KR20210080427A - Surface-coated phosphor particles, composites and light emitting devices - Google Patents

Abstract

The surface-coated phosphor particles of a certain aspect include phosphor particles containing oxynitride phosphors or nitride phosphors, and at least one element selected from the group consisting of aluminum, titanium, zirconium, yttrium and hafnium, which is provided on the surface of the phosphor particles. A coating layer made of a metal hydroxide or metal oxide containing The surface-coated phosphor particles have a hot water extraction electrical conductivity index ΔΩ defined below of 2.0 mS/m or less.
(Calculation method of hot water extraction electrical conductivity index)
(1) measuring the electric conductivity Ω ₀ of the ion-exchanged water of 25 ℃. (2) the ion exchange can 30ml and dispersing said surface-coated phosphor particles 1g, and then heated at 150 ℃ 16 sigan it in pressure-resistant container, electrical conductivity in the added ion-exchanged water 20ml, and cooled to 25 ℃ state Ω ₁ measure (3) _{Let the difference ΔΩ between electrical conductivity Ω 1} and electrical conductivity Ω ₀ (= electrical conductivity Ω ₁ -electric conductivity Ω ₀ ) be the hot water extraction electrical conductivity index ΔΩ.

Description

Surface-coated phosphor particles, composites and light emitting devices

The present invention relates to surface-coated phosphor particles, composites and light emitting devices.

In recent years, development of a light-emitting device combining a semiconductor light-emitting element such as an LED and a phosphor that absorbs a part of the light from the semiconductor light-emitting element, converts the absorbed light into wavelength-converted light of a long wavelength, and emits light is progressing. As the phosphor, a nitride phosphor or an oxynitride phosphor having a relatively stable crystal structure is attracting attention.

In Patent Document 1, in order to improve the luminance of the β-sialon phosphor, it is disclosed that the surface of the β-sialon phosphor is coated with a metal hydroxide.

Patent Document 2 discloses, as a prior art, that the surface of phosphor particles is coated with a glass material for the purpose of suppressing hydrolysis of phosphor containing sulfide by reaction with moisture in the air. And, after pointing out the effect of the film on the dispersibility of the phosphor particles to the sealing material, in order to improve the dispersibility of the phosphor to the sealing material, a method of coating the surface of the phosphor particles with a coating material particle containing a metal oxide is disclosed. .

In Patent Document 3, in order to improve the gas barrier properties of the coating layer provided on the surface of the phosphor particles, the glass powder adhering to the surface of the phosphor particles is melted by heating to form a continuous film on the surface of the phosphor particles. has been

Japanese Patent Laid-Open No. 2014-197635 Japanese Patent Laid-Open No. 2008-291251 Japanese Patent Laid-Open No. 2009-13186

The inventors have investigated the characteristics of a light emitting device in which a composite in which a phosphor is sealed with a sealing material is inserted together with an LED, and the inventors have found that the light emission intensity decreases slightly with the passage of time. As a result of examining the cause of this phenomenon, when moisture that has moved through the sealing material comes into contact with the phosphor, the metal component in the phosphor is ionized and eluted in water, and the crystal structure of the phosphor gradually changes, so that the wavelength conversion efficiency of the phosphor is lowered. It has been found that this leads to a decrease in the light emission intensity of the light emitting device.

According to the present invention, phosphor particles including oxynitride phosphors or nitride phosphors, and metals provided on the surface of the phosphor particles and containing at least one element selected from the group consisting of aluminum, titanium, zirconium, yttrium and hafnium There is provided a surface-coated phosphor particle having a coating layer made of a hydroxide or a metal oxide and having a hot water extraction electrical conductivity index ?? defined below of 2.0 mS/m or less.

(Calculation method of hot water extraction electrical conductivity index)

(1) measuring the electric conductivity Ω ₀ of the ion-exchanged water of 25 ℃.

(2) 1 g of the surface-coated phosphor particles were dispersed in 30 ml of the ion-exchanged water, put in a pressure-resistant container, and heated at 150° C. for 16 hours, after which 20 ml of ion-exchanged water was added and cooled to 25° C. Electrical conductivity Ω ₁ measure

(3) _{Let the difference ΔΩ between electrical conductivity Ω 1} and electrical conductivity Ω ₀ (= electrical conductivity Ω ₁ -electric conductivity Ω ₀ ) be the hot water extraction electrical conductivity index ΔΩ.

