JP7208056B2 - Method for producing β-sialon phosphor - Google Patents

Description

The present invention relates to a method for producing a β-sialon phosphor.

Various developments have been made on β-SiAlON phosphors. As this type of technology, for example, the technology described in Patent Document 1 is known. In Patent Document 1, a metal element M (where M is one or more selected from Mn, Ce, and Eu) is added in a nitride or oxynitride crystal having a β-type Si ₃ N ₄ crystal structure. element) in solid solution, and emits fluorescence having a peak in the wavelength range of 500 nm to 600 nm by irradiation with an excitation source (claim of Patent Document 1). Item 1).

JP 2005-255895 A

However, as a result of investigation by the present inventors, it was found that the β-sialon phosphor described in Patent Document 1 has room for improvement in terms of luminance maintenance factor when applied to a light-emitting device.

β-SiAlON is easily hydrolyzed, which may cause a change in brightness over time when applied to a light-emitting device. As a result of further studies by the present inventors, a β-sialon phosphor capable of improving the reliability of a light-emitting device by coating (covering) the surface of β-sialon particles with silicone oil and heat-treating the particles was found. We found that it can be realized, and came to complete the present invention.

According to the invention,
a preparation step of preparing β-sialon particles;
a surface treatment step of performing a heat treatment in a state where the β-type sialon particles and silicone oil coexist;
A method for producing a β-sialon phosphor is provided, comprising:

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of (beta)-sialon fluorescent substance excellent in the luminance maintenance factor of a light-emitting device is provided.

2 is a diagram showing infrared absorption spectra obtained by FT-IR measurement of the β-sialon phosphors of Example 2 and Comparative Example 1. FIG.

An outline of the method for producing the β-sialon phosphor of the present embodiment will be described.

The method for producing the β-sialon phosphor includes a preparation step of preparing β-sialon particles, and a surface treatment step of performing heat treatment while the β-sialon particles and silicone oil are coexistent.

The inventor has found the following.
Hydrolysis of the β-sialon causes deterioration, ion elution, and the like, which may reduce the reliability of the light-emitting device. Therefore, in order to suppress hydrolysis, we thought that it would be effective if we could prevent contact with water by coating the surface of β-SiAlON.

From the viewpoint of imparting water repellency, organic matter was examined from among various materials. However, oleic acid turns black when heated during the manufacturing process of the light-emitting device, which may reduce the brightness of the light-emitting device. As a result of further studies, the inventors have focused on silicone oil (organopolysiloxane), which has excellent heat resistance. However, it has been found that sufficient reliability of the light-emitting device cannot be obtained only by mixing the β-SiAlON particles and the silicone oil and coating the surface.

As a result of intensive studies based on such development circumstances, it was found that a β-SiAlON phosphor capable of improving the reliability of a light-emitting device can be realized by appropriately heat-treating a mixture of β-SiAlON particles and silicone oil. found. Although the detailed mechanism is not clear, it is believed that the heat treatment volatilizes the low-molecular-weight components in the silicone oil, making the coating state of the silicone oil appropriate.

According to this embodiment, by using the β-SiAlON phosphor in the light emitting device, it is possible to improve the high temperature and high humidity reliability and increase the luminance retention rate.

The β-sialon phosphor of this embodiment will be described in detail below.

The β-sialon phosphor is extremely useful as a light source phosphor for light emitting diodes (hereinafter referred to as LEDs). It can be used for LEDs that emit light.

The β-sialon phosphor contains β-sialon particles and silicone oil adhering to the surfaces of the β-sialon particles. That is, the β-sialon phosphor may be composed of one or more β-sialon particles whose surfaces are coated with silicone oil. The silicone oil may constitute a silicone coating layer formed on the surface of the β-sialon particles.

As used herein, attachment may be in a state of being bound by either chemical bonding, physical bonding, or both. Covering may be either a state of partially covering the surface or a state of covering the entire surface.

