JP7445155B2 - Fluoride phosphor and its manufacturing method, wavelength conversion member, and light emitting device - Google Patents

Description

The present disclosure relates to a fluoride phosphor, a method for manufacturing the same, a wavelength conversion member, and a light emitting device.

Light-emitting devices that combine light-emitting elements and phosphors are used in a wide range of fields such as lighting, vehicle lighting, displays, and backlights for liquid crystals. For example, phosphors used in light-emitting devices used as backlights for liquid crystal display devices are required to have a narrow half-value width of the emission peak and high color purity. Examples of such a phosphor include a red-emitting fluoride phosphor having a specific composition disclosed in Patent Document 1.

JP2010-209311A

In light-emitting devices that are required to be smaller and thinner, there is a need to reduce the amount of phosphor used. One aspect of the present disclosure aims to provide a fluoride phosphor that can reduce the amount of phosphor required to achieve predetermined light emission characteristics in a light-emitting device.

The first aspect is a fluoride phosphor containing fluoride particles having an average particle size of 0.1 μm or more and 7 μm or less, a maximum particle size of 1 μm or more and 18 μm or less, and a ratio of the maximum particle size to the average particle size of more than 1. It is. The fluoride particles contain an element M containing at least one selected from the group consisting of a group 4 element, a group 13 element, and a group 14 element, an alkali metal, Mn, and F, and the alkali metal When the number of moles of is 2, the number of moles of Mn is more than 0 and less than 0.2, the number of moles of element M is more than 0.8 and less than 1, and the number of moles of F is less than 5. more than 7 and less than 7.

A second aspect is a wavelength conversion member including a wavelength conversion layer containing the fluoride phosphor of the first aspect and a resin.

A third aspect is a light emitting device including the wavelength conversion member of the second aspect and a light emitting element.

A fourth aspect includes preparing first fluoride particles having an average particle size of 5 μm or more and 30 μm or less, and pulverizing the first fluoride particles so that the average particle size is 0.1 μm or more and 7 μm or less. , obtaining second fluoride particles having a maximum particle size of 1 μm or more and 18 μm or less, and a ratio of the maximum particle size to the average particle size of more than 1.

According to one aspect of the present disclosure, it is possible to provide a fluoride phosphor that can reduce the amount of phosphor required to achieve predetermined light emission characteristics in a light-emitting device.

It is a scanning electron microscope (SEM) image illustrating a method for measuring the maximum length of fluoride particles. 1 is an enlarged SEM image illustrating how to measure the maximum length of fluoride particles. 1 is an example of a SEM image of a fluoride phosphor according to Comparative Example 1. 1 is an example of a SEM image of a fluoride phosphor according to Example 1. 3 is an example of a SEM image of a fluoride phosphor according to Example 2.

In this specification, the term "process" is used not only to refer to an independent process, but also to include a process in which the intended purpose of the process is achieved even if the process cannot be clearly distinguished from other processes. . Further, the content of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Further, the upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined. In this specification, the relationship between color names and chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, etc. are in accordance with JIS Z8110. The half-width of a phosphor means the wavelength width (full width at half maximum; FWHM) of the emission spectrum where the emission intensity is 50% of the maximum emission intensity in the emission spectrum of the phosphor. Embodiments of the present invention will be described in detail below. However, the embodiments shown below illustrate a fluoride phosphor, a wavelength conversion member, and a light emitting device for embodying the technical idea of the present invention. The present invention is not limited to a body, a wavelength conversion member, and a light emitting device.

Fluoride phosphor The fluoride phosphor has an average particle size of 0.1 μm or more and 7 μm or less, a maximum particle size of 1 μm or more and 18 μm or less, and the ratio of the maximum particle size to the average particle size (maximum particle size/average particle size ) contains fluoride particles larger than 1. The fluoride particles contain an element M containing at least one selected from the group consisting of a group 4 element, a group 13 element, and a group 14 element, an alkali metal, Mn, and F, and the alkali metal When the number of moles of is 2, the number of moles of Mn is more than 0 and less than 0.2, the number of moles of element M is more than 0.8 and less than 1, and the number of moles of F is less than 5. more than 7 and less than 7.