Further, according to the present invention, there is provided a composite comprising the above-described surface-coated phosphor particles and a sealing material for sealing the surface-coated phosphor particles.

Further, according to the present invention, there is provided a light emitting device comprising a light emitting element that emits excitation light and the above-described complex for converting the wavelength of the excitation light.

According to the present invention, it is possible to suppress the metal component constituting the phosphor particles from eluting to moisture.

The above object and other objects, features, and advantages will be further clarified by the preferred embodiment described below and the accompanying drawings.
1 is a schematic cross-sectional view showing the structure of a light emitting device according to an embodiment.
2 is an SEM image of the surface-coated phosphor particles of Example 1. FIG.
3 is an SEM image of the surface-coated phosphor particles of Example 2. FIG.
4 is an SEM image of the phosphor particles of Comparative Example 1.

As a result of the inventors earnestly examining the technique for suppressing the elution of metal components constituting the phosphor particles as ions in water, it is important to highly control the shape of the coating layer formed on the surface of the phosphor particles, and in particular, It found out selecting the material to comprise, and came to completion of this invention. EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail.

(Surface-coated phosphor particles)

The surface-coated fluorescent substance particle which concerns on embodiment is equipped with fluorescent substance particle and the coating layer provided on the surface of the said fluorescent substance particle. Hereinafter, each structure of the surface-coated fluorescent substance particle of this embodiment is demonstrated.

(Phosphor particle)

The phosphor particles include an oxynitride phosphor or a nitride phosphor.

Examples of the oxynitride phosphor include Eu-containing α-sialon phosphors, Eu-containing β-sialon phosphors, and the like.

The α-sialon phosphor containing Eu is represented by the general formula: M _x Eu _y Si _12-(m+n) Al _(m+n) O _n N _16-n . In the above general formula, M is at least one element containing at least Ca selected from the group consisting of Li, Mg, Ca, Y and lanthanide elements (except for La and Ce), and the valence of M is When a is defined as ax+2y=m, x is 0<x≤1.5, 0.3≤m<4.5, 0<n<2.25.

A β-sialon phosphor containing Eu is a β-sialon represented by the general formula: Si _6-z Al _z O _z N _8-z (z=0.005 to 1) as a luminescent center of divalent europium (Eu ^{2 ). It} is a phosphor employing + ).

Examples of the nitride phosphor include a CASN phosphor containing Eu, a SCASN phosphor containing Eu, and the like.

The CASN phosphor containing Eu is, for example, represented by the formula CaAlSiN ₃ :Eu ²⁺ , using Eu ²⁺ as an activator, and refers to a red phosphor having a crystal containing alkaline earth silicide as a matrix. In addition, in the definition of the CASN fluorescent substance containing Eu in this specification, the SCASN fluorescent substance containing Eu is excluded.

A SCASN phosphor containing Eu is, for example, a red phosphor represented by the _{formula (Sr,Ca)AlSiN 3} :Eu ^{2+ , Eu 2+} as an activator, and a crystal containing alkaline earth silicide as a matrix. say

It is preferable that the phosphor particles of the present embodiment contain the above-mentioned α-sialon phosphor containing Eu, β-sialon phosphor containing Eu, CASN phosphor containing Eu, or SCASN phosphor containing Eu. .

In addition, the particle diameter of a phosphor particle is not specifically limited, The dispersibility with respect to the sealing material mentioned later and a desired wavelength conversion efficiency are adjusted suitably so that it may be acquired.

(coating layer)

In the present embodiment, a coating layer made of a metal hydroxide or metal oxide containing at least one element selected from the group consisting of aluminum, titanium, zirconium, yttrium and hafnium is provided on the surface of the phosphor particles. The metal hydroxide or metal oxide is excellent in transparency and stability, and among them, aluminum hydroxide or aluminum oxide is preferably used from the viewpoint of moisture barrier properties, cost suppression properties, and coating properties to phosphor particles.

The coating layer may be an aggregate formed by aggregation of a plurality of particles containing a metal hydroxide or metal oxide, but is preferably a continuous coating layer made of metal hydroxide or metal oxide and continuously covering the phosphor particles. Here, the continuous coating layer is a layered structure in which a metal hydroxide or a metal oxide becomes a continuous film, and has a structure different from the aggregate formed by densely aggregating a plurality of particles as in the invention described in Patent Document 2. The continuous coating layer may have a concave-convex structure in which a large number of non-penetrating concave portions were formed.

