Phosphor powder and light-emitting device

Abstract

The phosphor powder of the present invention contains alpha-sialon phosphor particles, and satisfies a repose angle of 55 DEG or less and a tap bulk density of 0.95 g / cm3 or less as determined by an injection-limited bottom surface method.

Description

Technical Field

[0001] The present invention relates to a phosphor powder and a light-emitting device. Background Art

[0002] Known as nitride and oxynitride phosphors, α-sialon phosphors activated by specific rare earth elements have useful fluorescence characteristics and are suitable for white LEDs and the like. In the α-sialon phosphor, part of the Si-N bonds of the α-silicon nitride crystal is replaced by Al-N bonds and Al-O bonds, and in order to maintain electrical neutrality, it has a structure in which specific elements (Ca and Li, Mg, Y, or lanthanide metals other than La and Ce) penetrate and dissolve in the lattice. By making part of the elements that penetrate and dissolve into the lattice be rare earth elements that become luminescence centers, fluorescence characteristics are exhibited. Among them, an α-sialon phosphor in which Ca is dissolved and part of it is replaced by Eu is excited relatively efficiently in a wide wavelength region from ultraviolet to blue and exhibits yellow to orange light emission.

[0003] As such a technique, for example, the technique described in Patent Document 1 is known. Patent Document 1 describes an α-sialon phosphor powder having a tapped bulk density of 1.00 g / cm 3 or more and 1.80 g / cm 3 or less after 50 taps (Claim 1 of Patent Document 1, etc.).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: International Publication No. 2019 / 188630 Summary of the Invention

[0007] However, as a result of the study by the present inventors, it was found that there is room for improvement in the metering stability of the α-sialon phosphor powder described in Patent Document 1 above.

[0008] As a result of further study by the present inventors, it was found that with respect to a phosphor powder containing α-sialon phosphor particles, by reducing the tapped bulk density to below a specified value, the deviation in the feed amount when filling into a container during heat treatment, when filling the product into a bottle, when feeding into a dry classifier or a jet mill, etc. becomes smaller. As a result of further in-depth research based on this insight, it was found that even in a phosphor powder having a tapped bulk density below a specified value, by setting the angle of repose based on the injection-limited bottom method to below a specified value, it is possible to further suppress the deviation in the feed amount and improve the metering stability, and thus the present invention was completed.

[0009] According to one aspect of the present invention, the following phosphor powder and light-emitting device can be provided.

[0010] 1. A phosphor powder comprising α - sialon phosphor particles, wherein,

[0011] The angle of repose of the phosphor powder measured by the following step A based on the injection - defined bottom method is 55° or less,

[0012] The tapped bulk density of the phosphor powder measured by the following step B is 0.95 g / cm 3 or less.

[0013] (Step A)

[0014] Prepare a frustum of a cone with a bottom surface having a diameter of φ33 mm and a hose with a front - end port having an inner diameter of 4φ mm, and fix the hose such that the front - end port is at a height of 40 mm from the bottom surface.

[0015] Supply the phosphor powder as a measurement sample into the hose, and let it continuously and freely fall from the front - end port towards the center of the bottom surface until the measurement sample becomes a state of stably overflowing from the bottom surface.

[0016] Then, find the elevation angle formed between the side surface of the conical deposit of the measurement sample formed on the bottom surface and the bottom surface, and set this elevation angle as the angle of repose (°) based on the injection - defined bottom method.

[0017] (Step B)

[0018] Install an auxiliary cylinder on a dry cylindrical measuring container of a specified volume, and introduce the phosphor powder as a measurement sample into the interior of the measuring container through the auxiliary cylinder. For the measuring container with the auxiliary cylinder, tap it 50 times in the vertical direction at 50 - 60 times per minute under the condition of a stroke of 2 cm. After tapping, remove the auxiliary cylinder, scrape off the excess measurement sample from the upper surface of the measuring container, and measure the total mass. Subtract the mass of the empty cylindrical container measured in advance from the total mass to measure the mass of the measurement sample filled in the measuring container. Divide the mass (g) of the filled measurement sample by the internal volume (cm 3 ) of the measuring container to obtain the measured value. Set the average value of the three measured values as the above - mentioned tapped bulk density (g / cm 3 ).

[0019] 2. The phosphor powder according to 1., wherein,

[0020] The angle of repose is 20° or more.

[0021] 3. The phosphor powder according to 1. or 2., wherein,

[0022] The tapped bulk density is 0.30 g / cm 3 or more.

[0023] 4. The phosphor powder according to any one of 1. to 3., which contains inorganic fine particles.

[0024] 5. The phosphor powder according to 4., wherein

[0025] the content of the inorganic fine particles is 0.005% by mass or more and 10% by mass or less in 100% by mass of the phosphor powder.

[0026] 6. The phosphor powder according to 4. or 5., wherein

[0027] the average particle diameter of the inorganic fine particles is 10 μm or less.

[0028] 7. The phosphor powder according to any one of 4. to 6., wherein

[0029] the inorganic fine particles contain at least one selected from the group consisting of metal oxide particles and metal hydroxide particles.

[0030] 8. The phosphor powder according to any one of 4. to 7., wherein

[0031] the primary particles of the inorganic fine particles and / or aggregates of the primary particles are attached to a part of the surface of the α-sialon phosphor particles.

