Method for manufacturing β-type sialon phosphor, method for manufacturing wavelength conversion member, and method for manufacturing light-emitting device

Abstract

To provide a method for producing a β sialon phosphor having excellent thermal deterioration resistance.SOLUTION: A method for producing a β sialon phosphor includes a preparation step for mixing raw material powder containing silicon, aluminum and europium and firing the mixture, to prepare a β sialon phosphor with europium dissolved therein, and an alkali treatment step for heating the β sialon phosphor with a solid basic substance attached to its surface.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a β-sialon phosphor, a method for manufacturing a wavelength conversion member, and a method for manufacturing a light emitting device. [Background technology]

[0002] Various developments have been made in the field of β-sialon phosphors. Patent Document 1, for example, describes a method for producing a β-sialon phosphor, which comprises heat-treating a composition containing silicon nitride containing aluminum, oxygen atoms, and europium, mixing the resulting mixture with a sodium hydroxide solution, and subjecting the resulting mixture to a first thermal base treatment at 70°C for 3 hours in the atmosphere, followed by a second thermal base treatment at 200°C for 2 hours in a nitrogen atmosphere (see, for example, Claims 1 and 3, paragraph 0009, Example 6, etc., of Patent Document 1). Furthermore, Patent Document 1 also discloses that the first temperature, which is the heating temperature for the first thermal base treatment, is between 50°C and 150°C (paragraph 0051). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-110206 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of investigations by the present inventors, it has been found that the β-sialon phosphor obtained by the manufacturing method described in Patent Document 1 has room for improvement in terms of resistance to thermal degradation. [Means for solving the problem]

[0005] Further investigation by the inventors revealed that when a fired product of a raw material powder mixture containing Si, Al, and Eu is heated in a basic aqueous solution, the diffuse reflectance of the β-sialon phosphor decreases after a heat degradation test. Although the detailed mechanism is unclear, it is thought that during the heating process, the surface of the fired material becomes rich in OH groups due to the water present in the basic aqueous solution, which reduces the optical properties of the β-sialon phosphor.

[0006] As a result of intensive research based on this knowledge, the present inventors discovered that by heating the above-mentioned fired product with a solid basic substance attached to the surface, the decrease in diffuse reflectance of the β-sialon phosphor after a heat degradation test can be suppressed, and thus the present invention was completed.

[0007] According to the present invention, a preparation step of mixing raw material powders containing silicon, aluminum, and europium, and firing the mixture to prepare a β-sialon phosphor containing europium as a solid solution; an alkali treatment step of heating the β-sialon phosphor with a solid basic substance attached to its surface; The present invention provides a method for producing a β-sialon phosphor, comprising:

[0008] Further, according to the present invention, There is provided a method for producing a wavelength conversion member, which includes a step of producing a wavelength conversion member using a β-sialon phosphor obtained by the above-mentioned method for producing a β-sialon phosphor.

[0009] Further, according to the present invention, There is provided a method for manufacturing a light emitting device, which includes a step of mounting a wavelength conversion member obtained by the above-described method for manufacturing a wavelength conversion member on a light emitting surface of a light emitting source. [Effects of the Invention]

[0010] According to the present invention, there are provided a method for producing a β-sialon phosphor having excellent resistance to thermal degradation, a wavelength conversion member using the same, and a light emitting device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view schematically showing the structure of an LED package used in a reliability test. [Figure 2] The results of the reliability test of the LED package are shown. DETAILED DESCRIPTION OF THE INVENTION

[0012] An outline of the method for producing the β-sialon phosphor of this embodiment will be described.

[0013] The method for producing a β-sialon phosphor includes a preparation step of mixing raw material powders containing silicon, aluminum, and europium and firing the mixture to prepare a β-sialon phosphor in which europium is dissolved, and an alkali treatment step of heating the β-sialon phosphor with a solid basic substance attached to its surface.

[0014] According to the findings of the present inventors, it has been found that an alkali treatment in which a solid basic substance is attached to the surface of a β-sialon phosphor and the phosphor is heated suppresses the decrease in diffuse reflectance of the β-sialon phosphor after a heat degradation test.