It is preferable that it is 50 % or more, and, as for the surface coverage of the fluorescent substance particle by a coating layer, it is more preferable that it is 70 % or more. By making the surface coverage by a coating layer as mentioned above, the quantity which the metal component of a fluorescent substance particle elutes as an ion can be suppressed further. Moreover, it is preferable that a coating layer coat|covers the whole surface of a fluorescent substance particle.

The surface coverage by the coating layer can be evaluated by X-ray photoelectron spectroscopy (XPS) measurement. Specifically, by XPS measurement, the content of Si on the surface of the phosphor particle (atm%: atom), which is contained in the phosphor particles and is not contained in the metal hydroxide or metal oxide constituting the coating layer, is Si. percentage) is obtained. Let A1 be the content rate of Si in the phosphor particles that are not subjected to the surface treatment described later and do not have coating with a metal hydroxide or metal oxide, and the content of Si in the phosphor particles that are the object of calculation of the surface coverage ratio When it is set as A2, the surface coverage by a coating layer is computable by the following formula|equation.

Surface coverage (%) = (A1-A2)/A1 x 100

0.01 micrometer or more is preferable and, as for the minimum of the thickness of a coating layer, 0.1 micrometer or more is more preferable. Moreover, 10 micrometers or less are preferable and, as for the upper limit of the thickness of a coating layer, 5 micrometers or less are more preferable. By making the thickness of a coating layer into 0.01 micrometer or more, the quantity which the metal component contained in fluorescent substance particle elutes as an ion can be suppressed further. Moreover, by making the thickness of a coating layer into 10 micrometers or less, the fall of the wavelength conversion efficiency of surface-coated fluorescent substance particle|grains can be suppressed.

(Hot Water Extraction Electrical Conductivity Index)

The surface-coated phosphor particles of the present embodiment have a hot water extraction electrical conductivity index ΔΩ defined below of 2.0 mS/m or less.

(Calculation method of hot water extraction electrical conductivity index)

(1) measuring the electric conductivity Ω ₀ of the ion-exchanged water of 25 ℃.

(2) 1 g of the surface-coated phosphor particles are dispersed in 30 ml of the ion-exchanged water using a dispersing device such as an ultrasonic disperser, put in a pressure-resistant container, heated at 150° C. for 16 hours, 20 ml of ion-exchanged water is added, Measure the _{electrical conductivity Ω 1} in the cooled state.

(3) _{Let the difference ΔΩ between electrical conductivity Ω 1} and electrical conductivity Ω ₀ (= electrical conductivity Ω ₁ -electric conductivity Ω ₀ ) be the hot water extraction electrical conductivity index ΔΩ.

The hot water extraction electrical conductivity index becomes an index indicating that the amount of metal ions eluted from the phosphor particles into water is small, so that the value is small.

(Method for producing surface-coated phosphor particles)

As an example of a method for producing a surface-coated phosphor particle having a coating layer made of a metal oxide, (1) a step of forming a coating layer with a material (particles, etc.) containing a metal hydroxide on the surface of the phosphor particle; (2) heating A manufacturing method including the step of converting a metal hydroxide into a metal oxide and converting a coating layer into a continuous coating layer by performing treatment to obtain surface-coated phosphor particles having a continuous coating layer containing a metal oxide is mentioned. In this manufacturing method, it becomes important to make the coating layer by the particle|grains containing a metal hydroxide into a precise|minute coating|cover so that it can convert into a continuous coating layer by heat processing.

As a manufacturing method of such a surface-coated fluorescent substance particle, below, three examples of manufacturing method examples 1-3 are given and demonstrated.

[Production Method Example 1]

The manufacturing method example 1 has a slurry preparation process, a stirring process, a pH adjustment process, a stirring/washing/filtration process, a drying process, and a heating process. The detail of each process is demonstrated below.

(Slurry preparation process)

Phosphor powder, ion-exchange water, and a substance containing metal hydroxide are mixed in appropriate amounts, respectively, to prepare a phosphor-containing slurry. The pH of the slurry obtained here is preferably within a range in which both the surface potential of the phosphor particles and the surface potential of the substance containing metal hydroxide take positive values. Each surface potential of a substance containing a phosphor particle and a metal hydroxide can be measured by, for example, a zeta potential measuring device. In addition, when aluminum hydroxide is used as a substance containing a metal hydroxide, it can be used in the form of aluminum hydroxide in a sol state (it may be customarily called alumina sol) or aluminum hydroxide aqueous solution.