[0032] 9. The phosphor powder according to any one of 1. to 8., wherein

[0033] in the volume frequency particle size distribution measured by the wet type laser diffraction scattering method, the particle diameter at which the cumulative value becomes 5% from the small particle size side is defined as D5, the particle diameter at which the cumulative value becomes 50% is defined as D 50 and the particle diameter at which the cumulative value becomes 97% is defined as D 97 when,

[0034] (D 97 -D5) / D 50 is 2.0 or more and 5.0 or less.

[0035] 10. A light-emitting device, comprising:

[0036] a light-emitting light source; and

[0037] a wavelength conversion member,

[0038] the wavelength conversion member contains the phosphor powder according to any one of 1. to 9.

[0039] According to the present invention, a phosphor powder having excellent metering stability and a light-emitting device using the phosphor powder can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a cross-sectional view schematically showing an example of the structure of the light-emitting device.

[0041] Figure 2 is a schematic view for explaining a method of measuring the angle of repose based on the injection-limited bottom method.

[0042] Figure 3 is a schematic view for explaining the feeding test. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in all the drawings, the same reference numerals are assigned to the same components, and the description will be appropriately omitted. And, the drawings are schematic views and do not match the actual dimensional ratios.

[0044] The outline of the phosphor powder of the present embodiment will be described.

[0045] The phosphor powder of the present embodiment contains α-sialon phosphor particles and is configured to satisfy the following: the angle of repose of the phosphor powder based on the injection-limited bottom method measured according to the following step A is 55° or less, and the tapped bulk density of the phosphor powder measured according to the following step B is 0.95 g / cm 3 Hereinafter.

[0046] Step A for measuring the angle of repose based on the injection-limited bottom method is as follows.

[0047] Prepare a frustum of a cone having a bottom surface with a diameter of φ33 mm and a hose having a front end port with an inner diameter of 4φ mm, and fix the hose so that the front end port is at a height of 40 mm from the bottom surface.

[0048] Supply the phosphor powder as a measurement sample into the hose, and let it continuously fall freely from the front end port of the hose toward the center of the bottom surface of the frustum of a cone until the measurement sample becomes a state of stably overflowing from the bottom surface.

[0049] Then, find the elevation angle (θ) formed between the side surface of the conical deposit of the measurement sample formed on the bottom surface of the frustum of a cone and the bottom surface of the frustum of a cone, and set this elevation angle as the above-mentioned angle of repose (°) based on the injection-limited bottom method.

[0050] Step B for measuring the tapped bulk density is as follows.

[0051] An auxiliary cylinder is installed on a cylindrical measuring container with a specified dry capacity, and the phosphor powder is introduced as a measurement sample into the interior of the measuring container through the auxiliary cylinder. For the measuring container with the auxiliary cylinder, it is gently tapped 50 times in the vertical direction at 50 - 60 times per minute under the condition of a stroke of 2 cm. After tapping, the auxiliary cylinder is removed, and the excess measurement sample is scraped off from the upper surface of the measuring container, and the overall mass is measured. The mass of the empty cylindrical container measured in advance is subtracted from the overall mass to measure the mass of the measurement sample filled into the measuring container. The mass (g) of the filled measurement sample is divided by the internal volume (cm 3 ) to obtain the measured value. The average value of the three measured values is set as the above-mentioned tapped bulk density (g / cm 3 ).

[0052] In the present embodiment, the upper limit of the tapped bulk density of the phosphor powder is 0.95 g / cm 3 or less, preferably 0.80 g / cm 3 or less, more preferably 0.75 g / cm 3 or less, and even more preferably 0.70 g / cm 3 or less. Moreover, the upper limit of the angle of repose of the phosphor powder based on the injection-limited bottom method is 55° or less, preferably 53° or less, and more preferably 51° or less. Thereby, the metering stability can be improved.

[0053] According to the insight of the present inventor, it has been found that both the tapped bulk density and the angle of repose based on the injection-limited bottom method are required as indices for stably determining the deviation of the conveying amount / conveying speed in the feeding test (during vibratory conveying). And in the injection-limited bottom method, it is different from other injection methods in terms of the condition of limiting the area of the bottom surface on which the measurement sample is piled up. However, since the piled-up material can stably form a conical shape, the deviation of the measured value of the angle of repose during repeated measurements is suppressed, so it is more preferable. In the case of a slightly aggregated cohesive powder, etc. in injection methods other than the injection-limited bottom method, the inclination of the piled-up material is locally elongated at the bottom of the piled-up material due to the rolling of powders such as aggregates, and the bottom of the piled-up material does not expand isotropically, and it is highly possible that the piled-up material does not become a conical shape. However, in the bottom surface limiting method, aggregates as described above are excluded, so it is easy to form a conical shape and can be measured more accurately.

[0054] By using the phosphor powder of the present embodiment, it is possible to suppress the deviation of the conveying amount caused by a feeder or the like. That is, it is possible to suppress the following situation: even when conveying under the same conveying conditions, the measured value of the phosphor powder changes every time. As a result, the accuracy of the filling amount during container filling is improved, the accuracy of the feeding amount during dry classification or jet mill pulverization is improved, the deviation of the classification efficiency or pulverization efficiency can be suppressed, and the accuracy is improved. Moreover, the adhesion in the pipe or on the hopper is reduced, bridging and the like are suppressed, and the conveying is facilitated.