An infrared absorption spectrum is obtained by FT-IR measurement of the β-SiAlON phosphor. The β-sialon phosphor may be configured such that the infrared absorption spectrum has a peak derived from Si—CH ₃ . This indicates that the silicone oil adheres to the surface of the β-sialon particles.

As the above silicone oil, a known one can be used, but one selected from the viewpoint of heat resistance, transparency and the like may be used. Among them, a colorless and transparent silicone oil is preferable.

As the silicone oil, for example, dimethylpolysiloxane, methylphenylsiloxane, methylhydrogenpolysiloxane, and modified products thereof may be used. These may be used alone or in combination of two or more. From the viewpoint of heat resistance, a polysiloxane having a phenyl group in the molecule such as methylhydrogenpolysiloxane may be used.

The β-sialon particles are not particularly limited as long as they can be used as a phosphor, and may be composed of β-sialon in which europium is solid-dissolved. Specifically, the β-sialon particles are represented by the general formula Si _6-z Al _z O _z N _8-z :Eu ²⁺ (0<z≦4.2 ⁾ , and are β It may consist of a mold sialon.

In the general formula Si _6-z Al _z O _z N _8-z :Eu ²⁺ , the z value and the europium content are not particularly limited, but the z value is, for example, more than 0 and 4.2 or less, and β-type From the viewpoint of further improving the emission intensity of the sialon phosphor, it is preferably 0.005 or more and 1.0 or less. Moreover, the content of europium is preferably 0.1% by mass or more and 2.0% by mass or less.

The average particle size d50 of the β-sialon particles is, for example, 0.1 μm to 50 μm, preferably 0.2 μm to 40 μm, more preferably 0.5 μm to 30 μm. By making it equal to or less than the upper limit, variations in the chromaticity of the emitted light can be suppressed. Brightness can be improved by making it more than a lower limit.
The average particle diameter d50 is a value calculated from the volume average diameter measured by the laser diffraction scattering method.

The β-SiAlON phosphor may be one in which a plurality of particles are firmly integrated during heat treatment in the firing step.

Next, a method for producing the β-sialon phosphor of this embodiment will be described.

The method for producing the β-sialon phosphor includes a preparation step of preparing β-sialon particles, and a surface treatment step of performing heat treatment while the β-sialon particles and silicone oil are coexistent.

For the preparation step of preparing the β-sialon particles, a known method may be used. It may also include post-treatment steps such as pulverization treatment, classification treatment, annealing treatment and acid treatment.

In the surface treatment step, the surface of the β-sialon particles can be heat-treated while the silicone oil is in contact with the surface. Specifically, a mixture of β-sialon particles and silicone oil may be heat-treated.

In the surface treatment step, the lower limit of the heat treatment temperature is, for example, 180° C. or higher, preferably 190° C. or higher, and more preferably 200° C. or higher. This makes it possible to modify the state of coating with the silicone oil and improve the luminance maintenance factor of the light emitting device. On the other hand, the upper limit of the heat treatment temperature is, for example, 400° C. or lower, preferably 380° C. or lower, and more preferably 350° C. or lower. Thereby, decomposition of the silicone oil can be suppressed, and a decrease in brightness of the light emitting device can be suppressed.

In the surface treatment step, the heating time of the heat treatment can be appropriately set, and may be, for example, 30 minutes to 10 hours. Moreover, the surface treatment process may be performed in an air atmosphere, for example, under conditions of humidity of 80% or less. It is preferable that there is relatively little moisture in the environment of the heat treatment.

In the surface treatment step, the upper limit of the amount of silicone oil added is, for example, 10% by weight or less, preferably 8% by weight or less, and more preferably 5% by weight or less with respect to 100% by weight of the β-sialon phosphor. be. As a result, it is possible to suppress a decrease in the absorbance of the β-sialon phosphor for blue light. On the other hand, the lower limit of the amount of silicone oil to be added is, for example, 0.01% by weight or more, preferably 0.05% by weight or more, and more preferably 0.10% by weight with respect to 100% by weight of the β-sialon phosphor. % or more. Thereby, the luminance maintenance factor of the light-emitting device can be improved.