(stirring process)

The slurry obtained in the slurry preparation step is stirred using a stirring means such as a stirrer or a stirring device so that the substance containing the phosphor powder and the metal hydroxide is sufficiently dispersed.

(pH adjustment process)

At a pH adjustment process, it adjusts so that pH may become 9 or more by dripping an alkali agent to the obtained slurry at a predetermined|prescribed dropping speed|rate. As an alkali agent, _{alkaline aqueous solutions, such as NH 3} aqueous solution and NaOH aqueous solution, are mentioned. In the process of increasing the pH value by the addition of the alkali agent, the surface potential of the material containing the metal hydroxide becomes positive, and the surface potential of the phosphor particles is added. Thereby, it becomes easy to densely adhere the substance containing a metal hydroxide to the surface of a phosphor particle.

Specifically, when β-sialon phosphor particles are used as the phosphor particles and alumina sol is used as the material containing metal hydroxide, the surface potential of aluminum hydroxide becomes positive when the pH is 6.5 or higher, and the β-sialon phosphor is The surface potential of the particle is added. Thereby, since the electrostatic attraction acts between both, the substance containing aluminum hydroxide becomes easy to adhere closely to the surface of the β-sialon phosphor particle.

In addition, in the pH adjustment step, when an alkaline aqueous solution is used as the alkali agent, the thickness and surface coating of a substance containing a metal hydroxide adhering to the surface of the phosphor particles by adjusting the concentration, the dropping rate, and the dropping time of the alkaline aqueous solution. rate can be controlled.

(stirring, washing, filtration process)

The slurry obtained by the said pH adjustment process is stirred using stirring means, such as a stirrer, so that fluorescent substance particle may be fully disperse|distributed, and washing|cleaning liquid, such as ion-exchange water, is used for washing|cleaning. Thereafter, the phosphor powder (phosphor particles coated with a substance containing a metal hydroxide) is taken out by filtration means such as suction filtration.

(drying process)

Heat treatment for a predetermined time is performed so that the obtained phosphor powder is sufficiently dried to obtain a phosphor powder comprising a plurality of phosphor particles whose surfaces are densely coated with a substance containing a metal hydroxide.

(heating process)

By subjecting the obtained phosphor powder to heat treatment, the layer containing the metal hydroxide that densely coats the surface of the phosphor particles is oxidized to change to a metal oxide, and a continuous film-like form called a continuous coating layer composed of metal oxide is obtained. creates The temperature at the time of heating the phosphor powder is preferably 500°C or more and 1000°C or less, and in particular, when an alumina sol is used as a substance containing a metal hydroxide, the heating temperature is preferably 500°C or more and 600°C or less. Do. By the above process, the surface-coated phosphor particle|grains in which the continuous coating layer comprised from the metal oxide was formed on the surface of phosphor particle|grains is manufactured.

[Production Method Example 2]

The manufacturing method example 2 has a slurry preparation process, a stirring process, a stirring/washing/filtration process, a drying process, and a heating process. In the manufacturing method example 1, although the alkali agent was added and pH adjusted after the stirring process, in the manufacturing method example 2, an alkali agent is added and pH is adjusted in the slurry preparation process.

As in Production Method Example 1, if an alkali agent is added after the stirring step to adjust the pH, the coating layer made of a substance containing a metal hydroxide can be made a more dense coating layer. It is also possible to adjust the rate at which the alkali agent is added, whereby it is also possible to further improve the compactness of the coating. By setting it as such a dense coating layer, a continuous coating layer can be obtained stably by subsequent heat processing.

On the other hand, like the manufacturing method example 2, if pH is adjusted in a slurry preparation process, shortening of a manufacturing process can be aimed at.

[Production Method Example 3]

The manufacturing method example 3 has a slurry preparation process, a stirring process, a pH adjustment process, a stirring/washing/filtration process, a drying process, and a heating process. The detail of each process is demonstrated below.

In Production Method Example 1 and Production Method Example 2, a material containing a metal hydroxide is used as a starting material for the continuous coating layer. In Production Method Example 3, a precursor of a metal hydroxide is used as a starting material for the continuous coating layer.

