JPWO2020085049A1 - Surface-coated fluorophore particles, complexes and light-emitting devices - Google Patents

Abstract

The surface-coated phosphor particles of a certain embodiment consist of a phosphor particle composed of an oxynitride phosphor or a nitride phosphor, and a group consisting of aluminum, titanium, zirconium, yttrium and hafnium provided on the surface of the phosphor particles. It comprises a coating layer composed of a metal hydroxide or a metal oxide containing one or more selected elements. 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) Measure the electrical conductivity Ω0 of ion-exchanged water at 25 ° C. (2) 1 g of the surface-coated phosphor particles are dispersed in 30 ml of the ion-exchanged water, placed in a pressure-resistant container and heated at 150 ° C. for 16 hours, and then 20 ml of ion-exchanged water is added and cooled to 25 ° C. for electrical conduction. Measure the rate Ω1. (3) Let the difference ΔΩ (= electrical conductivity Ω1-electrical conductivity Ω0) between the electrical conductivity Ω1 and the electrical conductivity Ω0 be the hot water extraction electrical conductivity index ΔΩ.

Description

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 and converts the absorbed light into long wavelength wavelength conversion light to emit light. Is underway. As the phosphor, a nitride phosphor and an oxynitride phosphor having a relatively stable crystal structure are attracting attention.

Patent Document 1 discloses that the surface of a β-sialon phosphor is coated with a metal hydroxide in order to improve the brightness of the β-sialon phosphor.
Patent Document 2 cites, as a prior art, coating the surface of phosphor particles with a glass material for the purpose of suppressing hydrolysis of a phosphor containing sulfide by reacting with moisture in the air. Then, after pointing out the influence of the coating film on the dispersibility of the phosphor particles in the encapsulant, the surface of the phosphor particles contains a metal oxide in order to improve the dispersibility of the phosphor in the encapsulant. A method of coating with coating material particles is disclosed.
In Patent Document 3, in order to improve the gas barrier property 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 melt the surface of the phosphor particles. It is disclosed that a continuous film is formed on the surface.

Japanese Unexamined Patent Publication No. 2014-197635 Japanese Unexamined Patent Publication No. 2008-291251 Japanese Unexamined Patent Publication No. 2009-13186

The inventors investigated the characteristics of a light emitting device in which a composite in which a phosphor was sealed with a sealing material was incorporated together with an LED, and found that the light emitting intensity slightly decreased with the passage of time. As a result of investigating the cause of this phenomenon, when the moisture transferred through the encapsulant comes into contact with the phosphor, the metal component in the phosphor is ionized and eluted in the moisture, and the crystals of the phosphor gradually crystallize. It was found that the change in the structure reduces the wavelength conversion efficiency of the phosphor, which in turn leads to a decrease in the emission intensity of the light emitting device.

According to the present invention, one kind selected from the group consisting of phosphor particles composed of an oxynitride phosphor or a nitride phosphor, and aluminum, titanium, zirconium, yttrium and hafnium provided on the surface of the phosphor particles. Surface-coated phosphor particles having a coating layer composed of a metal hydroxide containing the above elements or a metal oxide, and having a hot water extraction electrical conductivity index ΔΩ defined below of 2.0 mS / m or less. Is provided.
(Calculation method of hot water extraction electrical conductivity index)
(1) Measure _{the electrical conductivity Ω 0} of the ion-exchanged water at 25 ° C.
(2) 1 g of the surface-coated phosphor particles are dispersed in 30 ml of the ion-exchanged water, placed in a pressure-resistant container and heated at 150 ° C. for 16 hours, and then 20 ml of ion-exchanged water is added and cooled to 25 ° C. for electrical conduction. the rate Ω ₁ is measured.
(3) Let the difference ΔΩ (= electrical conductivity Ω ₁ − electrical conductivity Ω _{0 ) between the electrical conductivity Ω 1} and the electrical 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-mentioned 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 including a light emitting element that emits excitation light and the above-mentioned composite that converts the wavelength of the excitation light.

