JP2010144111A - Sulfide phosphor particle having surface coating layer, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide sulfide phosphor particles which absorb excitation light and emit light, and are used for light-emitting elements such as LED, cause no degradation of fluorescence intensity, and have a surface coating layer in which moisture resistance has been improved remarkably, and to provide a method of manufacturing the particles efficiently. <P>SOLUTION: The method of manufacturing sulfide phosphor particles having a surface coating layer includes: a first process for obtaining sulfide phosphor particles (A) on the surface of which an aluminum organometallic compound is adsorbed as an underlying layer in predetermined conditions; a second process for obtaining sulfide phosphor particles (B) on the surface of which a silane organometallic compound film is formed in predetermined conditions; and a third process in which the sulfide phosphor particles (B) obtained in the second process is subjected to heat-treatment to obtain sulfide phosphor particles (C) on the surface of which a coating layer comprising an amorphous inorganic compound film containing an organic component is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sulfide phosphor particle having a surface coating layer and a method for producing the same, and more specifically, a sulfide phosphor particle that absorbs and emits excitation light used in a light emitting device such as an LED, The present invention relates to a sulfide phosphor particle having a surface coating layer with no strength reduction and significantly improved moisture resistance, and a method for efficiently producing the same.

White LEDs, which are expected to be used more widely in lighting applications, are broadly classified into high luminance types and high color rendering types. For example, an oxide phosphor composed of a compound phase represented by a composition formula: Sr ₂ SiO ₄ : Eu or Sr ₃ SiO ₅ : Eu is a phosphor used for a high-luminance type and excited from a blue LED. Yellow light is emitted by absorbing part of the light, and white light is obtained by mixing with blue excitation light. On the other hand, a sulfide phosphor composed of a compound phase represented by a composition formula: CaS: Eu, SrS: Eu, (Ca, Sr) S: Eu, or SrGa ₂ S ₄ : Eu is used for a high color rendering type. Color rendering is enhanced by coloring red and green.

Among these, in particular, the sulfide phosphor is known to generate hydrates on the surface due to water vapor or water in the air, and is degraded and deteriorated. There has been a problem that a decrease in luminance and a change in color tone occur due to a temperature increase caused by excitation light.
As a measure for improving the moisture resistance of such a phosphor, the following method has been proposed, but problems still remain.
(1) The surface of the particles is provided with a surface coating layer of silicone resin, epoxy resin, fluororesin, silica, zinc silicate, silicone oil, etc., so that there is no decrease in initial emission intensity, and It is said that moisture resistance is improved (for example, refer to Patent Document 1).
Although this method is a simple method of spraying and drying the coating material while rotating, there is a problem that it is not easy to uniformly coat the entire circumference of the fine powder or to control the film thickness. . Also, when silicone oil or resins are used, drying does not proceed and the fluidity of the powder decreases, so if this is forcibly dried, the particles will aggregate and be mixed in the LED resin. There was a problem that could not be.

In particular, as a measure for improving the moisture resistance of sulfide phosphors,
(2) In a method of forming a discontinuous glass layer having a thickness of 20 nm or more using alkoxysilane as the silane organometallic compound (for example, see Patent Document 2), the sulfide phosphor particles are bonded with alkoxysilane and When water for hydrolysis is added at the same time, when using a powder having low water resistance, for example, particles comprising a compound phase represented by the composition formula: SrS: Eu, the deterioration due to the influence of moisture is significant, and the heating temperature is reduced. When it is made higher, the deterioration becomes more severe and the particles themselves are dissolved.
(3) On the surface of the sulfide phosphor, a mercapto group silane coupling agent is used as a surface modifier, and further, an alkoxysilane is used as a silane organometallic compound, and hydrolyzed and condensed with ammonia water. In a method for forming a polymer film (see, for example, Patent Document 3), the pH is controlled using ammonia water to hydrolyze alkoxysilane, but before the particle surface is coated, the silanes react with each other. Wake up and produce fine particles. For this reason, even if fine particles are deposited, the film does not become dense, and there is a problem in that the light emission properties as a whole deteriorate due to aggregation of the released fine particles and mixing in the particles. In order to avoid this, a measure for reducing the reaction rate is also taken, but the processing time becomes longer and the productivity is inferior.

  However, as a result of measuring the moisture resistance of the phosphor obtained by the above-described measures for improving the moisture resistance of the sulfide phosphor, for example, when a phosphor having a coating layer is placed in a high-temperature humidified atmosphere, As a result, an eluate was generated from the phosphor surface, and a hydrate or carbonate was produced, resulting in a significant decrease in light emission characteristics. In particular, it has been found that these tendencies are remarkable in sulfide phosphor particles. By the way, when the moisture resistance of the phosphor itself is not improved as described above, the LED light emitting element is deteriorated immediately when used outdoors such as lighting and automobiles. Many causes of these deteriorations are in the film quality.

That is, the factors that determine the film quality depend on the coating conditions and the coating material, but other than that, defects in the film also have a great influence. For example, even when a film is formed on the particle surface, a film defect is generated when the organic substance is decomposed by heat treatment, and the particle deteriorates through moisture and moisture.
In order to avoid this, usually, the film thickness of the coating layer is increased. However, the most commonly used method of hydrolyzing and coating alkoxysilane can only obtain a film thickness of about 100 nm at most. That is, by adding an acid / alkali catalyst to water or a non-aqueous solvent and controlling the pH to hydrolyze / condense alkoxysilane, the alkoxysilane is slowly hydrolyzed / condensed to precipitate on the particle surface. The time required for the treatment is about 1 day. Further, since the treatment is performed in a dilute solution, only a small amount of coating can be performed per batch, resulting in high cost.
Under the circumstances described above, there is a demand for a method for efficiently producing sulfide phosphor particles having a surface coating layer with significantly improved moisture resistance.

Japanese Patent Laying-Open No. 2005-187797 (first page, second page) JP 2007-308537 A (first page, second page) JP 2006-188700 A (first page, second page)

  An object of the present invention is to provide sulfide phosphor particles that absorb and emit excitation light used in a light emitting device such as an LED in view of the above-described problems of the prior art, and do not have a decrease in fluorescence intensity and are moisture resistant. An object of the present invention is to provide a sulfide phosphor particle having a surface coating layer with significantly improved properties and a method for efficiently producing the same.