(Slurry preparation process)

In this example, the phosphor powder, ion-exchanged water, and the metal hydroxide precursor are mixed in appropriate amounts to prepare a phosphor-containing slurry. When the metal hydroxide is aluminum hydroxide, Na aluminate is used as a precursor thereof. The slurry obtained is usually strongly alkaline, and specifically, pH 12 or more is preferable and pH 13 or more is more preferable. A metal hydroxide is precipitated by adding acids, such as hydrochloric acid and sulfuric acid, to this slurry. Thereby, the fluorescent substance containing slurry containing fluorescent substance powder, ion-exchange water, and a metal hydroxide is obtained. The pH of the phosphor-containing slurry obtained here is within a range in which both the surface potential of the phosphor particles and the surface potential of the metal hydroxide take negative values, and specifically, pH 11 or more is preferable, and pH 12 or more is more preferable.

(stirring process)

The slurry obtained in the slurry preparation process is stirred using stirring means, such as a stirrer, and a stirring apparatus so that a phosphor powder and a metal hydroxide may fully disperse|distribute.

(pH adjustment process)

At a pH adjustment process, by dripping acids, such as hydrochloric acid and a sulfuric acid, to the obtained slurry at a predetermined|prescribed dropping rate, it adjusts so that pH may become 9 or less. In the process where the pH value is lowered by the addition of an acid, among the surface potential of the metal hydroxide and the surface potential of the phosphor particles, one of the surface potentials becomes positive and the other surface potential is added to the surface of the phosphor particles. The metal hydroxide tends to be densely adhered.

Specifically, when β-sialon phosphor particles are used as phosphor particles and aluminum hydroxide is precipitated from a slurry containing Na aluminate, the surface potential of aluminum hydroxide becomes positive at a pH of 10 or less, and between β-type The surface potential of the Alon phosphor particles is added. Thereby, since the electrostatic attraction acts between both, aluminum hydroxide becomes easy to adhere closely to the surface of the β-sialon phosphor particle.

Moreover, in a pH adjustment process, the thickness and surface coverage of the metal hydroxide adhering to the surface of a phosphor particle can be controlled by adjusting the density|concentration of the acid dripped at the slurry, a dripping rate, and a dripping time.

After pH adjustment, similarly to Production Method Example 1, a continuous coating layer composed of a metal oxide is formed on the surface of the phosphor particles by performing a stirring step, a pH adjustment step, a stirring/washing/filtration step, a drying step, and a heating step. Phosphor particles are prepared.

In addition, in the manufacturing method example 3, the stirring process is implemented after addition of the acid in the slurry preparation process (the process of precipitating a metal hydroxide from a precursor substance), and also acid is added and pH is adjusted. As a method different from this, the slurry preparation process and the stirring process are performed in parallel, and an acid is continuously added from the slurry preparation process to adjust the pH, so that one of the surface potential of the metal hydroxide and the surface potential of the phosphor particles is the surface potential. may be positive, and the other surface potential may be negative.

Here, for example, it is possible to control the hot water extraction electrical conductivity index by appropriately selecting the type and amount of the metal oxide, a method for attaching the metal oxide to the surface of the phosphor particles, and the like. Among these, for example, pH adjustment conditions for densely adhering a material containing a metal hydroxide to the surface of the phosphor particles, for converting a material containing a metal hydroxide densely adhering to the surface of the phosphor particles into a metal oxide Heating conditions etc. are mentioned as a factor for making the said hot water extraction electrical conductivity index into a desired numerical range.

According to the surface-coated phosphor particles of this embodiment, by forming a coating layer composed of a metal oxide on the surface of the phosphor particles so that the hot water extraction electrical conductivity index ΔΩ is 2.0 mS/m or less, moisture around the surface-coated phosphor particles In the presence of this, the penetration of the moisture into the inside of the phosphor particles is suppressed. As a result of this, the amount of ions eluted by water decreases, and deterioration of the phosphor particles is suppressed.

(light emitting device)

1 is a schematic cross-sectional view showing a structure of a light emitting device according to an embodiment. As shown in FIG. 1 , the light emitting device 10 includes a light emitting element 20 , a heat sink 30 , a case 40 , a first lead frame 50 , a second lead frame 60 , and a bonding wire. 70 , a bonding wire 72 , and a composite 80 .

The light emitting element 20 is mounted on a predetermined area on the upper surface of the heat sink 30 . By mounting the light emitting element 20 on the heat sink 30 , heat dissipation of the light emitting element 20 can be improved. In addition, instead of the heat sink 30, you may use the board|substrate for packages.