[0015] Although the detailed mechanism is unclear, it can be speculated as follows. An unstable oxide layer containing a large amount of Si-OH is formed on the surface of the β-SiAlON phosphor, and after thermal degradation testing, excess light absorption due to defects originating from Si-OH increases. In contrast, by subjecting the surface of a β-SiAlON phosphor to an alkali treatment in which the phosphor is heated in the substantial absence of water, the Si—OH groups on the surface are reduced, which makes it possible to suppress the increase in excess light absorption after the thermal degradation test. This is thought to prevent the deterioration of the optical properties of the β-SiAlON phosphor.

[0016] According to this embodiment, reduction of the diffuse reflectance after the heat deterioration test is suppressed, and a β-type sialon phosphor excellent in heat deterioration resistance can be realized. By using such a β-type sialon phosphor for a wavelength conversion member or a light-emitting device, the thermal reliability can be improved.

[0017] Hereinafter, the β-type sialon phosphor of this embodiment will be described in detail.

[0018] The β-type sialon phosphor of this embodiment is extremely useful as a phosphor for a light source such as a Light Emitting Diode (hereinafter referred to as LED).

[0019] The β-type sialon phosphor can absorb blue light in the wavelength range of, for example, 420 nm to 480 nm and emit light having a peak wavelength in the range exceeding 480 nm and not exceeding 800 nm.

[0020] [[ID=I6]]The β-type sialon phosphor is not particularly limited as long as it can be used as a phosphor, but is composed of europium-activated β-type sialon in which europium is dissolved.

[0021] The β-type sialon phosphor has the general formula Si 6-z Al z O z N 8-z :Eu 2+ (0 < z ≦ 4.2). In the general formula Si 6-z Al z O z N 8-z :Eu 2+ although the z value and the europium content are not particularly limited, the z value is, for example, more than 0 and 4.2 or less, and from the viewpoint of further improving the emission intensity of the β-type sialon phosphor, it is preferably 0.005 or more and 1.0 or less. Further, the content of europium in the β-type sialon phosphor is preferably, for example, 0.1 mass% or more and 2.0 mass% or less.

[0022] The β-sialon phosphor may be in powder form and configured to have an average particle diameter d50 of, for example, 0.1 μm to 50 μm, preferably 0.25 μm to 40 μm, and more preferably 0.5 μm to 30 μm. By setting it to the upper limit or less, variations in the chromaticity of the emitted color can be suppressed. By setting it to the lower limit or more, brightness can be improved.

[0023] The average particle diameter d50 is a value calculated from the volume average diameter measured by a laser diffraction scattering method. The particle size distribution was measured according to the laser diffraction / scattering method described in JIS R 1629:1997, "Method for measuring particle size distribution of fine ceramic raw materials by laser diffraction / scattering." A particle size distribution analyzer (Microtrac-Bell Corporation, product name: "Microtrac MT3300EX II") was used for the measurement. Specifically, 0.1 g of the target phosphor was first added to 100 mL of ion-exchanged water and dispersed for 3 minutes using an ultrasonic homogenizer (Nihon Seiki Seisakusho Co., Ltd., product name: "Ultrasonic Homogenizer US-150E," tip size: φ20, amplitude: 100%, oscillation frequency: 19.5 kHz, amplitude: approximately 31 μm) to prepare the measurement sample. The particle size was then measured using the particle size distribution analyzer.

[0024] Next, a method for producing the β-sialon phosphor of this embodiment will be described.

[0025] An example of a method for producing a β-sialon phosphor of this embodiment includes a preparation step of preparing a β-sialon phosphor, and an alkali treatment step of subjecting the surface of the β-sialon phosphor to alkali treatment.

[0026] The preparation step for preparing the β-sialon phosphor may be performed by a known method, but may also include, for example, a firing step of mixing raw material powders containing silicon, aluminum, and europium and firing the mixture to obtain a fired product, and at least one or more post-treatment steps of subjecting the fired product to a crushing / pulverization treatment, classification treatment, annealing treatment, acid treatment, etc. The post-treatment steps can be performed in any order. The alkali treatment step may be carried out after the classification treatment, or after the acid treatment.