Constructing a light emitting device using a fluoride phosphor obtained by controlling the average particle size and maximum particle size of fluoride particles having a composition in which the Mn concentration serving as an activator is appropriately controlled. Accordingly, the amount of fluoride phosphor used to achieve a predetermined chromaticity coordinate (for example, CIE chromaticity coordinate value x of 0.16 or more and 0.26 or less) can be reduced. For example, this can be considered as follows. The higher the Mn concentration as an activator, the higher the wavelength conversion efficiency, and therefore the amount of fluoride phosphor used can be reduced. On the other hand, if the Mn concentration is too high, concentration quenching occurs, leading to deterioration of the characteristics of the light emitting device. Therefore, in the fluoride phosphor, it is necessary to appropriately control the Mn concentration. Furthermore, as the average particle diameter of the fluoride particles is made smaller, the scattering of excitation light on the surface of the fluoride particles increases, so the amount of fluoride phosphor used to obtain the same emission characteristics can be reduced. On the other hand, if the average particle size becomes too small, the fluorescence efficiency will decrease due to crystal defects present on the surface of the fluoride particles, so it is necessary to control the average particle size and maximum particle size within appropriate ranges. Further, by controlling the maximum particle size within an appropriate range, it is possible to suppress variations in chromaticity of light emitted from the light emitting device.

The fluoride particles constituting the fluoride phosphor need only contain at least a fluorescent substance activated by Mn, and may be composed only of a fluorescent substance activated by Mn. The fluorescent substance activated by Mn may have, for example, a crystal structure in which the main crystal phase is the same as K ₂ SiF ₆ crystal, and this crystal structure can be confirmed by powder X-ray diffraction. Since the main crystal phase of the fluoride particles has the same crystal structure as the K ₂ SiF ₆ crystal, a desired emission peak wavelength can be obtained and good brightness can be achieved. The fluoride particles may be a single phase in which the mixing of crystal phases other than the main crystal phase is suppressed, and may contain crystal phases other than the main crystal phase as long as the properties of the fluoride phosphor are not significantly affected. Good too.

The average particle size of the fluoride particles constituting the fluoride phosphor may be 0.1 μm or more and 7 μm or less, preferably 0.2 μm or more, or 0.5 μm or more. Further, the average particle size may preferably be 5 μm or less, or 3 μm or less. The average particle size of fluoride particles is determined by the F.I. S. S. S. No. (Fisher Sub Sieve Sizer's No.). The average particle size by the FSSS method is measured using, for example, Fisher Sub-Sieve Sizer Model 95 manufactured by Fisher Scientific. The inventors have confirmed that the average particle size measured by this method has a good correlation with the average particle size determined from a SEM image. The average particle diameter determined from the SEM image is calculated as follows. After obtaining multiple SEM images with approximately 100 fluoride particles observed in one image at an accelerating voltage of 5 kV and a magnification of 250 to 5000 times, the minimum and maximum lengths of each particle were measured. The particle size of the particle is determined by averaging both values. The average particle diameter obtained from the SEM image is calculated by obtaining the arithmetic mean of 1000 particles having the obtained particle diameter.

If the average particle size of the fluoride particles is 7 μm or less, it is possible to reduce the amount of fluoride phosphor required to achieve desired light emission characteristics in a light emitting device equipped with a wavelength conversion member containing a fluoride phosphor. can. Furthermore, variations in the amount of distribution of the fluoride phosphor in the wavelength conversion member can be suppressed, and fluctuations in excitation efficiency due to variations in the amount of distribution can be suppressed, thereby suppressing variations in chromaticity of the emitted light color. When the average particle size is 0.1 μm or more, the dispersibility of the fluoride phosphor in the resin constituting the wavelength conversion member is improved, and the fluoride phosphor can be distributed more uniformly. Thereby, a highly uniform wavelength conversion member can be easily constructed, and the luminous flux of the light emitting device tends to be further improved.