In order to achieve the above object, the inventors of the present invention provide a sulfide phosphor particle that absorbs excitation light and emits light, and a method for producing the same, and uses a silane organometallic compound on the surface of the sulfide phosphor particle to form a coating layer. As a result of earnest research on the formation method, the first step of obtaining sulfide phosphor particles (A) in which an aluminum organometallic compound is adsorbed as an underlayer on the surface under specific conditions and under specific conditions The second step of obtaining sulfide phosphor particles (B) having a silane organometallic compound film formed on the surface of the sulfide phosphor particles (A) obtained in the first step, and the sulfide obtained in the second step A method comprising a third step of subjecting the phosphor particles (B) to a heat treatment to obtain sulfide phosphor particles (C) having a coating layer formed of an amorphous inorganic compound film containing an organic component on the surface thereof. Is used, there is no decrease in fluorescence intensity and resistance It found that it is possible to sex to efficiently produce a sulfide phosphor particles having a significantly improved surface coating layer, thereby completing the present invention.
That is, in the formation of the coating layer, first, it is easy to bond to the surface of the sulfide particles, and after the coating is formed, the adsorption of the silane organic compound can be facilitated and the deterioration from the moisture for hydrolysis can be suppressed. An undercoat layer is formed using an aluminum organometallic compound, a hydrolyzed condensate of a silane organometallic compound is formed thereon, and these two-layer structures are used, and the resulting coating layer is then dried, In firing, it can withstand expansion due to a rapid hydrolysis / condensation reaction and a gas component generated by thermal decomposition of organic matter. Thus, even after the coating film is formed, sulfide phosphor particles having a surface coating layer that is not changed from the emission intensity and whose water resistance and moisture resistance are remarkably improved can be obtained.

That is, according to the first aspect of the present invention, there is provided a method for producing sulfide phosphor particles having a coating layer on the surface,
There is provided a method for producing sulfide phosphor particles characterized by including the following first to third steps.
First step: A solution prepared by adding sulfide phosphor particles to an organic solvent and subjecting to dispersion treatment is mixed with an aluminum organometallic compound, stirred and mixed, then subjected to vacuum filtration, and an underlayer is formed on the surface. As a result, sulfide phosphor particles (A) adsorbing an aluminum organometallic compound are obtained.
Second step: The sulfide phosphor particles (A) obtained in the first step are subjected to a dispersion treatment in an organic solvent, and then the silane organometallic compound forming the main layer of the coating layer and aluminum acting as a catalyst. Add organometallic compound and water for hydrolysis, stir and mix with heating, separate organic solvent, then subject to vacuum filtration to form silane organometallic compound film on its surface Thus obtained sulfide phosphor particles (B) are obtained.
Third step: The sulfide phosphor particles (B) obtained in the second step are subjected to heat treatment, the organic matter in the organometallic compound film is pyrolyzed, and the amorphous inorganic containing organic components on the surface thereof Sulfide phosphor particles (C) having a coating layer made of a compound film are obtained.

  According to a second aspect of the present invention, there is provided the method for producing sulfide phosphor particles according to the first aspect, wherein the organic solvent is ethanol or isopropyl alcohol.

  According to a third aspect of the present invention, in the first aspect, the aluminum organometallic compound is ethyl acetoacetate aluminum diisopropylate, and the silane organometallic compound is tetraethoxysilane. A method for producing sulfide phosphor particles is provided.

According to the fourth invention of the present invention, in the first invention, in the first step, the mixing ratio of the sulfide phosphor particles, the organic solvent and the aluminum organometallic compound is a mass ratio, and the sulfide fluorescence. Body particles: organic solvent = 1: 10 to 1:50, and sulfide phosphor particles: aluminum organometallic compound = 1: 0.1 to 1: 1, and the dispersion treatment, stirring and mixing, and vacuum filtration are respectively There is provided a method for producing sulfide phosphor particles characterized by satisfying the following requirements (a) to (c).
(A) The dispersion treatment is performed by ultrasonic dispersion treatment at 28 to 48 kHz for 10 to 30 minutes.
(B) The stirring and mixing is performed at a temperature of 18 to 60 ° C. for 0.5 to 5 hours.
(C) Vacuum filtration is performed at a vacuum degree of 0.05 to 0.1 MPa.

According to a fifth aspect of the present invention, in the first aspect, in the second step, the dispersion treatment, the stirring and mixing, and the vacuum filtration satisfy the following requirements (d) to (f), respectively. A method for producing sulfide phosphor particles is provided.
(D) Dispersion treatment is performed by mixing sulfide phosphor particles and an organic solvent in a mass ratio of sulfide phosphor particles: organic solvent = 1: 5 to 1:25, and performing ultrasonic dispersion treatment at 28 to 48 kHz. Run for 10-30 minutes, then heat at 40-70 ° C. under seal.
(E) Stirring and mixing are performed in a sealed state, silane organometallic compound, aluminum organometallic compound, and water in a mass ratio, sulfide phosphor particles: silane organometallic compound = 1: 10 to 1:20, sulfide fluorescence. Body particles: Aluminum organometallic compound = 1: 0.01 to 1: 0.03 and sulfide phosphor particles: Water = 1: 5 to 1:10 In a mixing ratio, then opened and then opened to 0.5 Stir for ~ 2 hours.
(F) Vacuum filtration is performed at a vacuum degree of 0.05 to 0.1 MPa.

  According to a sixth aspect of the present invention, in the first aspect, in the third step, the heat treatment is performed by heating in the atmosphere at a temperature of 200 to 400 ° C. for 0.5 to 2 hours. A method for producing the featured sulfide phosphor particles is provided.

  According to the seventh invention of the present invention, in any one of the first to sixth inventions, the sulfide phosphor particles include calcium (S) and europium (Eu) as a constituent element in addition to calcium. There is provided a method for producing sulfide phosphor particles, comprising at least one element selected from (Ca), strontium (Sr), and gallium (Ga).

According to an eighth aspect of the present invention, in the seventh aspect, the sulfide phosphor particle further has a composition formula of CaS: Eu, SrS: Eu, (Ca, Sr) S: Eu. Or a method for producing sulfide phosphor particles, comprising a compound phase represented by at least one selected from SrGa ₂ S ₄ : Eu.

According to a ninth aspect of the present invention, there is provided a sulfide phosphor particle that absorbs excitation light and emits light obtained by the production method of any one of the first to eighth aspects,
On the surface thereof, a base layer having a film thickness of 10 to 30 nm and containing aluminum (Al) and oxygen (O), a film thickness of 200 to 300 nm thereon, silicon (Si) and oxygen ( Provided is a sulfide phosphor particle having a two-layer structure composed of a main layer containing O) and having a coating layer composed of an amorphous inorganic compound film containing an organic component .

