JPH05132668A - Formation of highly light-transmitting fluorescent membrane - Google Patents

Abstract

(57) [Summary] [Structure] (i) A lanthanoid sol obtained by hydrolyzing an alkoxide of a lanthanoid metal,
A mixture with an aluminum sol obtained by hydrolyzing an aluminum alkoxide, (ii) a sol obtained by hydrolyzing a mixture of a lanthanide metal alkoxide and an aluminum alkoxide, and (iii) a lanthanoid system After gelling at least one sol of a composite lanthanoid aluminum sol obtained by hydrolyzing an alkoxide of a composite of a metal and aluminum, and then 300 ° C. to 1300 ° C.
A method for producing a lanthanoid-based aluminate phosphor, which comprises firing at the temperature of. [Effect] The lanthanoid aluminate phosphor is obtained by firing at a low temperature for a short time, and the product has a high luminance ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a highly translucent fluorescent film. More specifically, the present invention relates to a method of forming a highly translucent fluorescent film by gelling a sol composed of phosphor constituent components. In the present specification, "high translucent fluorescent film"
The term "phosphor film" refers to a phosphor film having very few voids in the above-mentioned phosphor film, which is transparent or has very few irregular reflections and high translucency (including a plate-like body).

[0002]

2. Description of the Related Art In most cases, a phosphor is used in the form of a phosphor film formed by collecting fine particles having a size of several μm to several tens of μm. Since the fluorescent film is composed of fine particles of this size, the following problems may occur. In other words, even if fluorescence is generated from particles of a certain phosphor, the light hits the particles of another phosphor several times before it goes out of the fluorescent surface, and receives irregular reflection on the surface. To go out of the fluorescent screen. Therefore, in the case of the fluorescent screen of the cathode ray tube, since the fluorescent light emitted from the inner surface is viewed from the outside, the influence of this irregular reflection becomes strong. As a result, "fog" is generated in the image, the contrast is deteriorated, and the brightness is lowered.

Therefore, if it is possible to form a fluorescent film which is not composed of fine particles and has no voids between particles or a fluorescent film close to it, the brightness is improved and the contrast and sharpness are remarkably improved.

Conventionally, the following methods have been used to obtain such a highly translucent film.

One is a vacuum vapor deposition method. In this method, ordinary phosphor powder is put in a vapor source and vapor-deposited on a vapor-deposited plate at a vacuum degree of 5 × 10 ⁻⁵ mmHg or more. Here, if vapor deposition is stopped midway, the composition of the raw material phosphor and that of the resulting phosphor film will differ, so it is necessary to deposit all of them. In addition, the components that are likely to evaporate in the raw material evaporate first, and even if all of the raw material is vapor-deposited, a phosphor screen having a composition that is considerably different depending on the phosphor is likely to be formed.

The highly translucent fluorescent film thus formed exhibits almost no fluorescence as it is. It is said that this is because the activator is not completely incorporated in the matrix of the phosphor, and most of the matrix is in an amorphous state and not in a crystalline state. Therefore, when the vapor-deposited film is appropriately heated, the host is crystallized and the activator is diffused into the host to emit light.

The phosphor to which this method is most suitable is a self-activating phosphor. The heat treatment time and temperature must be controlled under extremely severe conditions, which is actually quite difficult. The method considered there is to heat a vapor deposition target plate in advance and perform vapor deposition. According to this method, the vapor deposition time can be shortened and the processing temperature can be lowered.

Another method for producing a highly translucent fluorescent film is a gas phase reaction method (chemical vapor deposition). This is to adhere the phosphor generated by the gas phase reaction onto the substrate. This method can be used for zinc sulfide-based phosphors. Specifically, hydrogen sulfide is injected into a container connected to a vacuum system at a pressure of 1 to 2 mmHg. The substrate held inside the container has been heated to 500 to 600 ° C. in advance. A small amount of a mixture of metallic zinc and manganese chloride is dropped into this container. This reacts with hydrogen sulfide,
The generated ZnS: Mn adheres to the substrate.

However, in the above gas phase reaction method, the types of phosphors that can be manufactured are limited. Therefore, the sol-gel method was proposed. Here, the "sol-gel method" forms a sol by hydrolyzing an organic acid metal compound or metal salt of a desired phosphor compound such as a metal alkoxide or metal acetate as a starting material, and gels the sol. Is the way.