According to the present invention, it is possible to suppress elution of metal components constituting phosphor particles into water.

The above-mentioned objectives and other objectives, features and advantages will be further clarified by the preferred embodiments described below and the accompanying drawings below.

It is a schematic cross-sectional view which shows the structure of the light emitting device which concerns on embodiment. It is an SEM image of the surface-coated phosphor particles of Example 1. 3 is an SEM image of the surface-coated phosphor particles of Example 2. It is an SEM image of the phosphor particles of Comparative Example 1.

As a result of diligent studies on techniques for suppressing the elution of metal components constituting the phosphor particles as ions in water, the inventors have made the morphology of the coating layer formed on the surface of the phosphor particles highly morphological. It is important to control, and in particular, it has been found that the material constituting the coating layer is selected, and the present invention has been completed. Hereinafter, embodiments of the present invention will be described in detail.

(Surface coating phosphor particles)
The surface-coated phosphor particles according to the embodiment include phosphor particles and a coating layer provided on the surface of the phosphor particles. Hereinafter, each configuration of the surface-coated phosphor particles of the present embodiment will be described.

(Fluorescent particle)

The phosphor particles consist of an oxynitride phosphor or a nitride phosphor.
Examples of the oxynitride phosphor include an α-type sialone phosphor containing Eu and a β-type sialon phosphor containing Eu.

Α-sialon phosphor containing Eu, the general _formula: represented by _{M x Eu y Si 12- (m} + n) Al (m + n) O n N 16-n. In the above general formula, M is one or more elements containing at least Ca selected from the group consisting of Li, Mg, Ca, Y and lanthanide elements (excluding La and Ce), and has a valence of M. When a is set, ax + 2y = m, x is 0 <x ≦ 1.5, 0.3 ≦ m <4.5, and 0 <n <2.25.

Β-sialon phosphor containing Eu, the general _{formula: Si 6-z Al z O} z N 8-z (z = 0.005~1) divalent europium as a luminescent center in the β-sialon represented by It is a phosphor in which (Eu ^{2+) is dissolved.}

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

The CASN phosphor containing Eu is, for example, _{a red phosphor represented by the formula CaAlSiN 3} : Eu ²⁺ , using Eu ²⁺ as an activator and having a crystal made of an alkaline earth silicate as a base. In addition, in the definition of the CASN phosphor containing Eu in this specification, the SCASN phosphor containing Eu is excluded.

The SCASN phosphor containing Eu is represented by, for example, the formula (Sr, Ca) AlSiN ₃ : Eu ^{2+ , a red phosphor having Eu 2+} as an activator and a crystal made of an alkaline earth silicate as a base. To say.

The phosphor particles of the present embodiment consist of the above-mentioned α-type sialone phosphor containing Eu, β-type sialon phosphor containing Eu, CASN phosphor containing Eu, or SCASN phosphor containing Eu. Is preferable.

The particle size of the phosphor particles is not particularly limited, and is appropriately adjusted so as to obtain dispersibility with respect to the encapsulant described later and desired wavelength conversion efficiency.

(Coating layer)
In the present embodiment, a coating layer composed of a metal hydroxide or a metal oxide containing one or more elements selected from the group consisting of aluminum, titanium, zirconium, yttrium and hafnium is formed on the surface of the phosphor particles. It is provided. The metal hydroxide or metal oxide is excellent in transparency and stability, and among them, aluminum hydroxide or aluminum oxide is preferable from the viewpoints of moisture blocking property, cost control property, coating property on phosphor particles, and the like. Used.
The coating layer may be an aggregate formed by aggregating a plurality of particles made of a metal hydroxide or a metal oxide, but is composed of a metal hydroxide or a metal oxide and forms phosphor particles. It is preferably a continuous coating layer that continuously coats. Here, the continuous coating layer has a layered structure in which a metal hydroxide or a metal oxide is formed as a continuous film, and a plurality of particles as in the invention described in Patent Document 2 are densely aggregated. It has a structure different from that of the formed aggregate. The continuous coating layer may have a concavo-convex structure in which a large number of non-penetrating recesses are formed.