  The sulfide phosphor particle having the surface coating layer of the present invention has a two-layer structure composed of an underlayer containing aluminum and oxygen and a main layer containing silicon and oxygen on the organic layer and an organic component. Since it has a surface coating layer made of an amorphous inorganic compound film containing, as a sulfide phosphor particle used in light emitting devices such as LEDs, there is no decrease in fluorescence intensity and moisture resistance is remarkably improved It has been done. Moreover, since the manufacturing method can manufacture efficiently the sulfide fluorescent substance particle which has the said surface coating layer, the industrial value is very large.

Hereinafter, the sulfide phosphor particles having the surface coating layer of the present invention and the production method thereof will be described in detail.
1. A method for producing sulfide phosphor particles having a surface coating layer The method for producing sulfide phosphor particles having a surface coating layer according to the present invention is a method for producing sulfide phosphor particles having a coating layer on a surface, It includes the following first to third steps.
First step: A solution prepared by adding sulfide phosphor particles to an organic solvent and subjecting to dispersion treatment is mixed with an aluminum organometallic compound, stirred and mixed, then subjected to vacuum filtration, and an underlayer is formed on the surface. As a result, sulfide phosphor particles (A) adsorbing an aluminum organometallic compound are obtained.
Second step: The sulfide phosphor particles (A) obtained in the first step are subjected to a dispersion treatment in an organic solvent, and then the silane organometallic compound forming the main layer of the coating layer and aluminum acting as a catalyst. Add organometallic compound and water for hydrolysis, stir and mix with heating, separate organic solvent, then subject to vacuum filtration to form silane organometallic compound film on its surface Thus obtained sulfide phosphor particles (B) are obtained.
Third step: The sulfide phosphor particles (B) obtained in the second step are subjected to heat treatment, the organic matter in the organometallic compound film is pyrolyzed, and the amorphous inorganic containing organic components on the surface thereof Sulfide phosphor particles (C) having a coating layer made of a compound film are obtained.

  In the present invention, in the first step, an aluminum organic metal film is adsorbed on the surface of the sulfide phosphor particles used as a raw material to form a base layer, and in the second step, the base layer obtained in the first step is formed. Forming a silane organometallic compound film on the surface of the sulfide phosphor particles, and thermally decomposing an organic substance in the organometallic compound film in a third step, and an underlayer containing aluminum and oxygen; In addition, it has a two-layer structure composed of a main layer containing silicon and oxygen, and has an important technical significance in forming a coating layer made of an amorphous inorganic compound film containing an organic component. The technical significance will be described in detail in each step.

(1) Sulfide phosphor particles The sulfide phosphor particles used as a raw material in the above method are not particularly limited, and various sulfide phosphor particles can be used. In addition to sulfur (S) and europium (Eu), those containing at least one element selected from calcium (Ca), strontium (Sr) or gallium (Ga) are preferable. Furthermore, although the composition formula is not particularly limited, it is represented by at least one selected from CaS: Eu, SrS: Eu, (Ca, Sr) S: Eu, or SrGa ₂ S ₄ : Eu. Those having a compound phase are preferred.

  The average particle size is preferably 1 to 50 μm in D50 of the cumulative particle size distribution by the microtrack method. That is, when D50 exceeds 50 μm, the emission intensity decreases when used in a light emitting device such as an LED.

(2) 1st process The 1st process of the said method mix | blends an aluminum organometallic compound with the solution which added the sulfide fluorescent substance particle to the organic solvent, and was attached | subjected to the dispersion process, and attached to stirring, and then vacuumed. This is a step of obtaining sulfide phosphor particles (A) that are subjected to filtration and have an aluminum organometallic compound adsorbed on the surface as an underlayer.
Here, it is important to adsorb the aluminum organic metal film on the surface of the sulfide phosphor particles to form an underlayer. Therefore, instead of the above procedure, an organic solvent and an aluminum organometallic compound are mixed, and then the sulfide phosphor particles are added to the resulting solution, followed by stirring and mixing, then subjected to dispersion treatment, and finally stirred again. It can also be subjected to mixing.

  That is, in the conventional method of hydrolyzing and coating a silane organometallic compound such as alkoxysilane (for example, Patent Document 2), the bond at the interface between the sulfide phosphor particles and the hydrolyzed alkoxysilane is weak. It is difficult to form a film on the surface of the sulfide phosphor particles, and when the treatment temperature is increased to increase the reactivity of the alkoxysilane, the alkoxysilane volatilizes together with the organic solvent, and the amount of adhesion to the coating decreases. There was a problem related to reaction control. As a countermeasure, in the method of the present invention, it is effective to form an underlayer so that the silane organometallic compound is easily adsorbed on the particle surface. That is, by forming a base layer made of an aluminum organometallic film in advance on the surface of the sulfide phosphor particles, uniformity when coating the silane organometallic compound that becomes the main layer performed in the subsequent second step Will increase. This is because the active aluminum organometallic compound is immediately adsorbed on the particle surface, and the underlayer is uniformly formed. Thereby, the main layer formed on the base layer is formed firmly and uniformly, and a thick layer can be obtained. In addition, since this aluminum organometallic film has many hydroxyl groups, the bond with the main layer formed thereon becomes strong.

  However, in order to improve the adhesion at the interface between the sulfide phosphor particles and the underlayer, it is also important to remove the organic solvent once after the underlayer is formed. This removal is performed by separating the solvent by vacuum filtration. This removes the organic solvent that does not contribute to bonding at the particle interface, and strengthens the bonding between the particle surface and the aluminum organometallic compound. Thereafter, about half of the organic solvent used in the formation of the underlayer can be added and subjected to washing. This washing operation is effective when the concentration of the aluminum organometallic compound added is high, and is preferred because free aluminum organometallic compound is discharged by washing, so that aggregation and solidification after drying is eliminated. In addition, the separation of the organic solvent increases the adhesion and binding at the interface between the sulfide phosphor particles and the underlayer, so that the underlayer dissolves even if it is put in the organic solvent in the second step, or No peeling off. When the base layer is removed, the hydrolytic condensate of the silane organometallic compound as the main layer is not stably coated, and the moisture resistance does not increase.

  In addition, as an effect of forming the underlayer, it is possible to suppress deterioration from water for hydrolysis when the main layer is formed. That is, since the main layer is processed in a short time, it is heated at a low temperature when forming the coating. At this time, if there is no base layer, the sulfide is decomposed by water and heat, and the fluorescence characteristics are deteriorated.

The organic solvent used in the first step is not particularly limited, and is represented by the general formula: R ² OH (where R ² represents a monovalent hydrocarbon group having 1 to 6 carbon atoms). Although the alcohol solvent represented is used, ethanol or isopropyl alcohol is particularly preferable among them.