[0027] The firing temperature in the firing step is, for example, 1800°C or higher and 2100°C or lower, preferably 1850°C or higher and 2050°C or lower. By setting the firing temperature to the above lower limit or higher, the luminescence intensity can be improved. The firing step may be performed multiple times. In addition, when firing is performed for the second or subsequent times, part of the raw materials may be added.

[0028] The ambient temperature during the annealing step is, for example, 1100°C or higher and 1800°C or lower, preferably 1300°C or higher and 1750°C or lower. By setting the annealing temperature to the above lower limit or higher, the emission intensity can be improved. By setting the annealing temperature to the above upper limit or lower, the crystallinity can be improved and a decrease in the emission peak intensity can be suppressed.

[0029] The atmospheric gas used in the annealing step is selected from the group consisting of a rare gas of an element in Group 18 of the periodic table, such as argon gas, an inert gas, such as nitrogen gas, hydrogen gas, and a mixed gas of hydrogen gas and argon gas.

[0030] The annealing process's improved properties are achieved over a wide range of atmospheric pressures, from reduced pressure to increased pressure, but pressures lower than 1 kPa are undesirable because they accelerate the decomposition of the β-sialon phosphor. Furthermore, by increasing the atmospheric pressure, it is possible to broaden the range of other conditions required to achieve the annealing effect (lower temperature, shorter time), but if the atmospheric pressure is too high, the annealing effect will plateau and a specialized, expensive annealing device will be required. Therefore, considering mass production, the preferred atmospheric pressure is 10 MPa or less, and more preferably less than 1 MPa.

[0031] If the treatment time in the annealing step is too short, the effect of improving crystallinity is low, and if it is too long, the annealing effect reaches a plateau, so the treatment time is from 1 hour to 24 hours, preferably from 2 hours to 10 hours.

[0032] Furthermore, the manufacturing method of this embodiment may include an acid treatment step of immersing the β-sialon phosphor in an acid solution after the annealing step, which can further improve the properties of the phosphor.

[0033] The acid treatment step preferably includes a step of immersing the β-sialon phosphor in an acid solution, separating the β-sialon phosphor from the acid using a filter or the like, and washing the separated β-sialon phosphor with water. The acid treatment can remove decomposition products of the β-sialon phosphor crystals that occur during the annealing step, thereby improving the fluorescent properties. Examples of acids used in the acid treatment include hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid, either singly or in combination. A mixed acid consisting of hydrofluoric acid and nitric acid is preferred, as it is suitable for removing decomposition products. The temperature of the acid solution during the acid treatment can be room temperature, but it is preferable to heat it to between 50°C and 90°C to enhance the effectiveness of the acid treatment.

[0034] In this manner, a β-sialon phosphor containing europium in solid solution can be obtained. If necessary, known processes may be added, such as post-treatments such as crushing / disintegration, purification, drying, sieving / classification, etc. The step of adjusting the particle size, such as sieving or classification, may be carried out at any time after the firing step, the annealing step, or the acid treatment step.

[0035] In the alkali treatment step, the β-sialon phosphor is heated in a state in which a solid basic substance is attached to the surface.

[0036] Examples of basic substances include alkali metal hydroxides, alkali metal carbonates, hydroxides of Group 2 elements of the periodic table, oxides of Group 2 elements of the periodic table, and quaternary ammonium. An example of the basic substance includes one or more selected from the group consisting of NaOH, KOH, LiOH, CaO, SrO, Na2CO3, and NaHCO3.

[0037] The solid basic substance may be a basic substance that is solid at room temperature, or may be a basic solution prepared by dissolving a basic substance in a solvent such as water and then removing the solvent at a temperature below 50° C. to dry the basic substance. For example, the basic substance may be vacuum dried at a temperature below 50° C.