[0055] Moreover, the lower limit of the angle of repose based on the injection-limited bottom method is, for example, 20° or more, preferably 25° or more, more preferably 30° or more, and further preferably 34° or more. Thereby, the concentration of the phosphor in the mixture can be maintained, and the fluorescence characteristics can be utilized. And the possibility of leakage or outflow from the container or the inlets of a dry classifier, a jet mill, etc. due to excessive fluidity is reduced.

[0056] Moreover, the lower limit of the tapped bulk density is, for example, 0.30 g / cm 3 or more, preferably 0.35 g / cm 3 or more, more preferably 0.40 g / cm 3 or more. Thereby, since the volume is not too large, it can be effectively dispersed in the resin when dispersed in the resin during the production of an LED.

[0057] Moreover, in another mode, in the phosphor powder, when measuring the volume frequency particle size distribution by the wet laser diffraction scattering method, the particle size at which the cumulative value becomes 5% from the small particle size side is defined as D5, and the particle size at which the cumulative value becomes 50% is defined as D 50 , and the particle size at which the cumulative value becomes 97% is defined as D 97 .

[0058] As another mode, the phosphor powder can be configured such that (D 97 -D5) / D 50 satisfies, for example, 2.0 or more and 5.0 or less.

[0059] (D 97 -D5) / D 50 The lower limit of is, for example, 2.0 or more, preferably 2.3 or more, and more preferably 2.5 or more. Thereby, there are many large particle size particles with a small specific surface area and less scattering or reflection, and the brightness can be improved when forming an LED.

[0060] (D 97 -D5) / D 50The upper limit is, for example, 5.0 or less, preferably 4.5 or less, more preferably 4.0 or less. Thus, there are fewer fine powders with a large specific surface area and increased scattering or reflection, and the brightness can be improved when forming an LED. Also, there are fewer coarse powders, and the metering deviation can be reduced when forming an LED.

[0061] In the present embodiment, for example, by appropriately selecting the types or blending amounts of the respective components contained in the phosphor powder, the preparation method of the phosphor powder, etc., it is possible to control the angle of repose, tapped bulk density, and particle size distribution based on the injection-limited bottom surface method. Among these, for example, as elements for setting the angle of repose, tapped bulk density, and particle size distribution based on the injection-limited bottom surface method within a desired numerical range, it is possible to cite performing appropriate classification / crushing / grinding treatment on α-sialon particles, adding a prescribed amount of inorganic fine particles to the α-sialon particles when necessary, and in this case, adjusting so that the tapped bulk density ratio represented by the tapped bulk density of the phosphor powder (α-sialon particles) / the tapped bulk density of the phosphor powder (α-sialon particles + inorganic fine particles) becomes about 0.5 to 1.6.

[0062] Hereinafter, each structure of the phosphor powder of the present embodiment will be described in detail.

[0063] The phosphor powder of the present embodiment contains α-sialon phosphor particles and, when necessary, also contains inorganic fine particles.

[0064] <α-sialon phosphor particles>

[0065] The α-sialon phosphor particles are particles composed of an α-sialon phosphor activated by an activating substance (for example, Eu).

[0066] The α-sialon phosphor activated by Eu may have a composition represented by the following general formula.

[0067] The above general formula is represented by (M1 x , M2 y , Eu z )(Si 12-(m+n) Al m+n )(O n N 16-n ) (wherein, M1 is a monovalent Li element, and M2 is one or more divalent elements selected from the group consisting of Mg, Ca, and lanthanide elements (excluding La and Ce)).

[0068] In the above general formula, m and n determined by x, y, z and their accompanying Si / Al ratio or O / N ratio satisfy

[0069] 0 ≤ x < 2.0,

[0070] 0 ≤ y < 2.0,

[0071] 0 < z ≤ 0.5,

[0072] 0 < x + y,

[0073] 0.3 ≤ x + y + z ≤ 2.0,

[0074] 0 < m ≤ 4.0 and

[0075] 0 < n ≤ 3.0.

[0076] In the above general formula, when Ca is used as M2, the α-sialon phosphor is stabilized within a wide compositional range, and a part of it is replaced with Eu that becomes a luminescence center, whereby a phosphor that emits visible light from yellow to orange when excited by light in a wide wavelength region from ultraviolet to blue can be obtained.

[0077] As the crystal phase of the α-sialon phosphor, an α-sialon single phase is preferred, and other crystal phases such as aluminum nitride or its polytypes may also be included.

[0078] However, generally, the α-sialon phosphor sometimes cannot strictly define the solid solution composition by compositional analysis or the like due to a second crystal phase having a different solid solution composition from that of the α-sialon phosphor or an amorphous phase that inevitably exists.

[0079] The α-sialon phosphor particles include massive secondary particles formed by sintering a plurality of equiaxed primary particles. The primary particles in the present embodiment refer to solids having a clear boundary that cannot be further identified when observed with an electron microscope or the like as primary particles. The particles constituting the powder or aggregate are called primary particles. Therefore, single crystals, polycrystals, amorphous substances, etc. may sometimes become primary particles.

[0080] The shape of the α-sialon phosphor particles is not particularly limited, and examples include spherical bodies, cubes, columnar bodies, irregular shapes, etc.

[0081] Here, a method for manufacturing the α-sialon phosphor particles according to the embodiment will be described.