The maximum particle size of the fluoride particles may be 1 μm or more and 18 μm or less, preferably 15 μm or less, 10 μm or less, or 6 μm or less. The maximum particle size of fluoride particles is measured in a scanning electron microscope (SEM) image as follows. At an accelerating voltage of 5 kV and a magnification of 250 times, an SEM image in which approximately 500 or more fluoride phosphor particles are observed is obtained. Further enlarged SEM images of each of the plurality of particles estimated to have the maximum particle size are obtained. The magnification at that time will be approximately 5000 times. The maximum length of each of these plural particles is measured from the scale of the SEM image that has been calibrated in advance. The maximum lengths of the measured particles are compared, and the maximum length of the particle that gives the maximum value is taken as the maximum particle size of the fluoride particle. In addition, the maximum length of a particle is a line segment that connects any two points on the outer circumference of a particle that is observed to exist independently from other particles, and is a line segment that passes through the inside of the particle. , let the length of the longest line segment be the maximum length of the particle. Here, "a particle observed to exist independently from other particles" means a particle that is determined not to be adhered to other particles. Furthermore, if the particle is a secondary particle formed by agglomeration of a plurality of primary particles, the maximum length of the secondary particle is measured.

How to determine the maximum length of a particle will be explained with reference to the drawings. Figure 1 is an example of a 250x SEM image of fluoride particles. From the field of view of the SEM image in FIG. 1, particles indicated by white circles are selected as particles estimated to have the maximum length. A 5000x SEM image is shown in FIG. 2 as a further enlarged image of the selected particles. As shown in FIG. 2, the selected particles are secondary particles consisting of a plurality of primary particles. As shown in FIG. 2, the maximum length of the fluoride particle is measured as the maximum length line segment connecting two points on the outer periphery of the secondary particle.

When the maximum particle size of the fluoride particles is 18 μm or less, the dispersibility of the fluoride phosphor in the resin constituting the sheet-like wavelength conversion member tends to improve. In addition, the mixing state of the wavelength conversion member with other fluorescent materials contained therein becomes more uniform, which tends to suppress chromaticity fluctuations in the sheet-shaped wavelength conversion member and occurrence of color unevenness on the irradiation surface of the light emitting device. .

The maximum particle size of the fluoride particles may be larger than the average particle size, that is, the lower limit of the ratio of the maximum particle size to the average particle size may be larger than 1, preferably 2 or more, or 5 or more. good. The upper limit of the ratio of maximum particle size to average particle size may be 10 or less, preferably 6 or less.

The particle size distribution of the fluoride phosphor may exhibit a single peak particle size distribution, for example, from the viewpoint of improving brightness. The particle size distribution of the fluoride phosphor may preferably exhibit a single peak particle size distribution with a narrow distribution width. Specifically, in the volume-based particle size distribution, if D10 is the particle size corresponding to 10% cumulative volume from the small diameter side and D90 is the particle size corresponding to 90% cumulative volume, then the ratio of D90 to D10 (D90 /D10) may be 10 or less.

The fluoride particles include an element M containing at least one selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements, an alkali metal, Mn, and F. It's okay to stay. In the composition of the fluoride particles, when the number of moles of the alkali metal is 2, the number of moles of Mn may be more than 0 and less than 0.2, preferably 0.01 or more and 0.12 or less. good. In addition, the composition of the fluoride particles is such that when the number of moles of the alkali metal is 2, the number of moles of element M may be more than 0.8 and less than 1, preferably 0.88 or more and 0.99 or less. It's good. In the composition of the fluoride particles, when the number of moles of the alkali metal is 2, the number of moles of F may be more than 5 and less than 7, preferably 5.9 or more and 6.1 or less. The composition of fluoride particles can be determined, for example, by inductively coupled plasma (ICP) optical emission spectroscopy. Further, for details of the composition of the fluoride particles, reference can be made to, for example, Japanese Patent Application No. 2021-091754.