[0038] To attach a solid basic substance to the surface, for example, a powder of β-sialon phosphor may be mixed with a basic substance that is solid at room temperature. Alternatively, a mixed solution containing a powder of a β-sialon phosphor, a basic substance, and water may be vacuum-dried at a temperature below 50°C to remove the water from the basic substance and adhere the solid basic substance to the surface of the β-sialon phosphor. By removing the solvent such as water at a relatively low temperature below 50°C, the Si-OH groups on the surface of the β-sialon phosphor can be suppressed.

[0039] During the alkali treatment step, the β-sialon phosphor is heated with the solid basic substance attached to its surface in an environment substantially free of water. The absence of water means that moisture (humidity) contained in the exposure atmosphere outside the solid basic substance is allowed, or moisture in hydrates contained in the solid basic substance is allowed.

[0040] In the alkali treatment step, the β-sialon phosphor can be heated from room temperature. Room temperature may be, for example, 23°C or 25°C. The upper limit of the heating temperature is not particularly limited, but may be, for example, 400°C or lower, or 450°C or lower.

[0041] In the alkali treatment step, heating may be performed from room temperature at a temperature rise rate of, for example, 0.1°C / min to 100°C / min, preferably 5°C / min to 50°C / min, and more preferably 1°C / min to 30°C / min.

[0042] In the alkali treatment step, the heating atmosphere may be, for example, an air atmosphere, a vacuum atmosphere, or an inert gas atmosphere such as a rare gas atmosphere or nitrogen atmosphere.

[0043] The method for producing a β-sialon phosphor of this embodiment may further include, after the alkali treatment step, a step of washing the obtained β-sialon phosphor with water. The water used for washing is removed by drying using a known method. After the alkali treatment step, post-treatments such as crushing / disintegration, refining, drying, sieving / classification, etc. may be carried out as necessary.

[0044] [Wavelength converter, light-emitting component] The light-emitting component of this embodiment comprises a light-emitting element and a wavelength converter that converts light irradiated from the light-emitting element and emits light, and the wavelength converter has the above-mentioned β-sialon phosphor.

[0045] An example of the method for manufacturing a wavelength conversion member of the present embodiment includes a step of manufacturing a wavelength conversion member using a β-sialon phosphor obtained by the method for manufacturing a β-sialon phosphor.

[0046] The wavelength converter of this embodiment converts light irradiated from a light-emitting element to emit light, and includes the above-mentioned 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. Known base materials can be used, such as glass, resin, and inorganic materials.

[0047] The shape of the wavelength converter 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.

[0048] [Light-emitting device]

[0049] The light emitting device according to this embodiment includes a light emitting member including a light source (light emitting element) and the wavelength converter. By combining a light source with a wavelength converter, it is possible to emit light with high luminous intensity.

[0050] An example of a method for manufacturing a light emitting device according to this embodiment includes a step of mounting a wavelength conversion member obtained by the method for manufacturing a wavelength conversion member on a light emitting surface of a light source.

[0051] 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 emit light with a wavelength of 300 nm to 500 nm, which is near ultraviolet to blue light. The LED chip and the lead frame may be electrically connected by bonding wires. The wavelength converter may be covered with a cap made of synthetic resin.

[0052] The wavelength converter may contain the β-sialon phosphor, but may also contain other phosphors. Examples of other phosphors include an α-sialon phosphor, a KSF phosphor, a CASN phosphor, a SCASN phosphor, and a YAG phosphor. These phosphors may be used alone or in combination of two or more.

[0053] In the case of a light-emitting device using the above-mentioned 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, the light emits green light with a peak wavelength in the range of 520 nm or more and 560 nm or less. Therefore, by combining a near-ultraviolet LED chip or a blue LED chip and a β-sialon phosphor as a light source with one or more red-, blue-, yellow-, or orange-emitting phosphors, it is possible to produce white light.