The aluminum organometallic compound used in the first step is not particularly limited, and is represented by the general formula: R ² OH (where R ² represents a monovalent hydrocarbon group having 1 to 6 carbon atoms). ) Which is compatible with the alcohol represented by the formula (1) and has a high adsorptive power to the surface of the oxide and sulfide phosphor particles, such as ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), Aluminum chelate compounds containing alkyl groups such as octyl acetoacetate aluminum diisoproprate, aluminum monoacetylacetonate bis (ethyl acetoacetate) are preferred. Of these, ethyl acetoacetate aluminum diisopropylate, which is highly compatible with ethanol and isopropyl alcohol, is more preferable.

  The aluminum chelate compound containing an alkyl group is adsorbed by hydrolyzing the alkyl group with a hydroxyl group on the particle surface or water in the solvent and hydrolyzing with the particle surface. Therefore, a very small amount of another organic metal can be added in order to promote the hydrolysis / condensation reaction. As the organic metal in this case, a silane organometallic compound and a zirconium organometallic compound are used. Examples of the silane organometallic compound include tetramethoxysilane or tetraethoxysilane, and examples of the zirconium organometallic compound include zirconium dibutoxybis (ethylacetoacetate). By adding a very small amount of at least one of these organic metals, the hydrolysis / condensation reaction of the aluminum chelate compound is further promoted, and the adsorption effect as the underlayer is enhanced.

  In the first step, the blending ratio of the sulfide phosphor particles, the organic solvent, and the aluminum organometallic compound is not particularly limited. For example, in the mass ratio, the sulfide phosphor particles: organic solvent = 1: 10 to 1:50 and sulfide phosphor particles: aluminum organometallic compound = 1: 0.1 to 1: 1 are preferable. When an aluminum organometallic compound is further blended, sulfide phosphor particles tend to aggregate when the organic solvent is separated.

In the first step, the dispersion treatment, stirring and mixing and vacuum filtration are not particularly limited, but it is preferable that the following requirements (a) to (c) are satisfied.
(A) The dispersion treatment is performed by ultrasonic dispersion treatment at 28 to 48 kHz for 10 to 30 minutes.
(B) The stirring and mixing is performed at a temperature of 18 to 60 ° C. for 0.5 to 5 hours.
(C) Vacuum filtration is performed at a vacuum degree of 0.05 to 0.1 MPa.

The dispersion treatment can be performed using an ultrasonic homogenizer having an ultrasonic transmitter of 28 to 48 kHz. Here, since the aggregation of the raw material particles is crushed by the ultrasonic treatment, it is possible to cover the entire particle with the coating in the formation of the underlayer. Furthermore, by subjecting the particle surface to ultrasonic treatment before coating, foreign substances or fine particles adhering to the surface that hinders coating can be eliminated, so that a more uniform underlayer can be formed.
The stirring and mixing is performed by a method using a stirring blade, a stirrer or the like, or a method using a homogenizer or the like.

  Moreover, the method of volatilizing and removing the organic solvent by heating can be employed for the separation of the organic solvent instead of the vacuum filtration. However, a vacuum filtration method is preferred for convenience. Note that it is not preferable to heat and dry at a temperature of 150 ° C. or higher after the separation of the organic solvent, because the adsorbed aluminum organometallic compound is denatured and the adsorptivity with the silane organometallic compound is adversely reduced in the subsequent steps.

  The thickness of the underlayer obtained in the first step is not particularly limited, and is sufficient if aggregation between particles and film peeling do not occur at the time of drying. In order to express it, the film thickness is desirably 10 nm or more, and particularly preferably 10 to 30 nm.

(3) Second Step The second step of the above method is a silane for subjecting the sulfide phosphor particles (A) obtained in the first step to a dispersion treatment in an organic solvent and then forming the main layer of the coating layer. Add organometallic compound, aluminum organometallic compound acting as catalyst, and water for hydrolysis, stir and mix with heating, separate organic solvent, followed by vacuum filtration, Sulfide phosphor particles (B) having a silane organometallic compound film formed on the surface are obtained.

  In the second step, the main layer is formed by bonding a hydrolyzed silane organometallic compound to the surface of the underlayer. Here, a film made of a polymer having high water resistance is formed by hydrolysis and condensation reaction of the silane organometallic compound. At this time, it is preferable to carry out by low temperature heating. As a result, the organic solvent is volatilized, and at the same time, the volatilization of the silane organometallic compound that becomes the main layer where condensation does not proceed is suppressed. In addition, by volatilizing the organic solvent, not only the condensation reaction is promoted but also the bonding at the particle interface is facilitated, so that the densification of the main layer and the increase in the film thickness are promoted.

In the second step, the silane organometallic compound undergoes a hydrolysis / condensation reaction due to the action of the aluminum organometallic compound and water, and the condensation proceeds gradually with the passage of time, and the molecular weight increases moderately. At this time, it is important to stop at an arbitrary degree of condensation. That is,
When the reaction proceeds too much, the coverage on the particle surface is lowered. On the other hand, if the reaction does not proceed, the film quality deteriorates due to volatilization during heat treatment and the moisture resistance is not improved.

In the second step, the aluminum organometallic compound is applied with a dispersant function for dispersing the sulfide phosphor particles it has and a function for promoting the condensation of the silane organometallic compound. It utilizes a catalytic function to activate the hydrolysis / condensation reaction.
In general, an acid-alkali catalyst has been used as a catalyst for the hydrolysis / condensation reaction of a silane organometallic compound. However, problems arise when an acid-alkali catalyst is used for sulfide phosphor particles. That is, when acetic acid or hydrochloric acid is added as an acid catalyst, for example, the compound phase represented by the composition formula: CaS: Eu or SrS: Eu reacts with the acid, and the deterioration of the particles or the dissolution of the particles themselves occurs over time. As the alkaline catalyst, ammonia water having no residue at the time of drying is used, but as described above, it is not formed as a coating on the particle surface. In addition, other organometallic catalysts such as organometallic compounds of tin and titanium are generally used, but aluminum organometallic compounds are most preferred from the standpoint of stability during the production of the coating material.

In the second step, it is important that the sulfide particles (A) on which the underlayer is formed are well dispersed in an organic solvent. That is, when the coating process is performed in the state of being agglomerated, the entire surface of the particles cannot be coated, and the moisture resistance is not improved.
The organic solvent used in the second step is not particularly limited, and is represented by the general formula: R ² OH (where R ² represents a monovalent hydrocarbon group having 1 to 6 carbon atoms). Although the alcohol solvent represented is used, ethanol or isopropyl alcohol is particularly preferable among them. For example, in the first step, vacuum filtration is performed after coating using isopropyl alcohol, and in the second step, the organic solvent is volatilized and removed by heating. Therefore, if ethanol having a low boiling point is used, the working time can be shortened.