Element M in the composition of the fluoride particles includes at least one selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. Examples of the Group 4 element include titanium (Ti), zirconium (Zr), hafnium (Hf), etc., and at least one selected from the group consisting of these may be included. Group 13 elements include boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), etc., and contain at least one element selected from the group consisting of these. It's okay to stay. Examples of Group 14 elements include carbon (C), silicon (Si), germanium (Ge), tin (Sn), etc., and at least one selected from the group consisting of these may be included. Element M may contain at least one kind of Group 14 element, and preferably may contain at least one of Si and Ge. Furthermore, the element M may include at least one group 13 element and at least one group 14 element, and preferably may include at least one of Al, Si, and Ge.

The alkali metal in the composition of the fluoride particles may include at least one selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Further, the alkali metal includes at least potassium (K), and may also include at least one selected from the group consisting of lithium (Li), sodium (Na), rubidium (Rb), and cesium (Cs). The ratio of the number of moles of K to the total number of moles of alkali metals in the composition may be, for example, 0.90 or more, and preferably 0.97 or more. The upper limit of the ratio of the number of moles of K may be, for example, 1 or 0.995 or less. In the composition of the fluoride particles, a part of the alkali metal may be replaced with ammonium ions (NH ₄ ⁺ ). When part of the alkali metal is replaced with ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of alkali metals in the composition may be, for example, 0.10 or less, preferably 0.03 or less. . The lower limit of the molar number ratio of ammonium ions may be, for example, more than 0, and preferably 0.005 or more.

The first composition, which is one aspect of the composition of the fluoride particles, may include at least one element M selected from the group consisting of Group 4 elements and Group 14 elements, preferably from Group 14 elements. It may contain at least one selected from the group consisting of: more preferably at least one of Si and Ge, still more preferably at least Si. Further, in the first composition of the fluoride particles, the total number of moles of Si, Ge, and Mn may be 0.9 or more and 1.1 or less, preferably 0.97 or more, relative to 2 moles of the alkali metal. It may be 1.03 or less.

The first composition of the fluoride particles may be a composition represented by the following formula (1).
A ¹ _c [M ¹ _1-b Mn _b F _d ] (1)

In formula (1), A ¹ may contain at least one selected from the group consisting of Li, Na, K, Rb, and Cs. ^M1 contains at least one of Si and Ge, and may further contain at least one element selected from the group consisting of Group 4 elements and Group 14 elements. Mn may be a tetravalent manganese ion. b satisfies 0<b<0.2, c is the absolute value of the charge of the [M ¹ _1-b Mn _b F _d ] ion, and d satisfies 5<d<7.

A ¹ in formula (1) includes at least K, and may further include at least one selected from the group consisting of Li, Na, Rb, and Cs. Further, a portion of A ¹ may be substituted with ammonium ions (NH ₄ ⁺ ). When part of A ¹ is substituted with ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of A ¹ in the composition may be, for example, 0.10 or less, preferably 0.05 or less, or It is 0.03 or less. The lower limit of the molar number ratio of ammonium ions may be, for example, more than 0, and preferably 0.005 or more.

b in formula (1) is preferably 0.005 or more and 0.15 or less, or 0.015 or more and 0.1 or less. c may be, for example, 1.8 or more and 2.2 or less, preferably 1.95 or more and 2.05 or less. d may preferably be 5.5 or more and 6.5 or less, and 5.9 or more and 6.1 or less.

The second composition, which is one aspect of the composition of the fluoride particles, contains at least one element M selected from the group consisting of Group 4 elements and Group 14 elements, and at least one Group 13 element. It may contain at least one kind selected from the group consisting of Group 14 elements and at least one kind of Group 13 elements, and more preferably at least Si and Al. In addition, in the second composition of the fluoride particles, the total number of moles of Si, Al, and Mn may be 0.9 or more and 1.1 or less, preferably 0.97 to 2 moles of the alkali metal. It may be greater than or equal to 1.03. Further, in the second composition of the fluoride particles, the number of moles of Al may be more than 0 and less than 0.1, preferably more than 0.003 and less than 0.015, with respect to 2 moles of the alkali metal. It's fine.