The surface coverage of the phosphor particles by the coating layer is preferably 50% or more, more preferably 70% or more. By setting the surface coverage of the coating layer as described above, the amount of the metal component of the phosphor particles eluted as ions can be further suppressed. The coating layer preferably covers the entire surface of the phosphor particles.

The surface coverage by the coating layer can be evaluated by X-ray photoelectron spectroscopy (XPS) measurement. Specifically, we focus on Si, which is an element contained in the phosphor particles and not contained in the metal hydroxide or metal oxide constituting the coating layer, and by XPS measurement, on the surface of the phosphor particles of the Si. The content rate (atm%: atomic percent) is obtained. Without performing the surface treatment described later, the Si content in the phosphor particles having no metal hydroxide or coating with the metal oxide is set to A1, and the Si content in the phosphor particles for which the surface coating ratio is to be calculated is defined as A1. When A2 is used, the surface coverage of the coating layer can be calculated by the following formula.
Surface coverage (%) = (A1-A2) / A1 × 100

The lower limit of the thickness of the coating layer is preferably 0.01 μm or more, more preferably 0.1 μm or more. The upper limit of the thickness of the coating layer is preferably 10 μm or less, more preferably 5 μm or less. By setting the thickness of the coating layer to 0.01 μm or more, the amount of metal components contained in the phosphor particles eluted as ions can be further suppressed. Further, by setting the thickness of the coating layer to 10 μm or less, it is possible to suppress a decrease in the wavelength conversion efficiency of the surface-coated phosphor particles.

(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) Measure _{the electrical conductivity Ω 0} of the ion-exchanged water at 25 ° C.
(2) 1 g of surface-coated phosphor particles are dispersed in 30 ml of the above ion-exchanged water using a disperser such as an ultrasonic disperser, placed in a pressure-resistant container and heated at 150 ° C. for 16 hours, and then 20 ml of ion-exchanged water is added. _{Then, the electrical conductivity Ω 1} is measured in a state of being cooled to 25 ° C.
(3) Let the difference ΔΩ (= electrical conductivity Ω ₁ − electrical conductivity Ω _{0 ) between the electrical conductivity Ω 1} and the electrical conductivity Ω ₀ be the hot water extraction electrical conductivity index ΔΩ.
The smaller the value of the hot water extraction electrical conductivity index, the smaller the amount of metal ions eluted from the phosphor particles into water.

(Manufacturing method of surface-coated phosphor particles)
As an example of a method for producing surface-coated phosphor particles having a coating layer composed of a metal oxide, (1) a step of forming a coating layer with a substance (particles or the like) containing a metal hydroxide on the surface of the phosphor particles. , (2) By performing heat treatment, the metal hydroxide is changed to a metal oxide and the coating layer is converted into a continuous coating layer to obtain surface-coated phosphor particles having a continuous coating layer containing the metal oxide. Examples include a process and a manufacturing method including. In this production method, it is important that the coating layer made of particles containing metal hydroxide is densely coated so that it can be converted into a continuous coating layer by heat treatment.
As a method for producing such surface-coated phosphor particles, three examples of production method Examples 1 to 3 will be described below.

[Manufacturing method example 1]
Production Method Example 1 includes a slurry preparation step, a stirring step, a pH adjusting step, a stirring / washing / filtering step, a drying step, and a heating step. Details of each step will be described below.