The aluminum organometallic compound used in the second step is not particularly limited, and ethyl acetoacetate aluminum diisopropylate is preferable.
The water used in the second step is preferably ion-exchanged water having a conductivity of 4 μS / cm or less.

  The silane organometallic compound used in the second step is not particularly limited, and tetraethoxysilane is preferable from the viewpoint of stability, covering property, and film quality at the time of preparing the hydrolyzed condensate. The tetraethoxysilane is preferably monomeric. The hydrolysis condensate of tetraethoxysilane cannot be added. For example, if water and a catalyst necessary for hydrolysis are added to a mixture of tetraethoxysilane and an alcohol solvent in advance and left to stir at room temperature for several hours, a condensate can be obtained. However, the resulting condensate is a cloudy sol-like liquid, and even if this is used as a coating material, it becomes coated particles in which fine particles are deposited around the particles, or the fine particles aggregate without adsorbing on the particle surface. Thus, only coated particles which are precipitated and have poor moisture resistance can be obtained. For this reason, in the second step, a tetraethoxysilane monomer is added to the particles to be coated, and the coating is formed while undergoing a hydrolytic condensation reaction. As other silane organometallic compounds, tetramethoxysilane monomers can be used, but methanol is generated during the hydrolysis reaction, which is not preferable from the viewpoint of influence on the human body.

The dispersion treatment, stirring and mixing and vacuum filtration used in the second step are not particularly limited, and it is preferable that the following requirements (d) to (f) are satisfied.
(D) Dispersion treatment is performed by mixing sulfide phosphor particles and an organic solvent in a mass ratio of sulfide phosphor particles: organic solvent = 1: 5 to 1:25, and performing ultrasonic dispersion treatment at 28 to 48 kHz. Run for 10-30 minutes, then heat at 40-70 ° C. under seal.
(E) Stirring and mixing are performed in a sealed state, silane organometallic compound, aluminum organometallic compound, and water in a mass ratio, sulfide phosphor particles: silane organometallic compound = 1: 10 to 1:20, sulfide fluorescence. Body particles: Aluminum organometallic compound = 1: 0.01 to 1: 0.03 and sulfide phosphor particles: Water = 1: 5 to 1:10 In a mixing ratio, then opened and then opened to 0.5 Stir for ~ 2 hours.
(F) Vacuum filtration is performed at a vacuum degree of 0.05 to 0.1 MPa.

In the stirring and mixing, it is preferable that the container system is first sealed until all the solutions are added, and then all the solutions are dropped and then opened to remove the organic solvent. Here, it adds in the said mixture ratio in the organic solvent under sealing. That is, at this time, if the container is opened, the organic solvent is immediately volatilized and lost, and the liquid composition changes. In addition, although water and an aluminum organometallic compound may be added in the liquid heated directly, in order to suppress a rapid reaction, it is preferable to dilute with an organic solvent. For this reason, the organic solvent may be removed in advance for dilution. As the amount of the organic solvent for dilution, the same amount as that of water can be added. The dropping rate of these reaction solutions is preferably about 1 to 2 mL / min.
When the organic solvent is completely removed and dried, the particles are aggregated and are difficult to handle. Therefore, the removal of the organic solvent is terminated when the remaining amount becomes approximately 1/3, or when the liquid viscosity becomes 5 mPa · S or more, and then the organic solvent is removed by vacuum filtration under the above conditions. .

  The stirring and mixing is performed by a method using a stirring blade, a stirrer or the like, or a method using an ultrasonic homogenizer or the like.

  In the second step, not all of the silane organometallic compound is formed into a film, but a polymer formed as a polymer is deposited as a film, but a low molecular material with insufficient condensation is an organic solvent. It is removed together with volatilization. For this reason, temperature control during stirring is important, and the liquid temperature must be constantly monitored.

  The thickness of the silane organometallic compound film obtained in the second step is not particularly limited, and the film thickness is preferably 200 to 300 nm. That is, when the film thickness is less than 200 nm, sufficient water resistance cannot be obtained. On the other hand, if the film thickness exceeds 300 nm, it is difficult to obtain a thick film with good film quality.

(4) Third Step In the third step of the above method, the sulfide phosphor particles (B) obtained in the second step are subjected to heat treatment, the organic matter in the organometallic compound film is thermally decomposed, and the surface thereof This is a step of obtaining sulfide phosphor particles (C) in which a coating layer made of an amorphous inorganic compound film containing an organic component is formed. Thereby, the permeation | transmission of humidity can be suppressed more effectively and moisture resistance improves.

  The atmosphere of the heat treatment used in the third step is not particularly limited, and is performed in the air, in an inert gas, in a vacuum, or in a plurality of these atmospheres. That is, in order to mitigate the influence of oxidation in the atmosphere, it can be processed in vacuum in an inert gas with little oxygen. For example, after removing most of the organic substances by treating in the air in a low temperature region, a method of performing high temperature treatment using these oxygen-free atmospheres is employed.

  The temperature of the heat treatment used in the third step is not particularly limited and depends on the heat resistance of the sulfide phosphor particles, but is preferably 200 to 400 ° C, more preferably 200 to 350 ° C. preferable. That is, the higher the heating temperature, the stronger the film and the better the moisture resistance. However, sulfide phosphor particles tend to decompose at high temperatures when they come into contact with the atmosphere. For example, in a phosphor containing Eu, the temperature is When the temperature exceeds 400 ° C., Eu is oxidized in an atmosphere where oxygen exists, particularly in the air, and changes from divalent to trivalent. On the other hand, 200 ° C. or higher, which is the thermal decomposition temperature of aluminum or silane organometallic compound, is used.

  The time for the heat treatment used in the third step is not particularly limited. For example, when heating at 200 to 400 ° C. in the air, 0.5 to 2 hours is preferable. As a result, the organic material in the base layer made of an aluminum organometallic compound and the silane organometallic compound film is thermally decomposed and mineralized, resulting in, for example, some organic solvent components and an amorphous silane compound. In addition, an inorganic compound film containing an amorphous silicon inorganic compound containing an organic substance as a main component is formed.

2. Sulfide phosphor particles having a surface coating layer The sulfide phosphor particles having a surface coating layer of the present invention are sulfide phosphor particles that are obtained by the above-described production method and absorb excitation light to emit light. On the surface of the phosphor particles, a film thickness of 10 to 30 nm, an underlayer containing aluminum (Al) and oxygen (O), and a film thickness of 200 to 300 nm thereon, and silicon (Si) And a main layer containing oxygen (O), and having a coating layer made of an amorphous inorganic compound film containing an organic component.