[0082] In the α-sialon phosphor particles, during the synthesis process, mainly a part of the raw material powder reacts to form a liquid phase, and each element moves through this liquid phase, thereby forming a solid solution and growing crystal grains.

[0083] First, raw materials containing elements constituting α - sialon phosphor particles, which contain Eu, are mixed. Specifically, in α - sialon phosphor particles with a low oxygen content synthesized using calcium nitride as the calcium raw material, calcium is dissolved at a high concentration. In particular, when the Ca solid - solution concentration is high, a phosphor with an emission peak wavelength on the longer - wavelength side (590 nm or more) than that of the conventional composition using oxide raw materials can be obtained. Specifically, in the general formula, it is preferably 1.5 < x + y+z ≤ 2.0. A part of Ca can also be replaced with Li, Mg, Sr, Ba, Y, and lanthanide elements (except La and Ce) to finely adjust the emission spectrum.

[0084] As raw material powders other than the above, silicon nitride, aluminum nitride, and Eu compounds can be cited. As Eu compounds, there are europium oxide, compounds that become europium oxide after heating, and europium nitride. Europium nitride, which can reduce the amount of oxygen in the system, is preferred.

[0085] If pre - synthesized α - sialon phosphor particles are added to an appropriate amount of raw material powder, this will become the growth point of crystal grains, and α - sialon phosphor particles with a relatively large short - axis diameter can be obtained. The particle shape can be controlled by changing the morphology of the added α - sialon particles.

[0086] As methods for mixing the respective raw materials, there are a method of dry mixing and a method of wet - mixing in an inert solvent that does not substantially react with each component of the raw materials and then removing the solvent. As mixing devices, there are V - type mixers, rocking mixers, ball mills, and vibration mills. Regarding the mixing of calcium nitride, which is unstable in the atmosphere, since its hydrolysis or oxidation will affect the characteristics of the synthesized product, it is preferably carried out in a glove box in an inert environment.

[0087] The powder obtained by mixing (hereinafter, simply referred to as raw material powder) is filled into a container made of a material with low reactivity to the raw materials and the synthesized phosphor (for example, a boron nitride container), and heated for a specified time in a nitrogen environment to obtain α - sialon phosphor. The temperature of the heat treatment is preferably set to 1650 °C or higher and 1950 °C or lower.

[0088] By setting the heat - treatment temperature to 1650 °C or higher, the residual amount of unreacted products can be suppressed, and primary particles can grow sufficiently. And by setting the heat - treatment temperature to 1950 °C or lower, significant sintering between particles can be suppressed.

[0089] Regarding the heating time during the heat treatment, as a time range in which there are no adverse conditions such as a large amount of unreacted substances remaining, insufficient growth of primary particles, and sintering between particles, it is preferably 2 hours or more and 24 hours or less.

[0090] An α - sialon phosphor having an ingot shape is produced through the above - mentioned processes. For the ingot - shaped α - sialon phosphor, through a pulverization process using pulverizers such as crushers, mortars for pulverization, ball mills, vibration mills, jet mills, etc. and a sieving classification process after these pulverization treatments, a powder composed of α - sialon phosphor particles with the D 50 particle size of secondary particles adjusted can be obtained. And, by performing in the process of dispersing the powder in an aqueous solution to remove secondary particles with a small particle size and low precipitation tendency, the D 50 particle size of secondary particles can be adjusted. Classification can be performed using a cyclone separator, a liquid cyclone separator, a centrifuge, etc. that utilize centrifugal force.

[0091] The α - sialon phosphor particles according to the embodiment can be produced by performing an acid treatment process after performing the above - mentioned processes.

[0092] In the acid treatment process, for example, the α - sialon phosphor particles are immersed in an acidic aqueous solution. As the acidic aqueous solution, an acidic aqueous solution containing one acid selected from acids such as hydrofluoric acid, nitric acid, hydrochloric acid, etc., or a mixed acid aqueous solution obtained by mixing two or more of the above - mentioned acids can be cited. Among them, a hydrofluoric acid aqueous solution containing only hydrofluoric acid and a mixed acid aqueous solution obtained by mixing hydrofluoric acid and nitric acid are more preferable. The stock solution concentration of the acidic aqueous solution can be appropriately set according to the strength of the acid used. For example, it is preferably 0.7% or more and 100% or less, more preferably 0.7% or more and 40% or less. And, the temperature during the acid treatment is preferably 25°C or more and 90°C or less, more preferably 60°C or more and 90°C or less. As the reaction time (immersion time), it is preferably 15 minutes or more and 80 minutes or less.

[0093] <Fine Particles>

[0094] In the inorganic fine particles in the phosphor powder, the primary particles and / or aggregates of primary particles can adhere to a part of the surface of the α - sialon phosphor particles. By making the inorganic fine particles adhere to the surface of the α - sialon phosphor particles, the angle of repose of the phosphor powder based on the injection - defined bottom method can be reduced.

[0095] The upper limit of the average particle size of the inorganic fine particles is, for example, 10 μm or less, preferably 5 μm or less, more preferably 1 μm or less, and further preferably 0.5 μm or less. Thereby, the angle of repose of the phosphor powder based on the injection - defined bottom method can be increased.

[0096] The lower limit of the above - mentioned average particle size is not particularly limited and can be, for example, 1 nm or more.