The second composition of the fluoride particles may be a composition represented by the following formula (2).
A ² _f [M ² _1-e Mn _e F _g ] (2)

In formula (2), A ² contains at least K, and may further contain at least one selected from the group consisting of Li, Na, Rb, and Cs. ^M2 contains at least Si and Al, and may further contain at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. Mn may be a tetravalent manganese ion. e satisfies 0<e<0.2, f is the absolute value of the charge of the [M ² _1-e Mn _e F _g ] ion, and g satisfies 5<g<7.

A ² in formula (2) may be partially substituted with ammonium ions (NH ₄ ⁺ ). When a part of A ² is replaced with ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of A ² in the composition may be, for example, 0.10 or less, and preferably 0.03 or less. . The lower limit of the molar number ratio of ammonium ions may be, for example, more than 0, and preferably 0.005 or more.

e in formula (2) is preferably 0.005 or more and 0.15 or less, or 0.015 or more and 0.1 or less. f may be, for example, 1.8 or more and 2.2 or less, preferably 1.95 or more and 2.05 or less. g may preferably be 5.5 or more and 6.5 or less, and 5.9 or more and 6.1 or less.

The fluoride particles constituting the fluoride phosphor may have an inorganic substance other than the fluoride particles attached to at least a portion of the surface thereof. Since agglomeration of the fluoride particles is suppressed by attaching an inorganic substance to the surface of the fluoride particles, for example, the dispersibility in the resin tends to be improved. Additionally, the moisture resistance of fluoride phosphors tends to improve. Examples of inorganic substances other than fluoride particles include oxides, metal salts, fluorides, nitrides, etc., and may contain at least one selected from the group consisting of these, preferably oxidized It may contain at least one selected from the group consisting of metal salts and metal salts. The inorganic substances attached to the fluoride particles may be used alone or in combination of two or more. When using a combination of two or more types of inorganic substances, a mixture of the inorganic substances may be attached to the fluoride particles, or each inorganic substance may be attached sequentially to form a multilayer structure.

The oxide may contain at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn. That is, the oxide includes silicon oxide (e.g., SiOx, where x may be 1 or more and 2 or less, preferably 1.5 or more and 2 or less, or about 2), aluminum oxide (e.g., Al ₂ O ₃ ), oxide Contains at least one selected from the group consisting of titanium (e.g., TiO ₂ ), zirconium oxide (e.g., ZrO ₂ ), tin oxide (e.g., SnO, SnO _{2 ,} etc.), and zinc oxide (e.g., ZnO). Often, it may contain at least silicon oxide. The oxide may consist of only one type, or may contain a combination of two or more types.

The content of the oxide in the fluoride phosphor may be 0.02% by mass or more and 30% by mass or less, preferably 1% by mass or more and 15% by mass or less based on the fluoride phosphor. The oxide content in the fluoride phosphor can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopy.

The metal salt may include, for example, rare earth phosphates, alkaline earth metal phosphates, etc., and may include at least one selected from the group consisting of these. The rare earth phosphate may contain at least one rare earth element selected from the group consisting of lanthanum (La), cerium (Ce), dysprosium (Dy), and gadolinium (Gd), and preferably contains at least lanthanum. It's okay to be there.

The content of the metal salt in the fluoride phosphor may be, for example, 0.1% by mass or more and 20% by mass or less, preferably 0.2% by mass or more and 10% by mass or less, as the content of the metal element. good.

Examples of fluorides other than fluoride particles include fluorides containing Group 2 elements such as magnesium fluoride and calcium fluoride, and fluorosilicate salts such as alkali metal hexafluorosilicate salts. .

The content of fluorides other than fluoride particles in the fluoride phosphor may be, for example, 0.1% by mass or more and 15% by mass or less, preferably 0.3% by mass or more and 10% by mass or less.