(Slurry preparation process)
An appropriate amount of each of a substance containing phosphor powder, ion-exchanged water, and metal hydroxide is mixed to prepare a phosphor-containing slurry. The pH of the slurry obtained here is preferably in a range in which both the surface potential of the phosphor particles and the surface potential of the substance containing the metal hydroxide take positive values. Each surface potential of the substance containing the phosphor particles and the metal hydroxide can be measured by, for example, a zeta potential measuring device. When aluminum hydroxide is used as the substance containing the metal hydroxide, it can be used in the form of aluminum hydroxide in a sol state (conventionally referred to as alumina sol) or an aluminum hydroxide aqueous solution.

(Stirring process)
The slurry obtained in the slurry preparation step is stirred by 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)
In the pH adjusting step, the pH is adjusted to 9 or more by dropping an alkaline agent onto the obtained slurry at a predetermined dropping rate. Examples of the alkaline agent include alkaline _{aqueous solutions such as NH 3} aqueous solution and NaOH aqueous solution. In the process of increasing the pH value due to the addition of the alkaline agent, the surface potential of the substance containing the metal hydroxide becomes positive, and the surface potential of the phosphor particles becomes negative. As a result, the substance containing the metal hydroxide is likely to adhere to the surface of the phosphor particles in a dense manner.
Specifically, when β-type sialon phosphor particles are used as the phosphor particles and alumina sol is used as the substance containing the metal hydroxide, the surface potential of aluminum hydroxide becomes positive at a pH of 6.5 or higher. , The surface potential of β-type sialon phosphor particles becomes negative. As a result, an electrostatic attraction acts between the two, so that the substance containing aluminum hydroxide tends to adhere densely to the surface of the β-type sialon phosphor particles.

When an alkaline aqueous solution is used as the alkaline agent in the pH adjustment step, the concentration of the alkaline aqueous solution, the dropping rate and the dropping time of the substance containing the metal hydroxide adhering to the surface of the phosphor particles can be adjusted. The thickness and surface coverage can be controlled.

(Stirring / cleaning / filtration process)
The slurry obtained by the above pH adjustment step is stirred using a stirring means such as a stirrer so that the phosphor particles are sufficiently dispersed, and washed with a washing liquid such as ion-exchanged water. Then, the phosphor powder (phosphor particles coated with a substance containing a metal hydroxide) is taken out by a filtration means such as suction filtration.

(Drying process)
Heat treatment is carried out for a predetermined time so that the obtained fluorescent powder is sufficiently dried to obtain a fluorescent powder composed of a plurality of phosphor particles whose surface is densely coated with a substance containing a metal hydroxide.

(Heating process)
By heat-treating the obtained phosphor powder, a layer containing a metal hydroxide that densely coats the surface of the phosphor particles is oxidized to be converted into a metal oxide, and a continuous layer composed of the metal oxide is formed. Creates a continuous film-like morphology called a coating layer. The temperature at which the phosphor powder is heated is preferably 500 ° C. or higher and 1000 ° C. or lower, and in particular, when alumina sol is used as the substance containing the metal hydroxide, the heating temperature may be 500 ° C. or higher and 600 ° C. or lower. preferable. Through the above steps, surface-coated phosphor particles in which a continuous coating layer composed of a metal oxide is formed on the surface of the phosphor particles are produced.

[Manufacturing method example 2]
Production method example 2 has a slurry preparation step, a stirring step, a stirring / washing / filtering step, a drying step, and a heating step. In Production Method Example 1, the pH was adjusted by adding an alkaline agent after the stirring step, but in Production Method Example 2, the pH was adjusted by adding an alkaline agent in the slurry preparation step.

If the pH is adjusted by adding an alkaline agent after the stirring step as in Production Method Example 1, the coating layer made of a substance containing a metal hydroxide can be made into a more dense coating layer. The rate at which the alkaline agent is added can also be adjusted, which can further improve the denseness of the coating. By forming such a dense coating layer, a continuous coating layer can be stably obtained by the subsequent heat treatment.
On the other hand, if the pH is adjusted in the slurry preparation step as in Example 2 of the manufacturing method, the manufacturing step can be shortened.