[0097] The average particle diameter of the inorganic fine particles can be measured, for example, by a transmission electron microscope (TEM) or dynamic light scattering (DLS). Specifically, in the case of measurement by TEM, the equivalent circle diameters of 100 inorganic fine particles in the TEM image can be measured to obtain the number-based median diameter. Further, in the case of measurement by DLS, the volume-based median diameter can be obtained. Regarding the primary particle diameter, using a transmission electron microscope (TEM), 100 diameters of solids (particles constituting the powder or aggregate) with clear boundaries that cannot be further identified are measured as primary particles, and the number-based median diameter is obtained.

[0098] The lower limit of the content of the inorganic fine particles is, for example, 0.005% by mass or more, preferably 0.01% by mass or more, and more preferably 0.05% by mass or more in 100% by mass of the phosphor powder. Thereby, the angle of repose based on the injection-limited bottom method can be reduced.

[0099] The upper limit of the content of the inorganic fine particles is, for example, 10% by mass or less, preferably 8% by mass or less, and more preferably 6% by mass or less in 100% by mass of the phosphor powder. Thereby, the balance between the angle of repose and the tapped bulk density based on the injection-limited bottom method can be achieved.

[0100] Unlike the phosphor particles, the inorganic fine particles may contain at least one selected from the group consisting of metal oxide particles and metal hydroxide particles.

[0101] Preferred metal oxide fine particles include ZrO2, Al2O3, SiO2, TiO2, MgO, Gd2O3, Y2O3, ZnO, La2O3, etc. Among these, ZrO2, SiO2, Al2O3, and TiO2 are particularly preferred.

[0102] Preferred metal hydroxide fine particles include Al(OH)3, etc.

[0103] A method for manufacturing the phosphor powder of the present embodiment will be described.

[0104] As an example of the method for manufacturing the phosphor powder, it is obtained by dry mixing α-sialon phosphor particles and inorganic fine particles. In the dry mixing, the α-sialon phosphor particles and the inorganic fine particles can be mixed without using a solvent.

[0105] As an apparatus for industrially performing dry mixing, a known mixing apparatus can be used.

[0106] On a laboratory scale, dry mixing can be performed by putting the α-sialon phosphor particles and the inorganic fine particles into a zip-lock plastic bag and shaking vigorously.

[0107] In the case where the phosphor powder composed of α-sialon phosphor particles (inorganic fine particles are attached) manufactured by dry mixing contains coarse particles, it is preferable to appropriately perform operations such as sieving.

[0108] As another example of the method for manufacturing the phosphor powder, α-sialon phosphor particles and inorganic fine particles can be wet-mixed in a solvent such as a solvent or water, and then the solvent is removed and dried. For example, the inorganic fine particles are dispersed in a solvent by a wet jet mill or the like, and then the phosphor particles are mixed, and the solvent is removed and dried, so that the inorganic fine particles can be more uniformly attached to the surface of the phosphor.

[0109] <Light-emitting device>

[0110] Regarding an example of the light-emitting device of the present embodiment, it includes a light-emitting light source and a wavelength conversion member including a phosphor powder.

[0111] The wavelength conversion member may include a phosphor powder and a sealing material for sealing the phosphor powder.

[0112] In the wavelength conversion member, a plurality of phosphor particles in the phosphor powder are dispersed in the sealing material.

[0113] As the sealing material, known materials such as resins or glasses can be used. As the resin used in the sealing material, for example, transparent resins such as silicone resins, epoxy resins, and urethane resins can be cited.

[0114] As a method for manufacturing the wavelength conversion member, for example, a method can be cited in which a phosphor powder is added to a liquid resin or glass and uniformly mixed, and then cured by heat treatment.

[0115] Figure 1 It is a cross-sectional view schematically showing an example of the structure of the light-emitting device of the present embodiment. As Figure 1 shown, the light-emitting device 100 includes a light-emitting element 120, a heat sink 130, a housing 140, a first lead frame 150, a second lead frame 160, bonding wires 170, a bonding wire 172, and a wavelength conversion member 40.

[0116] The light-emitting element 120 is mounted on a predetermined area on the upper surface of the heat sink 130. By mounting the light-emitting element 120 on the heat sink 130, the heat dissipation performance of the light-emitting element 120 can be improved. In addition, a packaging substrate can also be used instead of the heat sink 130.

[0117] The light-emitting element 120 is a semiconductor element that emits excitation light. As the light-emitting element 120, for example, an LED chip that generates light with a wavelength of 300 nm or more and 500 nm or less, which corresponds to near-ultraviolet to blue light, can be used. One electrode (not shown) disposed on the upper surface side of the light-emitting element 120 is connected to the surface of the first lead frame 150 via a bonding wire 170 such as a gold wire. Further, another electrode (not shown) formed on the upper surface of the light-emitting element 120 is connected to the surface of the second lead frame 160 via a bonding wire 172 such as a gold wire.

[0118] In the housing 140, a recess having a substantially funnel shape with a pore diameter gradually expanding upward from the bottom surface is formed. The light-emitting element 120 is disposed on the bottom surface of the recess. The wall surface of the recess surrounding the light-emitting element 120 functions as a reflector.

[0119] The wavelength conversion member 40 is filled into the recess formed by the housing 140 with the wall surface. The wavelength conversion member 40 converts the excitation light emitted from the light-emitting element 120 into light with a longer wavelength.