As described above, a β-sialon phosphor can be obtained.
In addition, after the surface treatment step, a known step may be added as necessary. For example, post-treatments such as crushing/classification treatment, purification treatment, and drying treatment may be performed.

(Wavelength converter)
The wavelength converter of the present embodiment converts light emitted from a light emitting element to emit light, and includes the β-sialon phosphor. The wavelength converter may be composed only of the β-SiAlON phosphor, or may include a base material in which the β-SiAlON phosphor is dispersed. As the base material, known materials can be used, and examples thereof include glass, resins, inorganic materials, and the like.

The shape of the wavelength conversion body is not particularly limited, and it may be configured in a plate shape, or may be configured to seal a part of the light emitting element or the entire light emitting surface.

(light emitting device)
A light-emitting device according to this embodiment includes a light-emitting member including a light-emitting source (light-emitting element) and the wavelength converter.
Light having a high emission intensity can be emitted by combining the light emission source and the wavelength converter.

An example of a light emitting device is an LED package. The LED package may include a light emitting source (LED chip), a substrate (lead frame) on which the light emitting source is mounted, and a wavelength converter covering the light emitting source. The LED chip may generate light with a wavelength of 300 nm to 500 nm from near-ultraviolet to blue light. The LED chip and lead frame may be electrically connected by bonding wires. The wavelength converter may be covered with a synthetic resin cap.

The wavelength converter may contain the β-SiAlON phosphor, but may also contain other phosphors. Other phosphors may further include phosphors such as α-SiAlON phosphors, KSF phosphors, CASN phosphors, and YAG phosphors alone or in mixtures. Elements solid-dissolved in these phosphors include, for example, europium (Eu), cerium (Ce), strontium (Sr), calcium (Ca), and manganese (Mn). These phosphors may be used singly or in combination of two or more.

In the case of the light-emitting device using the β-sialon phosphor, by irradiating near-ultraviolet light or visible light containing a wavelength of 300 nm or more and 500 nm or less as an excitation source as a light emission source, the range of 520 nm or more and 550 nm or less It has a green emission characteristic with a peak at the wavelength of . For this reason, a near-ultraviolet LED chip or a blue LED chip and a β-sialon phosphor are used as a light source, and a red-emitting phosphor, a blue-emitting phosphor, a yellow-emitting phosphor, or an orange-emitting phosphor having a wavelength of 600 nm or more and 700 nm or less is used. White light can be obtained by combining phosphors alone or in mixtures.

For example, a combination of a β-SiAlON phosphor exhibiting green and a KSF-based phosphor exhibiting red can be suitably used for backlight LEDs suitable for high-color-rendering TVs and the like.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can be adopted. Moreover, the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the description of these Examples.

<Preparation of β-SiAlON Phosphor>
(Comparative example 1)
For the β-sialon phosphor of Comparative Example 1, as described below, a firing step was performed to obtain a fired product by firing the raw material mixed powder, and the fired product after the firing step was further subjected to crushing, pulverization, and classification. Treated, annealed and acid treated.

(Baking process, raw material mixed powder and baking)
α-type silicon nitride (SN-E10 grade, oxygen content 1.0% by mass, manufactured by Ube Industries) 95.58% by mass, aluminum nitride (E grade, oxygen content 0.8% by mass, manufactured by Tokuyama) 2 89% by mass, 0.93% by mass of aluminum oxide (TM-DAR grade, manufactured by Taimei Chemical Co., Ltd.), and 0.60% by mass of europium oxide (RU grade, manufactured by Shin-Etsu Chemical Co., Ltd.). The compounding ratio of the raw materials was designed so that, in the general formula of the β-sialon: Si _6-z Al _z O _z N _8-z , z=0.25 excluding europium oxide. This raw material mixed powder was dry-mixed for 10 minutes with a V-type mixer (S-3, manufactured by Tsutsui Rikagaku Kikai Co., Ltd.). Of the raw materials after mixing, those that passed through a nylon sieve with an opening of 250 μm were used in the following steps. The mixture is filled in a cylindrical boron nitride container with a lid (N-1 grade, manufactured by Denka), and left at 2000 ° C. for 15 hours in a pressurized nitrogen atmosphere of 0.8 MPa in an electric furnace with a carbon heater. Firing was performed. After the baking was completed, it was taken out from the container and allowed to stand until it reached room temperature.