[Manufacturing method example 3]
Production Method Example 3 has a slurry preparation step, a stirring step, a pH adjusting step, a stirring / washing / filtering step, a drying step, and a heating step. Details of each step will be described below.
In Production Method Example 1 and Production Method Example 2, a substance containing a metal hydroxide is used as a starting material for the continuous coating layer, but in Production Method Example 3, a metal hydroxide is used as a starting material for the continuous coating layer. Precursor is used.

(Slurry preparation process)
In this example, a phosphor powder, ion-exchanged water, and a precursor of a metal hydroxide are mixed in appropriate amounts to prepare a phosphor-containing slurry. When the metal hydroxide is aluminum hydroxide, sodium aluminate is used as a precursor thereof. The obtained slurry is usually strongly alkaline, specifically, pH 12 or higher is preferable, and pH 13 or higher is more preferable. A metal hydroxide is precipitated by adding an acid such as hydrochloric acid or sulfuric acid to this slurry. As a result, a phosphor-containing slurry containing a fluorescent powder, ion-exchanged 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. Specifically, pH 11 or higher is preferable, and pH 12 or higher is preferable. Is more preferable.

(Stirring process)
The slurry obtained in the slurry preparation step is stirred by using a stirring means such as a stirrer or a stirring device so that the phosphor powder and the metal hydroxide are sufficiently dispersed.

(PH adjustment process)
In the pH adjusting step, an acid such as hydrochloric acid or sulfuric acid is added dropwise to the obtained slurry at a predetermined dropping rate to adjust the pH to 9 or less. In the process of lowering the pH value due to the addition of acid, one of the surface potential of the metal hydroxide and the surface potential of the phosphor particles becomes positive, and the other surface potential becomes negative, so that the phosphor Metal hydroxides tend to adhere densely to the surface of the particles.
Specifically, when β-type sialon phosphor particles are used as the phosphor particles and aluminum hydroxide is precipitated from a slurry containing sodium aluminate, the pH is 10 or less and the surface potential of aluminum hydroxide becomes positive. , The surface potential of β-type sialon phosphor particles becomes negative. As a result, an electrostatic attraction acts between the two particles, so that aluminum hydroxide tends to adhere densely to the surface of the β-type sialon phosphor particles.
In the pH adjusting step, the thickness and surface coverage of the metal hydroxide adhering to the surface of the phosphor particles can be controlled by adjusting the concentration of the acid dropped on the slurry, the dropping rate and the dropping time. ..

After adjusting the pH, the surface of the phosphor particles is composed of a metal oxide by carrying out a stirring step, a pH adjusting step, a stirring / washing / filtering step, a drying step and a heating step in the same manner as in Production Method Example 1. Surface-coated phosphor particles on which a continuous coating layer is formed are produced.
In Production Method Example 3, after the addition of the acid in the slurry preparation step (step of precipitating the metal hydroxide from the precursor), the stirring step is carried out, and the acid is further added to adjust the pH. .. As another method, the slurry preparation step and the stirring step are performed in parallel, and the pH is adjusted by continuously adding an acid from the slurry preparation step to adjust the surface potential of the metal hydroxide and the phosphor particles. Of the surface potentials of the above, one surface potential may be positive and the other surface potential may be negative.

Here, for example, the hot water extraction electrical conductivity index can be controlled by appropriately selecting the type and amount of the metal oxide, the method of adhering the metal oxide to the surface of the phosphor particles, and the like. .. Among these, for example, pH adjustment conditions for densely adhering a substance containing a metal hydroxide to the surface of a phosphor particle, and metal oxidation of a substance containing a metal hydroxide densely adhered to the surface of a phosphor particle. The heating conditions for converting into a substance and the like can be mentioned as factors for setting the hot water extraction electrical conductivity index in a desired numerical range.