[0120] As the wavelength conversion member 40, the composite body of the present embodiment can be used, and phosphor particles 10 are dispersed in a sealing material 30 such as resin. The light-emitting device 100 emits a mixed color of the light of the light-emitting element 120 and the light generated from the phosphor particles 10 that absorb and excite the light of the light-emitting element 120.

[0121] In addition, Figure 1 a surface-mount type light-emitting device is exemplified, but the light-emitting device is not limited to the surface-mount type, and may also be a bullet type, a COB (chip on board) type, or a CSP (chip scale package) type.

[0122] As described above, embodiments of the present invention have been described, but these are examples of the present invention, and various structures other than those described above can be adopted. Further, the present invention is not limited to the above embodiments, and variations, improvements, etc. within the scope capable of achieving the object of the present invention are also included in the present invention.

[0123] Examples

[0124] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited by any of the descriptions of these examples.

[0125] <Manufacture of phosphor powder>

[0126] (Comparative Example 1)

[0127] Inside the glove box, as the composition of the raw material powder, 62.8 parts by mass of silicon nitride powder (manufactured by Ube Industries, Ltd., E10 grade), 22.7 parts by mass of aluminum nitride powder (manufactured by Tokuyama Corporation, E grade), 1.1 parts by mass of europium oxide powder (manufactured by Shin-Etsu Chemical Co., Ltd., RU grade), and 13.4 parts by mass of calcium nitride powder (manufactured by Kojundo Chemical Lab. Co., Ltd.) were used. After dry-mixing the raw material powders, they were passed through a nylon sieve with a mesh size of 250 μm to obtain a raw material mixed powder. 120 g of this raw material mixed powder was filled into a covered cylindrical boron nitride container (manufactured by DENKA COMPANY LIMITED, N-1 grade) with an internal volume of 0.4 liters.

[0128] The raw material mixed powder together with the container was heated in an electric furnace with a carbon heater for 10 hours at 1850 °C under an atmospheric nitrogen environment. Calcium nitride contained in the raw material mixed powder is easily hydrolyzed in air. Therefore, after the boron nitride container filled with the raw material mixed powder was taken out of the glove box, it was quickly put into the electric furnace and immediately evacuated to prevent the reaction of calcium nitride.

[0129] The synthesized product was gently crushed in a mortar and completely passed through a sieve with a mesh size of 150 μm.

[0130] The material that passed through the sieve was immersed in a mixed acid of hydrofluoric acid and nitric acid for 1 hour for cleaning. After cleaning, filtration was carried out to separate the phosphor and the treatment liquid. The phosphor was dried in a dryer at 100 °C to 120 °C for 12 hours. After drying, it was classified using a sieve with a mesh size of 150 μm, and only the material that passed through the sieve was recovered to obtain α-sialon phosphor particles A.

[0131] In Comparative Example 1, the obtained α-sialon phosphor particles A were used as the phosphor powder.

[0132] (Comparative Example 2)

[0133] As the composition of the raw material powder, the conditions of the α-sialon phosphor particles obtained in Comparative Example 1 were changed to 10 parts by mass, the conditions of the silicon nitride powder (manufactured by Ube Industries, Ltd., E10 grade) were changed to 56.6 parts by mass, the conditions of the aluminum nitride powder (manufactured by Tokuyama Corporation, E grade) were changed to 20.4 parts by mass, the conditions of the europium oxide powder (manufactured by Shin-Etsu Chemical Co., Ltd., RU grade) were changed to 1.0 part by mass, the conditions of the calcium nitride powder (manufactured by Kojundo Chemical Lab. Co., Ltd.) were changed to 12.0 parts by mass, and the heat treatment time condition was changed to 20 hours. Except for this, α-sialon phosphor particles B were obtained in the same manner as in Comparative Example 1.

[0134] In Comparative Example 2, the obtained α-sialon phosphor particles B were used as the phosphor powder.

[0135] (Examples 1 to 3)

[0136] Phosphor particles and inorganic fine particles were put into a polyethylene zippered bag (product name “UNIPACK (registered trademark)”, manufactured by SEISANNIPPONSHA LTD.). Then, the bag was shaken vigorously for 1 minute. The mixture taken out of the bag was completely passed through a sieve with a mesh size of 250 μm, thereby obtaining the phosphor powder.

[0137] The types of phosphor particles, the types of inorganic fine particles, and the addition amounts are as described in Table 1 below.

[0138] In Table 1, the information of the inorganic fine particles is as follows.

[0139] ·Al2O3 (γ, δ): Particles of dry alumina (AEROXIDE (registered trademark) Alu C, manufactured by NIPPON AEROSIL CO., LTD., Al2O3 content: 99.8% by mass, surface untreated product, BET specific surface area: 100 m 2 / g, primary particle size: about 13 nm, average particle size 1 μm or less)

[0140] As a result of investigating the crystal phase of the α-sialon phosphor particles A and B manufactured above by powder X-ray diffraction (X-ray Diffraction) using CuKα rays, it was confirmed that the existing crystal phase was Ca-α-sialon containing Eu element (α-sialon phosphor containing Ca).

[0141] The phosphor powders produced in Examples 1 to 3 were photographed with an electron microscope. It was confirmed from the photographed images that inorganic fine particles were attached to the surfaces of the α-sialon phosphor particles.

[0142] [Table 1]

[0143]

[0144] Regarding the phosphor powders obtained above, the following items were measured / evaluated.