(Crushing, pulverizing, and classifying the fired product)
The obtained lumpy baked product was pulverized with a roll crusher, passed through a sieve with an opening of 150 μm, and the powder was used for the following treatment.

(annealing treatment)
The powder after the firing step was held at 1450° C. for 8 hours under an argon gas atmosphere at an atmospheric pressure of 0.15 MPa.

(acid treatment)
The annealed powder was acid-treated by immersing it in a mixed acid of hydrofluoric acid and nitric acid for 30 minutes. In order to separate the acid from the acid-treated powder, the mixed acid was passed through a synthetic resin filter, and the powder remaining on the filter was washed with water to obtain β-sialon phosphor A of Comparative Example 1.

(Comparative example 2)
To 100% by weight of the β-SiAlON phosphor A of Comparative Example 1, 1.0% by weight of silicone oil (TSF-4300 manufactured by Momentive) was added and mixed to obtain a mixture. The resulting mixture was used as β-sialon phosphor B.

(Comparative Example 3)
A mixture obtained in the same manner as in Comparative Example 2 was used as β-sialon phosphor C, except that the amount of silicone oil added was changed to 0.5% by weight.

(Comparative Example 4)
A mixture obtained in the same manner as in Comparative Example 2 was used as β-sialon phosphor D, except that the amount of silicone oil added was changed to 3.0% by weight.

(Example 1)
30 g of the β-sialon phosphor B obtained in Comparative Example 2 was placed in an evaporating dish, and heat treatment was performed at 200° C. for 2 hours on a hot plate in a draft with a humidity of 59% to obtain a β-sialon phosphor. got E.

(Example 2)
30 g of the β-SiAlON phosphor B obtained in Comparative Example 2 was placed in an evaporating dish, and heat-treated at 300° C. for 2 hours on a hot plate in a draft with a humidity of 52% to obtain a β-SiAlON phosphor. got F.

(Example 3)
30 g of the β-sialon phosphor B obtained in Comparative Example 2 was placed in an evaporating dish, and heat-treated at 350° C. for 2 hours on a hot plate in a draft with a humidity of 67% to obtain a β-sialon phosphor. got a G.

(Example 4)
30 g of the β-sialon phosphor C obtained in Comparative Example 3 was placed in an evaporating dish, and heat-treated at 300° C. for 2 hours on a hot plate in a draft with a humidity of 80% to obtain a β-sialon phosphor. obtained H.

(Example 5)
30 g of the β-SiAlON phosphor D obtained in Comparative Example 4 was placed in an evaporating dish, and heat-treated at 300° C. for 2 hours on a hot plate in a draft with a humidity of 34% to obtain a β-SiAlON phosphor. obtained I.

The amount of silicone oil in Table 1 means the amount adhered to the surface of the β-sialon particles. X weight % represents the adhesion amount (weight %) of silicone oil with respect to 100 weight % of the β-SiAlON phosphor.
In Comparative Examples 2 to 4, it was confirmed that all of the added silicone oil adhered to the β-sialon particles, so the added amount of silicone oil was taken as the adhered amount.
On the other hand, in Examples 1 to 5, from the amount of silicone oil added, the volatile content of silicone oil when heat treated at the heating temperature (200 ° C., 300 ° C., 350 ° C.) and heating time (2 hours) of each example was taken as the amount of adhesion.

The following characteristics and evaluation items were evaluated for the β-sialon phosphors of each example and each comparative example.
Table 1 shows the evaluation results.