  As the structure of the sulfide phosphor particles having the above surface coating layer, an aluminum organometallic compound that can be easily bonded to the surface of the sulfide particles and can suppress deterioration from moisture for hydrolysis after the coating is formed is used. As a sulfide phosphor particle used in a light-emitting element such as an LED, a surface coating layer having a two-layer structure in which a base layer is formed and a hydrolyzate of a silane organometallic compound is formed thereon. , The fluorescence intensity does not decrease and the moisture resistance is remarkably improved.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples. In addition, the evaluation method of the film thickness and water resistance (conductivity change and luminous intensity change rate) used by the Example and the comparative example is as follows.
(1) Evaluation of film thickness of coating layer: Particles are embedded in an epoxy resin, a cross section is processed after curing, and SEM observation is performed. Here, the dimension of the coating layer (n = 5) was measured from the obtained image, and the average film thickness was determined. At this time, since the contrast of the coating layer can be changed due to the difference in composition, it can be clearly observed in the secondary electron image and the reflected electron image. In addition, when the coating layer of the particle | grains obtained in the Example was analyzed by SEM-EDX, since the element of Si and O was detected, it was confirmed that the layer observed by shading was due to the coating.

(2) Evaluation of water resistance: As an evaluation of water resistance, particles were introduced into water to determine the change in conductivity. That is, in the case of sulfide phosphor particles having poor water resistance, components are eluted from the particle surface into water, and the conductivity increases with the immersion time. For example, for SrGa ₂ S ₄ : Eu particles, 0.1 g of particles was put into 100 mL of warm water at 80 ° C., and the change in conductivity after stirring for 20 minutes was measured. For SrS: Eu or CaS: Eu particles, 0.1 g of the particles was put into 100 mL of hot water at 25 ° C., and the change in conductivity after stirring for 20 minutes was measured. Further, the emission intensity before and after the coating treatment was measured, and the rate of change in emission intensity: [(initial intensity−intensity after 20 minutes of water immersion) / initial intensity] was determined. Incidentally, the excitation light at the time of measurement, a peak emission wavelength (SrGa ₂ S _4: Eu is 460 nm, SrS: Eu is 550 nm, and CaS: Eu is 590 nm) was used.

  Moreover, the organic solvent used by the Example and the comparative example used the molecular sieve 3A500g dried beforehand in 10 L of organic solvents, and used it after removing water. The water content in the IPA used in the examples of the present invention was 0.1 g / L with a Karl Fischer moisture meter.

Example 1
The following 1st-3rd processes were performed and the obtained sulfide fluorescent substance particle (C) was evaluated.
First step: Formation of an underlayer with an organometallic compound of aluminum 50 g of isopropyl alcohol (IPA: deer grade 1 manufactured by Kanto Chemical Co., Ltd.), ethyl acetoacetate aluminum diisopropylate (trade name, aluminum chelate ALCH, manufactured by Kawaken Fine Chemical Co., Ltd.) 2 g was added and mixed. 2 g of strontium thiogallate europium (SrGa ₂ S ₄ : Eu, 1000 ° C. synthesized, D50 = 10 μm) was added as sulfide phosphor particles to this mixed solution, and 10 μg at 28 kHz using an ultrasonic cleaner. Dispersion (1) was obtained by treatment for a minute. Next, the dispersion (1) was stirred and mixed at a temperature of 25 ° C. for 2 hours, and then vacuum filtered to obtain particles. Furthermore, 30 mL of IPA was poured into the particles after filtration, and vacuum filtration was performed again to collect sulfide phosphor particles (A).

Second Step: Formation of Coating Film of Silane Organometallic Compound The sulfide phosphor particles (A) obtained in the first step are put into 20 g of ethanol, sealed and heated with stirring, and the liquid temperature is set to 60. Controlled to ° C. Next, 30 g of tetraethoxysilane (manufactured by Kanto Chemical) was added to this liquid to obtain a dispersion liquid (2). Furthermore, a mixed solution composed of 10 g of ethanol, 10 g of water, and 0.02 g of ethyl acetoacetate aluminum diisopropylate (manufactured by Kawaken Fine Chemical Co., Ltd., trade name: aluminum chelate ALCH) was prepared in a separate container. Subsequently, while continuing to heat the dispersion (2), this mixed solution was dropped at a rate of 1 mL / min. After stirring and mixing for 0.5 hour, the container was opened and stirred for 1 hour. Was removed. When the amount of residual liquid reached 30 mL, heating was terminated, and after cooling, vacuum filtration was performed to recover sulfide phosphor particles (B).

Third step: calcination treatment The sulfide phosphor particles (B) obtained in the second step are dried by heating at a temperature of 110 ° C. for 1 hour, and then baked at a temperature of 200 ° C. for 1 hour to form a coating layer. Thus obtained sulfide phosphor particles (C) were obtained.
Then, the said sulfide fluorescent substance particle (C) was evaluated with the evaluation method of the said film thickness and water resistance (conductivity change and luminous intensity change rate). The results are shown in Table 1.

(Example 2)
In the first step, ethyl acetoacetate aluminum diisopropylate (manufactured by Kawaken Fine Chemical Co., Ltd., trade name: aluminum chelate ALCH) was added in an amount changed from 2 g to 1 g, and the dispersion was obtained by vacuum filtration. Except that IPA was poured into the particles and vacuum filtration was not performed again, the first to third steps were performed in the same manner as in Example 1 to obtain sulfide phosphor particles (C) having a coating layer formed thereon.
Then, the said sulfide fluorescent substance particle (C) was evaluated with the evaluation method of the said film thickness and water resistance (conductivity change and luminous intensity change rate). The results are shown in Table 1.

(Example 3)
In the first step, IPA was poured into the particles obtained by vacuum filtration of the dispersion and no vacuum filtration was performed again. In the second step, the liquid temperature was 40 ° C. A sulfide phosphor in which a coating layer was formed by carrying out the first to third steps in the same manner as in Example 1 except that the mixture was stirred for 1.5 hours after opening and the second step was repeated twice under the same conditions. Particles (C) were obtained.
Then, the said sulfide fluorescent substance particle (C) was evaluated with the evaluation method of the said film thickness and water resistance (conductivity change and luminous intensity change rate). The results are shown in Table 1.

Example 4
In the first step, the steps 1 to 3 are performed except that calcium sulfide europium (CaS: Eu, 900 ° C. composite, D50 = 2 μm) is used as the sulfide phosphor particle instead of strontium thiogallate europium. It carried out similarly to Example 1 and obtained the sulfide fluorescent substance particle (C) in which the coating layer was formed.
Then, the said sulfide fluorescent substance particle (C) was evaluated with the evaluation method of the said film thickness and water resistance (conductivity change and luminous intensity change rate). The results are shown in Table 1.