The sol-gel method will be described below by taking as an example a composite metalate phosphor (hereinafter referred to as a lanthanoid aluminate phosphor) in which the starting material is a metal alkoxide and the phosphor is a lanthanoid metal and aluminum.
The lanthanoid-based aluminate phosphor is conventionally mixed by sufficiently mixing the lanthanoid-based metal oxide and aluminum oxide, which are the base material, and the lanthanoid-based metal oxide, which is the activator, with a flux or the like if necessary. Was added and the mixture was fired at a high temperature of 1500 ° C. to 2000 ° C. or higher for 10 hours or more.

[0011]

However, according to such a conventional method, the lanthanoid-based aluminate phosphor obtained is a powder or a phosphor having a non-uniform shape. Therefore, in order to obtain a desired highly translucent fluorescent film, it is necessary to use a method such as vapor deposition. Further, in the conventional method, since the baking temperature is high and it is necessary to perform baking for a long time, it cannot be easily manufactured, and this is a major industrial problem.

[0012]

The present invention is fundamentally different from the vapor deposition method and the vapor phase reaction method described above, and is to produce a highly translucent fluorescent film by using the sol-gel method. This method
The present invention provides a highly transparent fluorescent film that is significantly cheaper than the conventional method, and its industrial advantage is immeasurable.

In order to solve the above-mentioned problems of the prior art, the present inventor has various methods for obtaining a lanthanoid-based aluminate fluorescent film having a desired shape and particle size, which exhibits a high light-transmitting property at a lower temperature. As a result of repeated research, when gelling the sol obtained by hydrolyzing the alkoxide of the metal component composing the target lanthanoid-based aluminate fluorescent film, the subsequent calcination is performed at a low temperature for a short time. It has been found that a lanthanoid-based aluminate highly translucent phosphor having a desired shape and particle size can be easily obtained, and exhibits high translucency.

That is, the method for producing a lanthanoid-based aluminate phosphor of the present invention comprises: (i) a lanthanoid sol (two types of base and activator) obtained by hydrolyzing an alkoxide of a lanthanoid-based metal; Mixture with aluminum sol obtained by hydrolyzing aluminum alkoxide, (ii) Obtained by hydrolyzing mixture of lanthanoid metal alkoxide (two kinds of base and activator) and aluminum alkoxide At least one sol of the obtained sol and (iii) the complex lanthanoid aluminum sol obtained by hydrolyzing the alkoxide of the complex of the lanthanoid-based metal and aluminum is subjected to gelation at 300 ° C to 1 ° C.
It is characterized by firing at a temperature of 300 ° C.

The lanthanoids are La, Ce, Pr, Nd, Pm, Sm, which are 15 rare earth elements ranging from lanthanum having an atomic number of 57 to lutetium having an atomic number of 71.
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
It is a general term for u and Y of atomic number 39.

The sol mixture (i) is obtained, for example, as follows: Anhydrous lanthanide halide and an alkali metal alkoxide are reacted in alcohol, and then the solvent is replaced with benzene to form an alkali metal halide. Are precipitated and filtered off to obtain a benzene solution of lanthanoid alkoxide. Next, water is added to this solution and hydrolysis is performed to obtain a lanthanoid sol which is a sol of lanthanoid hydroxide. On the other hand, for example, 100 mol of water is added to 1 mol of aluminum alkoxide,
An aluminum sol is obtained by hydrolyzing at 5 ° C., and further adding 0.1 mol of hydrochloric acid to 1 mol of the above aluminum alkoxide and peptizing at 95 ° C. A sol mixture (i) is obtained by mixing the lanthanoid sol and the aluminum sol.

The above sol (ii) is obtained, for example, as follows: The lanthanoid alkoxide and the aluminum alkoxide are dissolved in benzene by adjusting the amount ratio so that the desired lanthanoid aluminate phosphor composition ratio is obtained. To do. Next, this solution is refluxed for 4 hours, and then water is added thereto for hydrolysis to obtain sol (ii).