(IR spectrum)
The β-sialon phosphors of Example 2 and Comparative Example 1 were subjected to FT-IR measurement to obtain infrared absorption spectra. The obtained infrared absorption spectrum is shown in FIG.
As a result of FIG. 1, in Example 2, a peak derived from Si—CH ₃ symmetric bending vibration was observed at 1260 cm ⁻¹ , but in Comparative Example 1, the peak was not observed.

(luminous flux maintenance factor)
The reliability test of the LED packages equipped with the β-SiAlON phosphors of each example and each comparative example was evaluated in the following manner. Table 1 shows the results obtained by the reliability test.
The β-SiAlON phosphor is mounted on the LED package by wire-bonding the electrode on the upper surface of the LED installed at the bottom of the recessed case and the lead frame, followed by applying liquid silicone resin (OE6656, manufactured by Dow Corning Toray Co., Ltd.). The mixed β-SiAlON phosphor was injected into the concave portion of the case from a microsyringe. After the β-SiAlON phosphor was mounted, it was cured at 120° C., and then post-cured at 110° C. for 10 hours, followed by sealing. The LED used had an emission peak wavelength of 448 nm and a chip size of 1.0 mm×0.5 mm.

The luminous flux was measured for the LED packages mounting the β-sialon phosphors of each example and each comparative example obtained in the manner described above, and the initial value was L0. Also, after standing at 85° C. and 85% RH for 500 hours, the luminous flux L1 was measured when it was taken out and dried at room temperature, and the luminous flux maintenance factor (=L1/L0×100) was calculated.
A passing condition of the reliability test is a luminous flux maintenance factor of 95% or more. It was shown that highly reliable surface-coated phosphor particles can be realized with the β-sialon phosphors E to I of each example.

(Comparative Example 5)
A β-sialon phosphor J was obtained in the same manner as in Example 1, except that oleic acid was used instead of the silicone oil. When the β-SiAlON phosphor J was used, oleic acid turned black due to heating in the process of manufacturing the package, resulting in a 15% decrease in package brightness.

It was shown that the use of the β-sialon phosphors of Examples 1-5 improved the luminous flux maintenance factor compared to Comparative Examples 1-4. By using the β-SiAlON phosphors of Examples 1 to 5 in a light-emitting device, it is possible to improve the high-temperature and high-humidity reliability and increase the luminance retention rate.

Claims (7)

a preparation step of preparing β-sialon particles;
a surface treatment step of performing a heat treatment in a state where the β-type sialon particles and silicone oil coexist;
A method for producing a β-sialon phosphor, comprising: A method for producing the β-sialon phosphor according to claim 1,
In the surface treatment step, the temperature of the heat treatment is set to 180 ° C. or higher and 400 ° C. or lower,
A method for producing a β-sialon phosphor. A method for producing the β-sialon phosphor according to claim 1 or 2,
In the surface treatment step, performed in an air atmosphere at a humidity of 80% or less,
A method for producing a β-sialon phosphor. A method for producing a β-sialon phosphor according to any one of claims 1 to 3,
The silicone oil contains one or more selected from the group consisting of dimethylpolysiloxane, methylphenylsiloxane, methylhydrogenpolysiloxane, and modified products thereof,
A method for producing a β-sialon phosphor. A method for producing a β-sialon phosphor according to any one of claims 1 to 4,
In the surface treatment step, the amount of the silicone oil added is 0.01% by weight or more and 10% by weight or less with respect to 100% by weight of the β-sialon phosphor.
A method for producing a β-sialon phosphor. A method for producing a β-sialon phosphor according to any one of claims 1 to 5,
The average particle diameter d50 of the β-sialon particles is 0.1 μm or more and 50 μm or less,
A method for producing a β-sialon phosphor. A method for producing a β-sialon phosphor according to any one of claims 1 to 6,
The β-sialon particles are represented by the general formula Si _6-z Al _z O _z N _8-z :Eu ²⁺ (0<z≦4.2) and are composed of β-sialon in which Eu ²⁺ is dissolved. Ru
A method for producing a β-sialon phosphor.

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