(Example 5)
In the first step, the first to third steps are performed except that strontium sulfide europium (SrS: Eu, 950 ° C. composite, D50 = 2 μm) is used as the sulfide phosphor particle instead of strontium thiogallate europium. It carried out similarly to Example 1 and obtained the sulfide fluorescent substance particle (C) in which the coating layer was formed.
Then, the said sulfide fluorescent substance particle (C) was evaluated with the evaluation method of the said film thickness and water resistance (conductivity change and luminous intensity change rate). The results are shown in Table 1.

(Example 6)
In the first step, ethyl acetoacetate aluminum diisopropylate (manufactured by Kawaken Fine Chemical Co., Ltd., trade name: aluminum chelate ALCH) was added in an amount changed from 2 g to 0.5 g, and the dispersion (1) was stirred and mixed. Except that the conditions were 1 hour at a temperature of 40 ° C., and in the second step, the liquid temperature was 65 ° C., and the container was stirred for 0.7 hours after opening the inside of the container. Three steps were performed in the same manner as in Example 1 to obtain sulfide phosphor particles (C) having a coating layer formed thereon.
Then, the said sulfide fluorescent substance particle (C) was evaluated with the evaluation method of the said film thickness and water resistance (conductivity change and luminous intensity change rate). The results are shown in Table 1.

(Comparative Example 1)
The sulfide phosphor particles were directly coated with tetraethoxysilane, and the resulting surface-coated particles were evaluated.
First, 2 g of strontium thiogallate europium (SrGa ₂ S ₄ : Eu, 1000 ° C. composite, D50 = 10 μm) is added as sulfide phosphor particles to 80 g of isopropyl alcohol (IPA: deer grade 1 manufactured by Kanto Chemical Co., Inc.). The mixture was stirred and mixed at a temperature of 25 ° C. for 2 hours to obtain a dispersion liquid (1).
Subsequently, the dispersion liquid (1) was sealed and heated with stirring, and the liquid temperature was controlled at 75 ° C. Subsequently, 30 g of tetraethoxysilane (manufactured by Kanto Chemical) was added to obtain a dispersion liquid (2). Further, 10 g of water was dropped into the dispersion liquid (2) at a rate of 1 mL / min, and the mixture was stirred and mixed for 1 hour and then cooled. Finally, the dispersion was vacuum filtered to recover the particles, heated and dried at 110 ° C. for 1 hour, and then fired at 200 ° C. for 1 hour to obtain surface-coated particles containing silicon and oxygen. .
Thereafter, the surface-coated particles were evaluated by an evaluation method of the film thickness and water resistance (conductivity change and emission intensity change rate). The results are shown in Table 1. In the above evaluation of the film thickness, the film thickness of the layer formed on the particle surface was partially 80 nm, but it was not a film that uniformly covered the entire periphery of the particle due to uncovered parts. It was.

(Comparative Example 2)
Silicon sulfide and oxygen were used in the same manner as in Comparative Example 1 except that calcium sulfide europium (CaS: Eu, 900 ° C. synthesized, D50 = 2 μm) was used as the sulfide phosphor particle instead of strontium thiogallate europium. Surface-coated particles containing were obtained.
Thereafter, the surface-coated particles were evaluated by an evaluation method of the film thickness and water resistance (conductivity change and emission intensity change rate). The results are shown in Table 1. In the above evaluation of the film thickness, the film thickness of the layer formed on the particle surface was 110 nm partially, but it is not a film that uniformly covers the entire periphery of the particle because there is an uncoated part. It was.

(Comparative Example 3)
The same procedure as in Comparative Example 1 was conducted except that strontium sulfide europium (SrS: Eu, 950 ° C. composite, D50 = 2 μm) was used as the sulfide phosphor particle instead of strontium thiogallate europium, and a dispersion ( 2) was obtained. Furthermore, when 10 g of water is dropped into the dispersion liquid (2) at a rate of 1 mL / min and stirring and mixing is continued, the color of the particle surface changes, and when stirring and mixing is performed for 0.2 hours, the particles are translucent. And dissolved in the dispersion.

(Comparative Example 4)
As the sulfide phosphor particles, strontium sulfide europium (SrS: Eu, 950 ° C. composite, D50 = 2 μm) was used instead of strontium thiogallate europium, and the liquid temperature was changed in the production of the dispersion liquid (2). A dispersion (2) was obtained in the same manner as in Comparative Example 1 except that the temperature was changed from 75 ° C to 25 ° C. Furthermore, when 10 g of water is dropped into the dispersion liquid (2) at a rate of 1 mL / min and stirring and mixing is continued, the color of the particle surface changes, and when stirring and mixing is performed for 0.5 hour, the particles are translucent. And dissolved in the dispersion.

(Comparative Example 5)
In the production of the dispersion liquid (2), except that the liquid temperature was changed from 75 ° C. to 25 ° C., it was carried out in the same manner as in Comparative Example 1 to obtain surface-coated particles containing silicon and oxygen.
Thereafter, the surface-coated particles were evaluated by an evaluation method of the film thickness and water resistance (conductivity change and emission intensity change rate). The results are shown in Table 1. In the evaluation of the film thickness, the layer formed on the particle surface could not be identified.

(Comparative Example 6)
Strontium thiogallate europium (SrGa ₂ S ₄ : Eu, 1000 ° C. synthesized, D50 = 10 μm) phosphor particles having no coating layer are heated and dried at 110 ° C. for 1 hour, and then at 200 ° C. for 1 hour. The surface-coated particles were then evaluated by a method for evaluating the film thickness and water resistance (conductivity change and emission intensity change rate). The results are shown in Table 1.

(Comparative Example 7)
Calcium sulfide europium (CaS: Eu, 900 ° C. composite, D50 = 2 μm) phosphor particles not having a coating layer are heated and dried at a temperature of 110 ° C. for 1 hour, and then calcined at a temperature of 200 ° C. for 1 hour. Thereafter, the surface-coated particles were evaluated by an evaluation method of the film thickness and water resistance (conductivity change and emission intensity change rate). The results are shown in Table 1.

(Comparative Example 8)
Strontium sulfide europium (SrS: Eu, 950 ° C. synthesized, D50 = 2 μm) phosphor particles having no coating layer were heated and dried at a temperature of 110 ° C. for 1 hour, and then baked at a temperature of 200 ° C. for 1 hour. Thereafter, the surface-coated particles were evaluated by an evaluation method of the film thickness and water resistance (conductivity change and emission intensity change rate). The results are shown in Table 1.