The above composite sol (iii) can be obtained, for example, as follows: An alkali metal is reacted with an excess of alcohol in a nitrogen stream to synthesize an alkali metal alcoholate, and an aluminum alkoxide equimolar to the alkali metal is added to the alkali metal alcoholate. In addition, the mixture is refluxed for about 2 hours to synthesize an alkali metal aluminum alkoxide. This is added to a lanthanoid halide alcohol solution and refluxed for 4 hours for reaction. Then, the solvent is replaced with benzene, and the produced alkali metal halide is precipitated and removed by filtration to obtain a benzene solution of a lanthanoid aluminum alkoxide. Next, water is added to this solution for hydrolysis to obtain a composite lanthanoid aluminum sol (iii). In this case, a small amount of lanthanoid alkoxide or aluminum alkoxide may be added to the lanthanoid aluminum alkoxide before the hydrolysis in order to facilitate formation of the lanthanoid aluminate phosphor having a desired composition.

The halogen of the halide used in the above sol preparation may be any of fluorine, chlorine, bromine and iodine, but chlorine is most preferable from the viewpoint of reaction stability. The alcohol used is a monohydric alcohol such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, s-butyl alcohol, amyl alcohol or isoamyl alcohol, but isopropyl alcohol is particularly colored. It is preferable because it does not cause such problems.

The gelation of the sol of (i) (ii) and / or (iii) in the method of the present invention is carried out by a method such as removing water. In order to form a transparent thin film or thick film by this gelation, it is advisable to put the sol in a container having a small surface energy such as polystyrene, polypropylene or Teflon and dry it. A method of coating on a quartz substrate or the like is also good.

Further, in order to obtain a spherical powder by gelation, the above sol is stirred in a non-aqueous solvent to which a surfactant is added, and the difference in interfacial tension with the sol solvent is utilized to form a spherical sol. After that, water is removed and gelled. By adjusting the stirring speed at this time, the diameter is several μm to about 1 mm.
A degree of spherical gel material is obtained. In the method of the present invention, the gel material formed as described above is fired at a temperature of 300 ° C. to 1300 ° C. for a short time to obtain a desired highly translucent phosphor film composed of a lanthanoid aluminate phosphor. can get. The emission spectrum of the obtained phosphor film was exactly the same as that obtained by the conventional method.

Although the starting material has been described by using the metal alkoxide, the high translucency can be obtained by a method other than the present method, such as hydrolysis of an organic metal acid which is a reaction product of an organic acid and a metal halide, or hydrolysis of a metal halide. Fluorescent fluorescent film.

Examples of phosphors that can be produced in the present invention include phosphors for color TV as indicated by P number,
There are black and white TV phosphors, various electron tube phosphors, low speed electron tube phosphors, electroluminescent phosphors, photoconductors, lamp phosphors, infrared application phosphors, phosphorescent phosphors, radiation phosphors, etc. However, these other known phosphors can also be made.

Particularly, the oxide phosphor is easy to manufacture.

The transparency of the phosphor obtained in the present invention was measured as a transmittance.

The transmittance was measured at a thickness of 30 m / m and a thickness of 1
Average particle size of 6 μm by conventional method on m / m quartz glass
The lanthanoid aluminate phosphor of No. 1 was coated by sedimentation coating to a thickness of 100 μm. The transparent phosphor in the present invention is
The above-mentioned quartz glass was coated with the lanthanoid aluminate sol and naturally dried to obtain a 100 μm smooth gel body. This was baked at 1000 ° C. for 1 hour to obtain an aluminate phosphor.

The measurement sample obtained here was placed horizontally on an optical bench, irradiated with light from a tungsten lamp light source at a distance of 100 m / m, passed through the measurement sample, and then separated from the sample by 10 m / m. The light was received by a photocell, and the transmittance of a 1 m / m-thick quartz glass not coated with the phosphor was measured. As a result, the transmittance of the phosphor film by the conventional method is 5 to
It was in the range of 10%, but in the highly translucent fluorescent film according to the present invention, it was in the range of 30 to 90%.

As a field of application of the present invention, any place where a fluorescent film has been conventionally used can be used without any problem. Further application to high definition tubes is possible. This is a case of a penetration type cathode ray tube, and at present, a particulate phosphor is coated inside the cathode ray tube. The application of the highly translucent fluorescent film of the present invention is performed as follows. B, G, R
The three colors are coated in three layers, respectively, and a highly transparent insulator (for example, a highly transparent Al obtained by the sol-gel method) is provided between the three layers.
O ₃ and SiO ₂ film) are inserted. This makes it possible to obtain a penetration type cathode ray tube having higher brightness and better resolution than ever before.