The light emitting element 20 is a semiconductor element that emits excitation light. As the light emitting element 20, for example, an LED chip which generates light having a wavelength of 300 nm or more and 500 nm or less corresponding to near-ultraviolet or blue light can be used. One electrode (not shown) disposed on the upper surface side of the light emitting element 20 is connected to the surface of the first lead frame 50 via a bonding wire 70 such as a gold wire. In addition, the other electrode (not shown) formed on the upper surface of the light emitting element 20 is connected to the surface of the second lead frame 60 via a bonding wire 72 such as a gold wire.

The case 40 is formed with a substantially funnel-shaped recess in which the hole diameter gradually expands upward from the bottom surface. The light emitting element 20 is provided on the bottom surface of the concave portion. The wall surface of the concave portion surrounding the light emitting element 20 serves as a reflector.

The composite 80 is filled in the concave portion where the wall surface is formed by the case 40 . The composite 80 is a wavelength conversion member that increases the wavelength of the excitation light emitted from the light emitting element 20 . As the composite 80, the composite of the present embodiment is used, and the surface-coated phosphor particles 82 of the present embodiment are dispersed in a sealing material 84 such as resin. The light emitting device 10 emits a mixed color of the light from the light emitting element 20 and the light generated from the surface-coated phosphor particles 82 excited by absorbing the light from the light emitting element 20 . The light emitting device 10 preferably emits white light by mixing the light from the light emitting element 20 and the light generated from the surface-coated phosphor particles 82 .

In the light emitting device 10 of the present embodiment, as described above, the surface-coated phosphor particles 82 having a hot-water extraction electrical conductivity index ΔΩ of 2.0 mS/m or less are used, so that the phosphor particles are released from the phosphor particles in the sealing material 84 by moisture. Elution of ions can be suppressed and, further, by suppressing a decrease in the emission intensity of the light emitting device 10 , the reliability of the light emitting device 10 can be improved.

As mentioned above, although embodiment of this invention was described, these are illustrations of this invention, and various structures other than the above can also be employ|adopted.

For example, in FIG. 1 , a surface mount type LED is exemplified as the light emitting device according to the embodiment, but the light emitting device according to the embodiment may be a shell type LED.

As mentioned above, although embodiment of this invention was described, these are illustrations of this invention, and various structures other than the above can also be employ|adopted.

Example

Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to these.

(Preparation Example 1: β-sialon)

α-type silicon nitride powder (SN-E10 grade, oxygen content 1.0 mass %) manufactured by Ube Kosan Corporation 95.43 mass %, Tokuyama Corporation aluminum nitride powder (F grade, oxygen content 0.8 mass %) 3.04 mass %, Daimei Chemical Co., Ltd. aluminum oxide 0.74 mass % of powder (TM-DAR grade) and 0.79 mass % of europium oxide powder (RU grade) manufactured by Shin-Etsu Chemical Co., Ltd. were mixed using a V-type mixer (S-3 manufactured by Tsutsui Chemical Industry Co., Ltd.), In addition, the agglomeration was removed by passing through a sieve having an eye size of 250 µm to obtain a raw material mixture powder. The compounding ratio (mass%) here is _{calculated from the Si/Al ratio in the general formula of β-sialon: Si 6-z} Al _z O _z N _8-z , excluding europium oxide, so that z = 0.25 it is designed

The raw material mixed powder (200 g) having the composition of the above blending ratio was filled into a cylindrical boron nitride container (made by Denka, N-1 grade) having an inner diameter of 10 cm and a cover of 10 cm in height, and pressurized at 0.8 MPa in an electric furnace of a carbon heater. Heat treatment was performed at 2000°C for 12 hours in a nitrogen atmosphere. Since the sample after the heat treatment was in a finely agglomerated mass, this mass was coarsely pulverized with a hammer, and then pulverized with a supersonic jet pulverizer (manufactured by Nippon Pneumatic Kogyo Co., Ltd., PJM-80SP). The grinding conditions were a sample feed rate of 50 g/min and a grinding air pressure of 0.3 MPa. This pulverized powder was passed through a sieve having an eye size of 45 μm. In addition, the passage rate of the sieve was 95%.