According to the surface-coated phosphor particles of the present embodiment, a coating layer composed of a metal oxide is formed on the surface of the phosphor particles so that the hot water extraction electrical conductivity index ΔΩ is 2.0 mS / m or less. As a result, when water is present around the surface-coated phosphor particles, the water is suppressed from entering the inside of the phosphor particles. As a result, the amount of ions eluted by the water is reduced, and the deterioration of the phosphor particles is suppressed.

(Light emitting device)
FIG. 1 is a schematic cross-sectional view showing the structure of the light emitting device according to the 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, a bonding wire 70, a bonding wire 72, and a composite 80.

The light emitting element 20 is mounted in a predetermined region on the upper surface of the heat sink 30. By mounting the light emitting element 20 on the heat sink 30, the heat dissipation of the light emitting element 20 can be improved. A packaging substrate may be used instead of the heat sink 30.

The light emitting element 20 is a semiconductor element that emits excitation light. As the light emitting element 20, for example, an LED chip that generates light having a wavelength of 300 nm or more and 500 nm or less, which corresponds to blue light from near-ultraviolet light, can be used. One electrode (not shown) arranged 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. Further, 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 whose hole diameter gradually increases from the bottom surface upward. The light emitting element 20 is provided on the bottom surface of the recess. The wall surface of the recess surrounding the light emitting element 20 serves as a reflector.

The complex 80 is filled in the recess where the wall surface is formed by the case 40. The complex 80 is a wavelength conversion member that lengthens the wavelength of the excitation light emitted from the light emitting element 20. As the complex 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 a resin. The light emitting device 10 emits a mixed color of the light of the light emitting element 20 and the light generated from the surface-coated phosphor particles 82 that are excited by absorbing the light of the light emitting element 20. The light emitting device 10 preferably emits white light by mixing the light of 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, by using the surface-coated phosphor particles 82 having a hot water extraction electrical conductivity index ΔΩ of 2.0 mS / m or less, fluorescence is emitted into the encapsulant 84 by moisture. By suppressing the elution of ions from the body particles and, by extension, suppressing the decrease in the emission intensity of the light emitting device 10, the reliability of the light emitting device 10 can be improved.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be 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 bullet type LED.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Production Example 1: β-type Sialon)
Ube Kosan Co., Ltd. α-type silicon nitride powder (SN-E10 grade, oxygen content 1.0% by mass) 95.43% by mass, Tokuyama Co., Ltd. aluminum nitride powder (F grade, oxygen content 0.8% by mass) 3 .04% by mass, aluminum oxide powder (TM-DAR grade) manufactured by Daimei Chemical Co., Ltd. 0.74% by mass, Europium oxide powder (RU grade) manufactured by Shinetsu Chemical Industry Co., Ltd. 0.79% by mass, V-type mixer (Tsutsui Rikagaku Kikai) The mixture was mixed using S-3) manufactured by the same company, and further passed through a sieve having a mesh size of 250 μm to remove agglomerates to obtain a raw material mixed powder. The compounding ratio (mass%) here is calculated from the Si / Al ratio in the general formula of β-type sialon: Si _6-z Al _{z Oz} N _8-z , excluding europium oxide, and z = 0. It was designed to be 25.

200 g of a raw material mixed powder having the composition of the above compounding ratio is filled in a cylindrical boron nitride container (manufactured by Denka, N-1 grade) with a lid having an inner diameter of 10 cm and a height of 10 cm, and is used in an electric furnace of a carbon heater. Heat treatment was performed at 2000 ° C. for 12 hours in a pressurized nitrogen atmosphere of 8 MPa. Since the sample after the heat treatment was in the form of loosely agglomerated lumps, the lumps were roughly crushed with a hammer and then crushed with a supersonic jet crusher (PJM-80SP, manufactured by Nippon Pneumatic Industries Co., Ltd.). The crushing conditions were a sample supply rate of 50 g / min and a crushing air pressure of 0.3 MPa. The pulverized powder was passed through a sieve having an opening of 45 μm. The passing rate of the sieve was 95%.