[0145] <Measurement of tapped bulk density>

[0146] An auxiliary cylinder was attached to a dry cylindrical measuring container of a specified volume, and the phosphor powder produced above was introduced as a measurement sample into the interior of the measuring container through the auxiliary cylinder. The measuring container with the auxiliary cylinder was tapped 50 times in the vertical direction at 50 - 60 times per minute under the condition of a stroke of 2 cm. After tapping, the auxiliary cylinder was removed, and the excess measurement sample was scraped off from the upper surface of the measuring container, and the total mass was measured. The mass of the empty cylindrical container measured in advance was subtracted from the total mass, thereby measuring the mass of the measurement sample filled in the measuring container. The measured value was obtained by dividing the mass (g) of the filled measurement sample by the internal volume (cm 3 ) of the measuring container. The average value of the three measured values was set as the above-mentioned tapped bulk density (g / cm 3 ).

[0147] In addition, in each of Examples 1 to 3, the tapped bulk density ratios represented by the tapped bulk density of the phosphor powder (α-sialon phosphor particles A) / the tapped bulk density of the phosphor powder (α-sialon phosphor particles A + inorganic fine particles) were 1.09, 1.04, and 0.77.

[0148] <Measurement of angle of repose based on the injection-limited bottom method>

[0149] Figure 2 It is a diagram for explaining the measurement of the angle of repose based on the injection-limited bottom method.

[0150] As Figure 2 shown, a frustum of a cone 1 having a bottom surface with a diameter of φ33 mm and a hose 2 having a front port with an inner diameter of 4φ mm were prepared, and the hose 2 was fixed such that the front port was at a height of 40 mm from the bottom surface.

[0151] Regarding the frustum 1, a cylindrical glass bottle made of silicate glass (manufactured by AS ONE Corporation, LABORAN spiral tube bottle, 9-852-09 No.7, 50 cc) was placed upside down on the workbench, and the bottom surface of the cylindrical bottle was used as the stage for placing the measurement sample 3.

[0152] Regarding the hose 2, a tube was used which was obtained by cutting off the tip of a polypropylene pipette tip (manufactured by Gilson, Diamond Tip D10mL EASY·PACK 1 - 10mL, product number F161210) and adjusting it so that the hole at the tip became Φ4 mm.

[0153] Next, the phosphor powder was supplied as the measurement sample 3 into the hose 2, and it was continuously allowed to freely fall from the front end port of the hose 2 towards the center of the bottom surface of the frustum 1 until the measurement sample 3 reached a state where it steadily overflowed from the bottom surface (a state where the measurement sample 3 could not be held on the bottom surface).

[0154] Then, a photograph was taken from the side of the deposit 5 of the measurement sample 3, and based on the taken photograph, the elevation angle (θ) formed between the side surface of the conical deposit 5 of the measurement sample 3 formed on the bottom surface of the frustum 1 and the bottom surface of the frustum 1 was obtained, and this elevation angle was set as the angle of repose (°) based on the injection - limited bottom surface method described above.

[0155] <Measurement of the angle of repose based on the bottom - surface non - limited injection method>

[0156] 20 g of the measurement sample was allowed to fall onto the substrate from a height of 2 - 4 cm above the upper edge of a commercially available glass funnel with a nozzle inner diameter of 10 mm at a speed of 20 - 60 g per minute through this funnel, and the low angle was calculated based on the diameter and height of the generated conical deposit. This measurement was performed 3 times, and the average value of the low angles was set as the angle of repose.

[0157] Regarding the measurement sample, the phosphor powder (α - type sialon phosphor particles A) of Comparative Example 1 was used.

[0158] <Measurement of particle size>

[0159] Regarding the particle size distribution, it was measured using a Microtrac MT3300EXII (manufactured by Microtrac BEL Corp.) by the laser diffraction scattering method in accordance with JIS R1629:1997. 0.5 g of the phosphor powder was put into 100 cc of ion-exchanged water, and it was dispersed for 3 minutes using an ultrasonic homogenizer US-150E (manufactured by NIHONSEIKIKAISHA LTD., probe size φ20 mm, Amplitude 100%, oscillation frequency 19.5 kHz, amplitude approximately 31 μm), and then the particle size distribution was measured using the MT3300EXII. In the obtained volume frequency particle size distribution, the particle size (D5) at which the cumulative value becomes 5% from the small particle size side, the particle size (D 50 ) at which the cumulative value becomes 50%, and the particle size (D 97 ) at which the cumulative value becomes 97% were respectively determined, and (D 97 -D5) / D 50 was calculated.

[0160] <Evaluation of metering stability based on the feeding test>

[0161] Figure 3 This is a diagram for explaining the feeding test.

[0162] As Figure 3 shown in (a) therein, a linear feeder 6 (manufactured by SANKI Co., rubber foot type, PEF-L30AG) was set on a horizontal table, a controller 7 (manufactured by SANKI Co., piezoelectric controller, model P111) was connected to the linear feeder 6, and a chute 8 (maximum length 300 mm, maximum width 20 mm) was horizontally installed on the linear feeder 6. As Figure 3 shown in the cross-sectional view of (b) therein, a triangular groove 9 with a maximum height of 5 mm was formed in the chute 8.