20 g of the pulverized powder passed through the sieve was filled in a cylindrical boron nitride container with a cover having an inner diameter of 5 cm and a height of 3.5 cm, and annealed at 1500° C. for 8 hours in an electric furnace of a carbon heater in an atmospheric pressure argon atmosphere. The annealed powder was subjected to an acid treatment in which it was immersed in a 1:1 mixed acid of 50% hydrofluoric acid and 70% nitric acid at 75°C for 30 minutes. The decantation of precipitating the powder after acid treatment as it is, removing the supernatant and fine powder is repeated until the supernatant is transparent when the pH of the solution is 5 or higher, and the finally obtained precipitate is filtered and dried, and the phosphor particles of Preparation Example 1 (β-sialon phosphor powder) was obtained. As a result of powder X-ray diffraction measurement, the crystalline phase present was a β-sialon single phase. Si, Al, and Eu content measured by ICP emission spectroscopy analysis were 57.7, 2.29, and 0.62 mass %, respectively. The z value calculated from the Si and Al contents was 0.24. The compounding ratio of Production Example 1 is shown in Table 1.

(Example 1)

The phosphor particles (β-sialon phosphor powder) of Production Example 1 were subjected to surface treatment according to the following procedure.

[Surface treatment]

(1) 10 g of the phosphor particles of Production Example 1, 150 ml of ion-exchanged water, and 7.11 g of alumina sol (alumina sol 520-A, manufactured by Nissan Chemical Corporation) were mixed to prepare a slurry. The pH of the obtained slurry was 4.1. When the surface potential of the aluminum hydroxide and the surface potential of the phosphor particles at pH 4.1 were measured using a zeta potential measuring device, respectively, the surface potential of the aluminum hydroxide was 44 mV and the surface potential of the phosphor particles was 16 mV.

(2) Using a stirrer, the slurry was stirred for 15 minutes.

(3) 0.05 weight% aqueous ammonia was gradually dripped at the said slurry, and it adjusted so that pH might become 9 after 3 minutes of dripping time. When the surface potential of the aluminum hydroxide and the surface potential of the phosphor particles at pH 9 were measured using a zeta potential measuring device, respectively, the surface potential of the aluminum hydroxide was 13 mV and the surface potential of the phosphor particles was -25 mV.

(4) Using a stirrer, the slurry was stirred for 60 minutes and washed with ion-exchanged water, followed by suction filtration to obtain a phosphor powder.

(5) The obtained fluorescent substance powder was dried at 105 degreeC for 15 hours.

(6) The phosphor powder after the drying treatment was subjected to heat treatment at 600° C. for 1 hour using an electric furnace to obtain the surface-coated phosphor particles of Example 1.

The surface-coated phosphor particles of Example 1 were observed using a scanning electron microscope (SEM). Fig. 2 is an SEM image of the surface-coated phosphor particles of Example 1. As shown in Fig. 2, it was confirmed that aluminum oxide was not dotted on the surface of the phosphor particles and that the continuous coating layer was formed by continuously coating the aluminum oxide.

(Example 2)

With respect to the phosphor particles of Production Example 1, 4.74 g of AERODISP W 630 (manufactured by Evonik Resource Efficiency GmbH) was added instead of the alumina sol in (1) during the surface treatment, and the pH of the resulting slurry was 5.0, except that What was surface-treated similarly to Example 1 was made into the surface-coated fluorescent substance particle of Example 2. When the surface potential of the aluminum hydroxide and the surface potential of the phosphor particles at pH 5.0 were measured using a zeta potential measuring device, respectively, the surface potential of the aluminum hydroxide was 42 mV and the surface potential of the phosphor particles was 11 mV.

The surface-coated phosphor particles of Example 2 were observed using SEM. 3 is an SEM image of the surface-coated phosphor particles of Example 1. FIG. As shown in FIG. 3 , it was confirmed that the aluminum oxide was not dotted on the surface of the phosphor particles and that the continuous coating layer was formed by continuously coating the aluminum oxide.

(Comparative Example 1)

About the phosphor particle of manufacture example 1, the thing which did not perform the said surface treatment was set as the comparative example 1. The phosphor particles of Comparative Example 1 were observed using SEM. Fig. 4 is an SEM image of the phosphor particles of Comparative Example 1. As shown in FIG. 4 , all surfaces of the phosphor particles of Comparative Example 1 are exposed.

[Calculation method of hot water extraction electrical conductivity index]

The hot water extraction electrical conductivity index of the surface-coated phosphor particles of each Example and the phosphor particles of Comparative Example 1 was calculated in the following manner. The results obtained for the hot water extraction electrical conductivity index are shown in Table 2.

(1) was measured for electric conductivity Ω ₀ of the ion-exchanged water of 25 ℃.

