow electron beam excitation. It is a graph. FIG. 2 exemplifies photographs by an electron microscope showing the particle structures of the luminescent composition obtained by the production method of the present invention and the luminescent composition obtained by the conventional production method.

Continuation of the front page (56) References JP 55-151080 (JP, A) JP 56-2384 (JP, A) JP 59-140284 (JP, A) JP 61-127783 (JP , A) JP-A-55-135189 (JP, A)

Claims (1)

(57) [Claims] 1. A sol containing indium oxide as a main component, which is obtained by adding an anion exchange resin to a solution containing phosphor particles and an inorganic indium salt having a pH value adjusted to about 0.1 to 3. A light-emitting composition characterized by mixing a composition, dehydrating the mixture, and then drying the composition to deposit particles or a film of a conductive metal oxide containing indium oxide as a main component on the surface of the phosphor particles. Method of manufacturing things.