Examples will be described below.

[0030]

【Example】

[Example 1] High-purity yttrium oxide and ammonium chloride were mixed and reacted at a temperature of 350 ° C for 1 hour, then anhydrous yttrium chloride as a reaction product was extracted with ethanol, and the solvent ethanol was replaced with isopropyl alcohol. did. Further, metallic sodium was added to a mixed solution of isopropyl alcohol and benzene, and the alcoholate obtained by refluxing at 82 ° C. was mixed with the above anhydrous yttrium chloride solution, further refluxed at 82 ° C., and then the solvent was replaced with benzene. Sodium chloride was removed by filtration to obtain a benzene solution of yttrium isopropoxide.
Water was added to this solution for hydrolysis to obtain yttrium sol.

A cerium sol was obtained in the same manner.

Next, 100 mol of water is added to 1 mol of the aluminum alkoxide, and hydrolysis is carried out at 75 ° C. Further, 0.1 mol is added to 1 mol of the aluminum alkoxide.
An aluminum sol was obtained by adding molal hydrochloric acid and peptizing at 95 ° C.

The yttrium sol and the aluminum sol thus obtained are respectively (a) 1: 1 and (b) in a molar ratio.
3: 5 and (c) 1: 2, and 2.5 × 10 ⁻³ mol of cerium sol was mixed with 1 mol of the mixture, and the mixture was put in a Teflon vessel and dried at room temperature to form a transparent gel. A body membrane was obtained. Then, this is baked at 1000 ° C. for 2 hours to obtain (a) YAlO ₃ : Ce + Y3Al ₅ O ₁₂ : Ce (b), respectively.
A highly translucent phosphor film composed of a yttrium cerium aluminate phosphor whose composition formula is represented by Y ₃ Al ₅ O ₁₂ : Ce and (c) Y ₂ Al ₄ O ₉ : Ce was obtained. This was identified by X-ray diffraction.

[Example 2] Yttrium isopropoxide, aluminum isopropoxide and cerium isopropoxide were mixed in a benzene solution at a molar ratio of 3: 5: 5 x 10 ^-3 , and the temperature was 82 ° C. After refluxing for 4 hours, the mixture was hydrolyzed by adding sufficient water to obtain a mixture of yttrium sol, aluminum sol and cerium sol.

When this was gelled and fired in the same manner as in Example 1, a highly translucent phosphor film composed of a cerium-activated yttrium aluminate phosphor having a composition formula of Y ₃ Al ₅ O ₁₂ : Ce was obtained. It was This was identified by X-ray diffraction.

[Example 3] Metal potassium was reacted with an excess of isopropyl alcohol in a nitrogen stream to synthesize potassium isopropoxide [i-C ₃ H ₇ OK], which was equimolar to aluminum isopropoxide. It was synthesized potassium aluminum isopropoxide _{{KAl (i-OC 3 H} 7) 4} was refluxed for 2 hours added propoxide. This was refluxed for 4 hours in addition to yttrium chloride isopropyl alcohol solution, and cerium chloride isopropyl alcohol solution, it was synthesized yttrium, cerium aluminum isopropoxide {Y · Ce [Al (i -OC 3 H 7) 4] 3}. The reaction by-product, KCl, was filtered after replacing the solvent with benzene. Excess distilled water was added to the obtained alkoxide and refluxed to obtain a composite yttrium aluminum sol.

This was molded by gelation in the same manner as in Example 1 and baked at 1000 ° C. to give a composition formula of Y ₃
A highly translucent phosphor film made of a cerium-activated yttrium aluminate phosphor of Al ₅ O ₁₂ : Ce was obtained. This was identified by x-ray diffraction.

Example 4 A gadolinium sol was obtained in the same manner as in Example 1 except that high-purity gadolinium oxide was used instead of the high-purity yttrium oxide as the starting material.

The gadolinium sol, the aluminum sol, and the cerium sol were mixed at a molar ratio of 3: 5: 5 × 10 ⁻³ , molded by sol formation, and further fired. The composition ratio was Gd ₃ Al ₅ O ₁₂ : A highly translucent phosphor film composed of a cerium-activated gadolinium aluminate phosphor represented by Ce was obtained. This was identified by X-ray diffraction.