(2) Dispersing 1 g of surface-coated phosphor particles (or phosphor particles) in 30 ml of the ion-exchanged water with an ultrasonic disperser, put in a pressure-resistant container and heated at 150° C. for 16 hours, then added 20 ml of ion-exchanged water and heated to 25° C. In a cooled state, electrical conductivity Ω ₁ was measured.

(3) _{The difference ΔΩ between the electrical conductivity Ω 1} and the electrical conductivity Ω ₀ (= electrical conductivity Ω ₁ -electric conductivity Ω ₀ ) was defined as the hot water extraction electrical conductivity index ΔΩ.

[Reliability Test]

The reliability test of the LED package in which the surface-coated fluorescent substance particle of each Example and the fluorescent substance particle of Comparative Example 1 were mounted was evaluated in the following way. Table 2 shows the results obtained by the reliability test.

As the LED package, one according to the structure of the light emitting device shown in FIG. 1 was used.

For mounting the phosphor into the LED package, wire bonding the lead frame and the electrode on the upper surface of the LED installed at the bottom of the case concave shape, followed by mixing phosphor particles with liquid silicone resin (OE6656, Toray Dow Corning Co., Ltd.) It was performed by injecting into the case recessed part from a micro-syringe. After mounting the phosphor particles, curing was performed at 120° C., followed by post curing at 110° C. for 10 hours, followed by sealing. As the LED, a light emission peak wavelength of 448 nm and a chip size of 1.0 mm x 0.5 mm were used.

About the LED package in which the surface-coated fluorescent substance particle of each Example and the fluorescent substance particle of the comparative example 1 obtained by the above-mentioned method were mounted, the luminous flux was measured, and it was set as the initial value L0. Moreover, after leaving it to stand at 85 degreeC and 85 %RH for 500 hours, the luminous flux L1 at the time of taking out and drying at room temperature was measured, and the reliability coefficient M (=L1/L0*100) was computed. The passing condition of the reliability test is that the reliability coefficient M is 95% or more. This is a value that cannot be achieved without highly reliable phosphor particles. In the LED package in which the surface-coated phosphor particle|grains of Example 1 and Example 2 were mounted, it was confirmed that the said pass condition was satisfied. In the surface-coated phosphor particles of Examples 1 and 2, it is estimated that this result originates in that the metal component constituting the phosphor particles is suppressed from eluting to moisture by the coating layer formed on the surface of the phosphor particles.

This application claims priority on the basis of Japanese Patent Application No. 2018-200304 for which it applied on October 24, 2018, and takes in all the indications into this specification.

Claims (6)

Phosphor particles comprising an oxynitride phosphor or a nitride phosphor;
A coating layer provided on the surface of the phosphor particles and made of a metal hydroxide or metal oxide containing at least one element selected from the group consisting of aluminum, titanium, zirconium, yttrium and hafnium
to provide
A surface-coated phosphor particle having a hot water extraction electrical conductivity index ΔΩ defined below of 2.0 mS/m or less.
(Calculation method of hot water extraction electrical conductivity index)
(1) measuring the electric conductivity Ω ₀ of the ion-exchanged water of 25 ℃.
(2) 1 g of the surface-coated phosphor particles were dispersed in 30 ml of the ion-exchanged water, put in a pressure-resistant container, and heated at 150° C. for 16 hours, after which 20 ml of ion-exchanged water was added and cooled to 25° C. Electrical conductivity Ω ₁ measure
(3) _{Let the difference ΔΩ between electrical conductivity Ω 1} and electrical conductivity Ω ₀ (= electrical conductivity Ω ₁ -electric conductivity Ω ₀ ) be the hot water extraction electrical conductivity index ΔΩ. The surface-coated phosphor particle according to claim 1, wherein the coating layer is a continuous coating layer continuously covering the surface of the phosphor particle. The surface-coated phosphor particle according to claim 1 or 2, wherein the coating layer is made of aluminum hydroxide or aluminum oxide. The phosphor particles according to any one of claims 1 to 3, wherein the phosphor particles contain Eu-containing α-sialon phosphor, Eu-containing β-sialon phosphor, Eu-containing CASN phosphor, or Eu-containing A surface-coated phosphor particle comprising a SCASN phosphor. The surface-coated fluorescent substance particle as described in any one of Claims 1-4, and the sealing material which seals the said surface-coated fluorescent substance particle.
A complex comprising a. a light emitting element that emits excitation light;
The complex according to claim 5, which converts the wavelength of the excitation light.
A light emitting device comprising a.

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