[0054] For example, a combination of a β-sialon phosphor that exhibits green color and a KSF-based phosphor that exhibits red color can be used favorably in LEDs for backlights suitable for TVs with high color rendering. Below, examples of reference forms are given. 1. A preparation step of mixing raw material powders containing silicon, aluminum, and europium, and firing the mixture to prepare a β-sialon phosphor containing europium in solid solution; an alkali treatment step of heating the β-sialon phosphor with a solid basic substance attached to its surface; A method for producing a β-sialon phosphor, comprising: 2. A method for producing the β-sialon phosphor of 1., The method for producing a β-sialon phosphor, wherein the alkali treatment step involves heating from room temperature. 3. A method for producing the β-sialon phosphor according to 2., In the alkali treatment step, the material is heated from room temperature at a temperature increase rate of 0.1°C / min to 100°C / min. 4. A method for producing the β-sialon phosphor according to any one of 1. to 3., In the alkali treatment step, the heating atmosphere is an air atmosphere, a vacuum atmosphere, a rare gas atmosphere, or a nitrogen gas atmosphere. 5. A method for producing the β-sialon phosphor according to any one of 1. to 4., The method for producing a β-sialon phosphor further comprises, after the alkali treatment step, a step of washing the obtained β-sialon phosphor with water. 6. A method for producing the β-sialon phosphor according to any one of 1. to 5., The solid basic substance is NaOH, KOH, LiOH, CaO, SrO, Na 2 CO 3 , and NaHCO 3 The method for producing a β-sialon phosphor includes one or more selected from the group consisting of: 7. A method for producing a wavelength conversion member, comprising the step of producing a wavelength conversion member using a β-sialon phosphor obtained by the method for producing a β-sialon phosphor according to any one of 1. to 6. 8. A method for manufacturing a light emitting device, comprising the step of mounting a wavelength conversion member obtained by the method for manufacturing a wavelength conversion member according to 7. on a light emitting surface of a light source. [Example]

[0055] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0056] <Preparation of β-SiAlON phosphor>

[0057] (Comparative Example 1) (1) The raw materials were weighed into a container so that silicon nitride (Si3N4) was 98.4% by mass, aluminum nitride (AlN) was 1.0% by mass, and europium oxide (Eu2O3) was 0.6% by mass, and mixed using a V-type mixer (manufactured by Tsutsui Scientific Machinery Co., Ltd.) to obtain a mixture. The obtained mixture was passed through a sieve with 250 μm openings to remove aggregates, thereby obtaining a raw material composition. The aggregates that did not pass through the sieve were crushed, and the particle size was adjusted so that they would pass through the sieve.

[0058] (2) 200 g of the raw material composition prepared as described above was weighed into a cylindrical boron nitride container with a lid (a molded product made by Denka Co., Ltd., primarily composed of boron nitride (trade name: Denka Boron Nitride N-1), inner diameter: 10 cm, height: 10 cm). The container was then placed in an electric furnace equipped with a carbon heater, heated to 2000°C under a nitrogen gas atmosphere (pressure: 0.90 MPaG), and heated at 2000°C for 10 hours (firing step). After heating, the sample that had become loosely agglomerated in the container was placed in a mortar and crushed. After crushing, the sample was passed through a sieve with 250 μm openings to obtain a powdery first fired body.

[0059] (3) Next, the first fired body was packed into a cylindrical boron nitride container, and the container was placed in an electric furnace equipped with a carbon heater. The temperature was raised to 1450°C in an argon gas atmosphere (pressure: 0.025 MPaG), and heating was continued at 1450°C for 5 hours (annealing step). After heating, the loosely aggregated particles in the container were crushed in a mortar and mortar, and then passed through a 250 μm sieve to obtain powder.

[0060] (4) Next, the powder obtained in (3) was added to a mixed acid of hydrofluoric acid (concentration: 50% by mass) and nitric acid (concentration: 70% by mass) (a 1:1 volume ratio of hydrofluoric acid and nitric acid), and acid treatment was performed for 30 minutes while stirring at 75°C. After the acid treatment, the stirring was stopped, the powder was allowed to settle, and the supernatant and fine powder refined by the acid treatment were removed. Distilled water was then added and the mixture was stirred again. The stirring was stopped, the powder was allowed to settle, and the supernatant and fine powder were removed. This procedure was repeated until the pH of the aqueous solution was 8 or less and the supernatant was transparent. The resulting precipitate was filtered, dried, and passed through a sieve with 250 μm openings, yielding a europium-activated β-sialon phosphor of Comparative Example 1.