[0040] [Example 5] definitive yttrium aluminum, cerium isopropoxide obtained in a manner similar to Example 3 {Y · Ce [Al ( i-O (C 3 H 7) 4] 3}
0.4 mol of aluminum isopropoxide [Al (i-OC ₃ H ₇ ) ₃ ] was added to 1 mol of the above, and the mixture was refluxed for 4 hours, sufficiently mixed, and then hydrolyzed to obtain a sol.

When this sol is gelled and then baked at 1000 ° C. for 2 hours, a highly translucent phosphor film composed of a cerium-activated yttrium aluminate phosphor having a composition formula of Y ₃ Al ₅ O ₁₂ : Ce is obtained. It was This was identified by X-ray diffraction.

[0042] Part 1 mol to Example 6 Example definitive yttrium aluminum, cerium isopropoxide obtained in a manner similar to 3 {Y · Ce [Al ( i-OC 3 H 7) 4] 3} 0.2 mol of yttrium isopropoxide [Y (i-OC ₃ H ₇ ) ₃ ] was added, and the mixture was refluxed for 18 hours to sufficiently mix them, followed by hydrolysis to obtain a sol.

When this sol was gelled and then baked at 1000 ° C. for 2 hours, a highly translucent phosphor film composed of a cerium-activated yttrium aluminate phosphor having a composition formula of YAlO ₃ : Ce (hexagonal) was obtained. Was given. In addition, the gel above 12
The composition formula is YAlO ₃ : Ce when baked at 00 ° C. for 2 hours.
A highly translucent phosphor film composed of a cerium-activated yttrium aluminate phosphor represented by (orthorhombic, perovskite type) was obtained. These things were identified by X-ray diffraction.

Example 7 A europium sol was obtained in the same manner as in Example 1. This europium sol was mixed with the yttrium sol obtained in Example 1 at a molar ratio of 1: 5 × 10 ⁻³ , gelled, and then calcined at 1100 ° C. for 2 hours to give a composition formula of Y ₂ O ₃ : Eu. A highly translucent phosphor film consisting of the red-emitting phosphor shown was obtained.

[Example 8] Silica gel, terbium sol and europium sol were obtained in the same manner as in Example 1. The various sols obtained above and the yttrium sol and the cerium sol obtained in Example 1 were mixed in the following formula.
Y ₂ SiO ₅ : Eu, Y ₂ SiO ₅ : Tb, Y ₂ SiO ₅ : C
e (however, Eu, Tb, and Ce are 5 × 10 ⁻⁵ mol) These sols were gelled and then fired at 1200 ° C. for 2 hours to obtain a phosphor represented by the above formula. It showed red, green and blue respectively.

[Example 9] The yttrium sol of Example 7 was gelated to obtain spherical yttrium oxide having a diameter of 8 µm. Europium sol, terbium sol, and cerium sol were coated on the surface to a thickness of 0.5 μm, and after gelling, they were baked at 1000 ° C. Europium by firing,
Terbium and cerium diffused into yttrium and became highly translucent phosphor particles. This was identified by X-ray diffraction.

[0047]

As described above, according to the method of the present invention, a lanthanoid aluminate phosphor can be obtained by firing at a lower temperature and a shorter time than the conventional method, and the energy consumption is small. Further, according to the method of the present invention, when a molded product is to be obtained, a desired shape is immediately obtained, and when a granular product is to be obtained, it is easy to control the particle size. There is a great advantage that you get Still another advantage is that a high brightness ratio can be obtained as compared with the conventional powder product. That is, according to the present invention, as compared with that obtained by the conventional method, 10
A brightness ratio improvement of up to 20% is obtained.

Claims (2)

[Claims] 1. The above-mentioned fluorescence is obtained by hydrolyzing a metal alkoxide, an organic acid metal compound or a metal salt containing each element of the matrix constituent element of the phosphor and each element of the phosphor activator constituent elements. After obtaining a sol containing each element necessary for body constitution, and then putting the sol in a vessel having a desired shape to form a gel and form a film, 300 ° C to 1300 ° C
A method for forming a highly translucent fluorescent film, which comprises firing at. 2. The firing temperature is 500 ° C. to 1300 ° C.
The method for forming a highly translucent fluorescent film according to claim 1, wherein