From Table 1, in Examples 1-6, in the method for producing sulfide phosphor particles having a surface coating layer, a sulfide phosphor in which an aluminum organometallic compound is adsorbed as an underlayer on the surface under predetermined conditions. A first step of obtaining particles (A), a second step of obtaining sulfide phosphor particles (B) in which a silane organometallic compound film is formed on the surface of sulfide phosphor particles (A) under predetermined conditions, A third step of subjecting the sulfide phosphor particles (B) obtained in the second step to heat treatment to obtain sulfide phosphor particles (C) having a coating layer made of an inorganic compound film containing an organic substance on the surface thereof. Since the method was carried out according to the method of the present invention, an underlayer having a film thickness of 10 to 30 nm and containing aluminum and oxygen on the surface of the sulfide phosphor particles, and a film thickness of 200 nm thereon. ~ 300 nm and silicon and A two-layer structure composed of a main layer containing element and a coating layer made of an amorphous inorganic compound film containing an organic component is formed, the decrease in fluorescence intensity is small, and the moisture resistance is remarkably improved. It turns out that the sulfide fluorescent substance particle suitable for light emitting elements, such as LED which has the surface coating layer made, can be manufactured efficiently.
On the other hand, in Comparative Examples 1 to 5, in forming the underlayer with the aluminum organometallic compound, these conditions are not met, so that a satisfactory result cannot be obtained with the change in conductivity or the change in emission intensity. I understand. On the other hand, in Comparative Examples 6 to 8 where no coating layer is formed, it can be seen that satisfactory results cannot be obtained with water resistance (conductivity change and emission intensity change rate).

  As is clear from the above, the sulfide phosphor particles having the surface coating layer of the present invention and the method for producing the same are the sulfide phosphor having the surface coating layer in which the fluorescence intensity is not reduced and the moisture resistance is remarkably improved. Since the particles can be produced efficiently, it is particularly suitable as a method for forming a surface coating layer of sulfide phosphor particles used in the field of light emitting devices such as LEDs.

Claims (9)

A method for producing sulfide phosphor particles having a coating layer on a surface,
The manufacturing method of the sulfide fluorescent substance particle characterized by including the following 1st-3rd processes.
First step: A solution prepared by adding sulfide phosphor particles to an organic solvent and subjecting to dispersion treatment is mixed with an aluminum organometallic compound, stirred and mixed, then subjected to vacuum filtration, and an underlayer is formed on the surface. As a result, sulfide phosphor particles (A) adsorbing an aluminum organometallic compound are obtained.
Second step: The sulfide phosphor particles (A) obtained in the first step are subjected to a dispersion treatment in an organic solvent, and then the silane organometallic compound forming the main layer of the coating layer and aluminum acting as a catalyst. Add organometallic compound and water for hydrolysis, stir and mix with heating, separate organic solvent, then subject to vacuum filtration to form silane organometallic compound film on its surface Thus obtained sulfide phosphor particles (B) are obtained.
Third step: The sulfide phosphor particles (B) obtained in the second step are subjected to heat treatment, the organic matter in the organometallic compound film is pyrolyzed, and the amorphous inorganic containing organic components on the surface thereof Sulfide phosphor particles (C) having a coating layer made of a compound film are obtained.   The method for producing sulfide phosphor particles according to claim 1, wherein the organic solvent is ethanol or isopropyl alcohol.   The method for producing sulfide phosphor particles according to claim 1, wherein the aluminum organometallic compound is ethyl acetoacetate aluminum diisopropylate, and the silane organometallic compound is tetraethoxysilane. In the first step, the mixing ratio of the sulfide phosphor particles, the organic solvent and the aluminum organometallic compound is a mass ratio, sulfide phosphor particles: organic solvent = 1: 10 to 1:50, and the sulfide phosphor. Particle: Aluminum organometallic compound = 1: 0.1 to 1: 1, and the dispersion treatment, stirring and mixing, and vacuum filtration satisfy the following requirements (a) to (c), respectively: The manufacturing method of the sulfide fluorescent substance particle of Claim 1.
(A) The dispersion treatment is performed by ultrasonic dispersion treatment at 28 to 48 kHz for 10 to 30 minutes.
(B) The stirring and mixing is performed at a temperature of 18 to 60 ° C. for 0.5 to 5 hours.
(C) Vacuum filtration is performed at a vacuum degree of 0.05 to 0.1 MPa. In the said 2nd process, the said dispersion process, stirring mixing, and vacuum filtration satisfy the following requirements (d)-(f), respectively, The manufacture of the sulfide fluorescent substance particle of Claim 1 characterized by the above-mentioned. Method.
(D) Dispersion treatment is performed by mixing sulfide phosphor particles and an organic solvent in a mass ratio of sulfide phosphor particles: organic solvent = 1: 5 to 1:25, and performing ultrasonic dispersion treatment at 28 to 48 kHz. Run for 10-30 minutes, then heat at 40-70 ° C. under seal.
(E) Stirring and mixing are performed in a sealed state, silane organometallic compound, aluminum organometallic compound, and water in a mass ratio, sulfide phosphor particles: silane organometallic compound = 1: 10 to 1:20, sulfide fluorescence. Body particles: Aluminum organometallic compound = 1: 0.01 to 1: 0.03 and sulfide phosphor particles: Water = 1: 5 to 1:10 In a mixing ratio, then opened and then opened to 0.5 Stir for ~ 2 hours.
(F) Vacuum filtration is performed at a vacuum degree of 0.05 to 0.1 MPa.   2. The method for producing sulfide phosphor particles according to claim 1, wherein in the third step, the heat treatment is performed in the atmosphere at a temperature of 200 to 400 ° C. for 0.5 to 2 hours.   The sulfide phosphor particles contain at least one element selected from calcium (Ca), strontium (Sr), and gallium (Ga) in addition to sulfur (S) and europium (Eu) as constituent elements. The method for producing sulfide phosphor particles according to claim 1, wherein: The sulfide phosphor particles further have a compositional formula represented by at least one selected from CaS: Eu, SrS: Eu, (Ca, Sr) S: Eu, or SrGa ₂ S ₄ : Eu. The method for producing sulfide phosphor particles according to claim 7, comprising a phase. A sulfide phosphor particle that absorbs excitation light and emits light obtained by the production method according to claim 1,
On the surface thereof, a base layer having a film thickness of 10 to 30 nm and containing aluminum (Al) and oxygen (O), a film thickness of 200 to 300 nm thereon, silicon (Si) and oxygen ( A sulfide phosphor particle having a two-layer structure composed of a main layer containing O), and having a coating layer made of an amorphous inorganic compound film containing an organic component.