[0061] (Comparative Example 2) In the same manner as in Comparative Example 1, the powder of β-type sialon phosphor obtained in (4) was heated in an air atmosphere at a heating rate of 10°C / min, heated at 105°C for 10 hours (heating step), and passed completely through a sieve with 250 μm openings to obtain the europium-activated β-type sialon phosphor of Comparative Example 2.

[0062] (Comparative Example 3) A europium-activated β-sialon phosphor of Comparative Example 3 was obtained in the same manner as in Comparative Example 2, except that the heating temperature in the heating step was changed to 175° C. and the heating time was changed to 1 hour.

[0063] Comparative Example 4 In the same manner as in Comparative Example 1, the powder of the β-type sialon phosphor obtained in (4) was mixed with a 50% by mass aqueous solution of sodium hydroxide, and then the mixed solution was filtered. After filtration, the mixed solution was kept at 30°C for 1 day in a vacuum atmosphere without heating, and then washed with water to remove any basic substances remaining on the surface. The mixture was then dried and passed through a sieve with an opening of 250 μm to obtain the europium-activated β-type sialon phosphor of Comparative Example 4.

[0064] (Comparative Example 5) In the same manner as in Comparative Example 1, the powder of the β-type sialon phosphor obtained in (4) was mixed with a 50 mass% aqueous sodium hydroxide solution, and then the mixed solution was heated in an air atmosphere at a heating rate of 10°C / min, heated at 100°C for 1 hour (heating step), washed with water to remove any basic substances remaining on the surface, dried, and passed through a sieve with a mesh size of 250 μm to obtain the europium-activated β-type sialon phosphor of Comparative Example 5.

[0065] (Comparative Example 6) A europium-activated β-sialon phosphor of Comparative Example 6 was obtained in the same manner as in Comparative Example 5, except that the heating temperature in the heating step was changed to 200°C.

[0066] (Comparative Example 7) A europium-activated β-sialon phosphor of Comparative Example 7 was obtained in the same manner as in Comparative Example 5, except that the heating temperature in the heating step was changed to 300°C.

[0067] (Comparative Example 8) In the same manner as in Comparative Example 1, the powder of the β-type sialon phosphor obtained in (4) was mixed with a 40% by mass aqueous solution of sodium chloride (aqueous solution of a non-basic substance), and then the mixed solution was filtered. The residue was vacuum dried at 45°C to obtain a dried powder, which was then heated at a rate of 10°C / min and heated to 300°C for 1 hour (heating step), washed with water, dried, and passed through a sieve with a mesh size of 250 μm to obtain the europium-activated β-type sialon phosphor of Comparative Example 8.

[0068] (Comparative Example 9) In the same manner as in Comparative Example 1, the powder of the β-type sialon phosphor obtained in (4) was mixed with a 20 mass% aqueous sodium hydroxide solution, and the mixed solution was heated at 70°C for 3 hours in an air atmosphere. The slurry-like residue was then continuously heated at 200°C for 2 hours (heating step), washed with water, dried, and passed through a sieve with a mesh size of 250 μm to obtain the europium-activated β-type sialon phosphor of Comparative Example 9. It was confirmed that water remained in the slurry residue after heating at 70°C for 3 hours.

[0069] Example 1 In the same manner as in Comparative Example 1, the powder of the β-type sialon phosphor obtained in (4) was mixed with a 50% by mass aqueous solution of sodium hydroxide, and then the mixed solution was filtered. The residue was vacuum dried at 45°C to obtain a dried powder, which was then heated in a vacuum atmosphere at 45°C for 10 hours (alkali treatment step), washed with water, dried, and passed through a sieve with a mesh size of 250 μm to obtain the europium-activated β-type sialon phosphor of Example 1.