20 g of the crushed powder passed through the above sieve is filled in a cylindrical boron nitride container with a lid 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. Processing was performed. The annealed powder was subjected to acid treatment by immersing it in a 1: 1 mixed acid of 50% hydrofluoric acid and 70% nitric acid at 75 ° C. for 30 minutes. The powder after acid treatment is precipitated as it is, and decantation for removing the supernatant and fine particles is repeated until the pH of the solution is 5 or more and the supernatant becomes transparent, and the finally obtained precipitate is filtered and dried. The phosphor particles of Production Example 1 (β-type sialon phosphor powder) were obtained. As a result of powder X-ray diffraction measurement, the existing crystal phase was β-type sialon single phase. The Si, Al and Eu contents measured by ICP emission spectroscopic analysis were 57.7, 2.29 and 0.62% by 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-type sialon phosphor powder) of Production Example 1 were surface-treated by the following procedure.

[surface treatment]
(1) A slurry was prepared by mixing 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 Industries, Ltd.). The pH of the obtained slurry was 4.1. When the surface potential of aluminum hydroxide and the surface potential of the phosphor particles at pH 4.1 were measured using a zeta potential measuring device, the surface potential of aluminum hydroxide was 44 mV and the surface potential of the phosphor particles was 16 mV. rice field.
(2) The slurry was stirred for 15 minutes using a stirrer.
(3) 0.05 wt% aqueous ammonia was gradually added dropwise to the slurry, and the pH was adjusted to 9 after 3 minutes of the addition time. When the surface potential of aluminum hydroxide and the surface potential of the phosphor particles at pH 9 were measured using a zeta potential measuring device, the surface potential of aluminum hydroxide was 13 mV and the surface potential of the phosphor particles was -25 mV. there were.
(4) The slurry was stirred for 60 minutes using a stirrer, washed with ion-exchanged water, and then suction-filtered to obtain a phosphor powder.
(5) The obtained fluorescent powder was dried at 105 ° C. for 15 hours.
(6) The fluorescent powder after the drying treatment was heat-treated at 600 ° C. for 1 hour using an electric furnace to obtain surface-coated fluorescent 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 the continuous coating layer was formed by continuously coating the aluminum oxide without interspersing the surface of the phosphor particles.

(Example 2)
To the phosphor particles of Production Example 1, 4.74 g of AERODISP W 630 (manufactured by Evonik Resources Efficiency GmbH) was added instead of the alumina sol of (1) in the above surface treatment, and the pH of the obtained slurry was 5.0. The surface-coated phosphor particles of Example 2 were those subjected to the same surface treatment as in Example 1 except that the particles were the same as in Example 1. When the surface potential of aluminum hydroxide and the surface potential of the phosphor particles at pH 5.0 were measured using a zeta potential measuring device, the surface potential of aluminum hydroxide was 42 mV and the surface potential of the phosphor particles was 11 mV. rice field.
The surface-coated phosphor particles of Example 2 were observed using SEM. FIG. 3 is an SEM image of the surface-coated phosphor particles of Example 1. As shown in FIG. 3, it was confirmed that the continuous coating layer was formed by continuously coating the aluminum oxide without interspersing the surface of the phosphor particles.

(Comparative Example 1)
The phosphor particles of Production Example 1 that were not subjected to the above surface treatment were designated as 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, the surface of the phosphor particles of Comparative Example 1 is completely 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 as follows. Table 2 shows the results obtained for the hot water extraction electrical conductivity index.
_{(1) The electric conductivity Ω 0} of the ion-exchanged water at 25 ° C. was measured.
(2) 1 g of surface-coated phosphor particles (or phosphor particles) are dispersed in 30 ml of the above ion-exchanged water by an ultrasonic disperser, placed in a pressure-resistant container and heated at 150 ° C. for 16 hours, and then 20 ml of ion-exchanged water is added. _{The electrical conductivity Ω 1} was measured while cooled to 25 ° C.
(3) The difference ΔΩ (= electrical conductivity Ω ₁ − electrical conductivity Ω _{0 ) between the electrical conductivity Ω 1} and the electrical conductivity Ω ₀ was defined as the hot water extraction electrical conductivity index ΔΩ.