[0163] As Figure 3 shown in the cross-sectional view of (c) therein, the phosphor powder manufactured above was filled as the measurement sample 3 into the groove 9 of the chute 8, and the remaining part was scraped off from the upper surface of the groove 9.

[0164] Next, the frequency was changed using the controller 7, and the vibration was adjusted so that the feeding amount of the measurement sample 3 became about 0.02 g to 0.30 g / 5 seconds, and the vibration conditions were determined.

[0165] Five feeding tests were carried out under the fixed vibration conditions, and the feeding amount (g) within 5 seconds was measured.

[0166] Find the average value and standard deviation of the five measurement values, and calculate the coefficient of variation of the feed rate according to "(standard deviation) / average value". The smaller the coefficient of variation, the smaller the deviation of the feed rate in each feed test, indicating higher metering stability.

[0167] It can be seen as follows: By using the phosphor powders of Examples 1 to 3, compared with Comparative Example 1, the filling accuracy of container filling can be improved, and the deviation of the feed rate in the actual process can be suppressed.

[0168] The phosphor powders of Examples 1 to 3 showed the following results: Compared with Comparative Example 1, the angle of repose based on the injection-limited bottom method was smaller; compared with Comparative Example 2, the angle of repose and tapped bulk density based on the injection-limited bottom method were smaller; compared with Comparative Examples 1 and 2, the metering stability was more excellent.

[0169] This application claims the priority based on Japanese Patent Application No. 2022-178046 filed on November 7, 2022, and incorporates all the contents of this disclosure therein.

[0170] Symbol Explanation

[0171] 1 Truncated cylinder

[0172] 2 Hose

[0173] 3 Test sample

[0174] 5 Deposit

[0175] 6 Linear feeder

[0176] 7 Controller

[0177] 8 Chute

[0178] 9 Groove

[0179] 10 Phosphor particles

[0180] 30 Sealing material

[0181] 40 Composite

[0182] 100 Light-emitting device

[0183] 120 Light-emitting element

[0184] 130 Heat sink

[0185] 140 Housing

[0186] 150 First lead frame

[0187] 160 Second lead frame

[0188] 170 Bonding wire

[0189] 172 bonding wire

Claims

1. A phosphor powder comprising α-sialon phosphor particles, wherein the angle of repose of the phosphor powder measured by the following step A based on the injection-limited bottom surface method is 55° or less, The tapped bulk density of the phosphor powder measured according to Step B below is 0.95 g / cm 3 Hereinafter, Step A: Prepare a frustum of a cone having a bottom surface with a diameter of φ33 mm and a hose having a front end port with an inner diameter of 4φ mm, and fix the hose such that the front end port is at a height of 40 mm from the bottom surface; Supply the phosphor powder as a measurement sample into the hose, and let it continuously and freely fall from the front end port toward the center of the bottom surface until the measurement sample reaches a state where it stably overflows from the bottom surface; Then, find the elevation angle formed between the side surface of the conical measurement sample deposit formed on the bottom surface and the bottom surface, and set this elevation angle as the angle of repose (°) based on the injection-limited bottom surface method; Step B: Install an auxiliary cylinder on a cylindrical measuring container of a specified capacity in a dry state, and introduce the phosphor powder as a measurement sample into the interior of the measuring container through the auxiliary cylinder; for the measuring container with the auxiliary cylinder, tap it 50 times in the vertical direction at 50 - 60 times per minute under the condition of a stroke of 2 cm; after tapping, remove the auxiliary cylinder, scrape off the excess measurement sample from the upper surface of the measuring container, and measure the total mass; subtract the mass of the empty cylindrical container measured in advance from the total mass, thereby measuring the mass of the measurement sample filled into the measuring container; divide the mass (g) of the filled measurement sample by the internal volume (cm 3 ) of the measuring container to obtain the measured value; set the average value of the three measured values as the above tapped bulk density (g / cm 3 ).

2. The phosphor powder according to claim 1, wherein the angle of repose is 20° or more.

3. The phosphor powder according to claim 1 or 2, wherein The vibration-compacted bulk density is 0.30 g / cm 3 or more.

4. The phosphor powder according to claim 1 or 2, which contains inorganic fine particles.

5. The phosphor powder according to claim 4, wherein the content of the inorganic fine particles is 0.005 mass% or more and 10 mass% or less in 100 mass% of the phosphor powder.

6. The phosphor powder according to claim 4, wherein the average particle diameter of the inorganic fine particles is 10 μm or less.

7. The phosphor powder according to claim 4, wherein the inorganic fine particles contain at least one selected from the group consisting of metal oxide particles and metal hydroxide particles.

8. The phosphor powder according to claim 4, wherein the primary particles of the inorganic fine particles and / or the aggregates of the primary particles adhere to a part of the surface of the α-sialon phosphor particles.

9. The phosphor powder according to claim 1 or 2, wherein In the volume frequency particle size distribution determined by the wet-based laser diffraction scattering method, the particle size at which the cumulative value becomes 5% starting from the small particle size side is defined as D5, the particle size at which the cumulative value becomes 50% is defined as D 50 , and the particle size at which the cumulative value becomes 97% is defined as D 97 when (D 97 - D5) / D 50 is 2.0 or more and 5.0 or less.

10. A light-emitting device comprising: a light-emitting light source; and a wavelength conversion member, wherein the wavelength conversion member contains the phosphor powder according to claim 1 or 2.

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