[0070] Example 2 A europium-activated β-sialon phosphor of Example 2 was obtained in the same manner as in Example 1, except that in the alkali treatment step, instead of "heating at 45°C for 10 hours in a vacuum atmosphere," the obtained dry powder was heated in an air atmosphere from 25°C at a heating rate of 10°C / min and then heated to 100°C for 1 hour.

[0071] (Examples 3 to 16 and 19) Europium-activated β-sialon phosphors of Examples 3 to 16 and 19 were obtained in the same manner as in Example 2, except that the conditions in the alkali treatment step were changed to those shown in Table 1. Examples 17 and 18 Powdered Na2CO3 or NaHCO3 was mixed with the powder of the β-type sialon phosphor obtained in (4) in the same manner as in Comparative Example 1 to obtain a powdered mixture (dry powder). The obtained powdered mixture was heated in an air atmosphere from 25°C at a heating rate of 10°C / min to 300°C for 1 hour, then washed with water, dried, and passed through a sieve with a mesh size of 250 μm to obtain the europium-activated β-type sialon phosphors of Examples 17 and 18.

[0072] [Table 1]

[0073] The β-sialon phosphors of each example and comparative example were evaluated for the following characteristics and evaluation items.

[0074] (Diffuse reflectance before and after thermal degradation test) The diffuse reflectance of the β-sialon phosphor was measured using an ultraviolet-visible spectrophotometer (V-550) manufactured by JASCO Corporation equipped with an integrating sphere device (ISV-469). Baseline correction was performed using a standard reflector (Spectralon), a solid sample holder filled with β-type sialon phosphor was set, and diffuse reflectance was measured in the wavelength range of 500 to 850 nm. The diffuse reflectance (%) at 500 nm was measured. Furthermore, 4 g of the β-sialon phosphor was placed in a porcelain crucible with a lid (Kennis, capacity 30 mL), the lid was closed, and a heat treatment (thermal degradation test) was carried out in an air atmosphere at 250°C for 5 hours (heat increase rate 10°C / min). After that, the sample was passed through a sieve with 250 μm openings, and the diffuse reflectance (%) at 500 nm was measured in the same manner. Table 1 shows the diffuse reflectance (%) at 500 nm before and after the thermal degradation test.

[0075] The measured values ​​of 500 nm diffuse reflectance may vary depending on the manufacturer of the measuring device, the production lot number, etc. Therefore, the values ​​measured by the measurement method described in this specification are used as various measured values. However, when the manufacturer of the measuring device, the production lot number, etc. is changed, each measured value can be corrected using the measured value of a standard sample of β-sialon phosphor as the reference value.

[0076] When the 500 nm diffuse reflectance of a standard sample of β-sialon phosphor (manufactured by Sialon Corporation, NIMS Standard Green lot No. NSG1301) was measured in accordance with the above-mentioned measurement method, the 500 nm diffuse reflectance was found to be 80.4%.

[0077] From the above, the β-sialon phosphors of Examples 1 to 19 showed higher diffuse reflectance after the thermal degradation test than those of Comparative Examples 1 to 9, and therefore showed superior resistance to thermal degradation.