[Reliability test]
The reliability test of the surface-coated phosphor particles of each example and the LED package equipped with the phosphor particles of Comparative Example 1 was evaluated as follows. The results obtained by the reliability test are shown in Table 2.
The LED package used was one that conformed to the structure of the light emitting device shown in FIG.
To mount the phosphor on the LED package, the electrode on the upper surface of the LED installed on the bottom of the concave case and the lead frame were wire-bonded and then mixed with a liquid silicone resin (OE6656, manufactured by Toray Dow Corning Co., Ltd.). The phosphor particles were injected into the recesses of the case from a microsyringe. After mounting the fluorescent particles, the particles were cured at 120 ° C., and then post-cured at 110 ° C. for 10 hours for sealing. As the LED, an LED having an emission peak wavelength of 448 nm and a chip size of 1.0 mm × 0.5 mm was used.

The luminous flux of the LED package equipped with the surface-coated phosphor particles of each example and the phosphor particles of Comparative Example 1 obtained in the above-mentioned procedure was measured and set to an initial value of L0. Further, the luminous flux L1 when taken out and dried at room temperature after being left at 85 ° C. and 85% RH for 500 hours was measured, and the reliability coefficient M (= L1 / L0 × 100) was calculated. 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. It was confirmed that the LED packages equipped with the surface-coated phosphor particles of Examples 1 and 2 satisfy the above-mentioned acceptance conditions. As a result, in the surface-coated phosphor particles of Examples 1 and 2, the coating layer formed on the surface of the phosphor particles suppressed the metal components constituting the phosphor particles from being eluted into water. It is presumed that this is the cause.

This application claims priority on the basis of Japanese application Japanese Patent Application No. 2018-200304 filed on October 24, 2018, the entire disclosure of which is incorporated herein by reference.

Claims (6)

With phosphor particles composed of an oxynitride phosphor or a nitride phosphor,
A coating layer provided on the surface of the phosphor particles and composed of a metal hydroxide or a metal oxide containing one or more elements selected from the group consisting of aluminum, titanium, zirconium, yttrium and hafnium.
With
Surface-coated phosphor particles 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) Measure _{the electrical conductivity Ω 0} of the ion-exchanged water at 25 ° C.
(2) 1 g of the surface-coated phosphor particles are dispersed in 30 ml of the ion-exchanged water, placed in a pressure-resistant container and heated at 150 ° C. for 16 hours, and then 20 ml of ion-exchanged water is added and cooled to 25 ° C. for electrical conduction. the rate Ω ₁ is measured.
(3) Let the difference ΔΩ (= electrical conductivity Ω ₁ − electrical conductivity Ω _{0 ) between the electrical conductivity Ω 1} and the electrical conductivity Ω ₀ be the hot water extraction electrical conductivity index ΔΩ. The surface-coated phosphor particles according to claim 1, wherein the coating layer is a continuous coating layer that continuously covers the surface of the phosphor particles. The surface-coated phosphor particles according to claim 1 or 2, wherein the coating layer is made of aluminum hydroxide or aluminum oxide. Any of claims 1 to 3, wherein the phosphor particles consist of an α-type sialone phosphor containing Eu, a β-type sialon phosphor containing Eu, a CASN phosphor containing Eu, or a SCASN phosphor containing Eu. The surface-coated phosphor particles according to item 1. The surface-coated fluorescent particle according to any one of claims 1 to 4, and a sealing material for sealing the surface-coated fluorescent particle.
Complex with. A light emitting element that emits excitation light and
The complex according to claim 5, which converts the wavelength of the excitation light, and
A light emitting device equipped with.

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