[0078] <Reliability test> The reliability of the LED packages incorporating the alkali-treated phosphor particles of each example and the phosphor particles of each comparative example was evaluated as follows: The results of the reliability test are shown in FIG. The LED package used was one conforming to the structure of the light emitting device shown in Figure 1. The alkali-treated phosphor particles or phosphor particles were mounted on the LED package by wire-bonding the lead frame to the electrode on the top of the LED located at the bottom of the recessed case, and then injecting the alkali-treated phosphor particles or phosphor particles mixed with liquid silicone resin (KER6150, Shin-Etsu Chemical Co., Ltd.) into the recessed case using a microsyringe. The phosphor concentration in the phosphor + resin was 10.5 wt%. After mounting the alkali-treated phosphor particles or phosphor particles, the LED was left to stand in a room temperature, low humidity environment (MacDry MCU-201A, ERC Co., Ltd.) for 15 hours, and then cured at 150°C for 1 hour. The LED used had a peak emission wavelength of 448 nm and a chip size of 1.0 mm x 0.5 mm. The luminous flux of the LED packages incorporating the alkali-treated phosphor particles of each example and the phosphor particles of each comparative example obtained in the above manner was measured and designated as the initial value L0. Furthermore, the LED packages were left for 250 hours with a current of 300 mA applied at 85°C and 85% RH, then removed and dried at room temperature. The luminous flux L1 was measured and the reliability coefficient M (= L1 / L0 × 100) was calculated. The reliability test requires a reliability coefficient M of 80% or higher. This value can only be achieved with highly reliable alkali-treated phosphor particles. It was confirmed that the LED packages incorporating the alkali-treated phosphor particles of Examples 3 and 4 met the above-mentioned pass criteria. [Explanation of symbols]

[0079] 10 Light-emitting device 20 Light-emitting element 30 Heatsink 40 cases 50 First lead frame 60 Second lead frame 70 Bonding Wire 72 Bonding Wire 80 Complex 82 Alkali-treated phosphor particles 84 Encapsulating material

Claims

1. a preparation step of preparing a β-sialon phosphor containing europium as a solid solution, the preparation step including a firing step of mixing raw material powders containing silicon, aluminum, and europium and firing the mixture to obtain a fired product, and a post-treatment step of further performing at least one of a crushing / pulverizing treatment, a classification treatment, an annealing treatment, and an acid treatment on the fired product after the firing step; an alkali treatment step of heating the β-sialon phosphor with a solid basic substance attached to its surface; A method for producing a β-sialon phosphor, comprising:

2. A method of manufacturing a phosphor comprising: a preparation step of mixing raw material powders containing silicon, aluminum, and europium, and firing the mixture to prepare a β-sialon phosphor containing europium as a solid solution; an alkali treatment step of heating the β-sialon phosphor with a solid basic substance attached to the surface thereof, The method for producing a β-sialon phosphor is represented by the general formula Si 6-z Al z O z N 8-z :Eu 2+ (0<z≦4.2).

3. A method of manufacturing a phosphor comprising the steps of: mixing raw material powders containing silicon, aluminum, and europium; and firing the mixture to prepare a β-sialon phosphor containing europium in a solid solution; an alkali treatment step of heating the β-sialon phosphor with a solid basic substance attached to the surface thereof, In the alkali treatment step, the heating temperature is 450° C. or less.

4. A method for producing the β-sialon phosphor according to any one of claims 1 to 3, The method for producing a β-sialon phosphor, wherein the alkali treatment step involves heating from room temperature.

5. A method for producing the β-sialon phosphor according to any one of claims 1 to 4, In the alkali treatment step, the temperature is increased from room temperature at a rate of 0.1° C. / min to 100° C. / min.

6. A method for producing the β-sialon phosphor according to any one of claims 1 to 5, In the alkali treatment step, the heating atmosphere is an air atmosphere, a vacuum atmosphere, a rare gas atmosphere, or a nitrogen gas atmosphere.

7. A method for producing the β-sialon phosphor according to any one of claims 1 to 6, The method for producing a β-sialon phosphor further comprises, after the alkali treatment step, a step of washing the obtained β-sialon phosphor with water.

8. A method for producing the β-sialon phosphor according to any one of claims 1 to 7, The solid basic substance is NaOH, KOH, LiOH, CaO, SrO, Na ２ CO ３ , and NaHCO ３ The method for producing a β-sialon phosphor includes one or more selected from the group consisting of:

9. A method for producing a wavelength conversion member, comprising a step of producing a wavelength conversion member using a β-sialon phosphor obtained by the method for producing a β-sialon phosphor according to any one of claims 1 to 8.

10. A method for manufacturing a light emitting device, comprising the step of mounting a wavelength conversion member obtained by the method for manufacturing a wavelength conversion member according to claim 9 on a light emitting surface of a light emitting source.

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