The inorganic substance attached to the surface of the fluoride particles may be attached as inorganic substance particles and cover the surface of the fluoride particles. Further, the inorganic substance may cover the surface of the fluoride particles in the form of a film, or may be arranged as an inorganic substance layer on the surface of the fluoride particles.

The fluoride phosphor is a phosphor activated by tetravalent manganese ions, and emits red light by absorbing light in the short wavelength range of visible light. The excitation light preferably includes light in a wavelength region where the excitation intensity of the fluoride phosphor is high, and may particularly be light in the blue region, and the emission peak wavelength of the excitation light is, for example, in a wavelength range of 380 nm or more and 485 nm or less. It may be within. The emission peak wavelength in the emission spectrum of the fluoride phosphor may be within a wavelength range of 610 nm or more and 650 nm or less, for example. The half width in the emission spectrum of the fluoride phosphor may be, for example, 10 nm or less.

Method for manufacturing fluoride phosphor The fluoride particles constituting the fluoride phosphor can be manufactured, for example, as follows. When the fluoride particles have the first composition, for example, a first complex ion containing tetravalent manganese, at least one selected from the group consisting of Group 4 elements and Group 14 elements, and a second complex ion containing fluorine ions. It can be produced by a production method including a step of mixing a solution a containing at least a complex ion and hydrogen fluoride, and a solution b containing at least an alkali metal containing at least potassium and hydrogen fluoride.

Further, for example, a first solution containing at least a first complex ion containing tetravalent manganese and hydrogen fluoride, a second solution containing at least an alkali metal containing at least potassium and hydrogen fluoride, and a group 4 element and a second solution containing at least hydrogen fluoride may be used. It can also be produced by a production method that includes a step of mixing at least one selected from the group consisting of Group 14 elements and a third solution containing at least a second complex ion containing fluorine ions. For the method for producing fluoride particles having the first composition, reference can be made to, for example, JP-A No. 2015-143318, JP-A No. 2015-188075, and the like.

When the fluoride particles have the second composition, they can be produced, for example, by the production method described in JP-A-2010-254933. Alternatively, as a method for producing fluoride particles having the second composition, for example, the description in Japanese Patent Application No. 2020-212532 can be referred to. That is, preparing fluoride particles having a first composition, preparing a fluoride containing Al, an alkali metal, and F, and preparing a mixture containing the fluoride and fluoride particles having the first composition. It can be manufactured by a manufacturing method including heat treatment at a temperature of 600° C. or higher and 780° C. or lower in an active gas atmosphere. Here, the composition of the fluoride containing Al, an alkali metal, and F is such that the ratio of the total number of moles of alkali metal is 1 to 3, and the ratio of the number of moles of F is 4 to 1 mole of Al. It may be greater than or equal to 6 or less. Alternatively, the ratio of the total number of moles of alkali metal to 1 mole of Al may be 2 or more and 3 or less, and the ratio of the mole of F may be 5 or more and 6 or less.

In the method for producing fluoride phosphors, by controlling conditions such as the concentration and dropping speed of each fluorine-containing reaction solution in which the constituent elements of fluoride particles are dissolved, it is possible to obtain a desired average particle size and maximum particle size. Fluoride particles can be precipitated.

The method for producing a fluoride phosphor may include an adjustment step of adjusting the particle size of the fluoride particles. The conditioning step may include, for example, grinding the fluoride particles to obtain a ground product. The fluoride particles to be subjected to the adjustment step may have an average particle size of, for example, 5 μm or more and 30 μm or less, preferably 7 μm or more and 25 μm or less. Further, the maximum particle size of the fluoride particles to be subjected to the adjustment step may be, for example, 10 μm or more and 100 μm or less, preferably 15 μm or more and 60 μm or less.

The method for pulverizing the fluoride particles can be appropriately selected from commonly used pulverizing methods such as a ball mill, a bead mill, and a jet mill. The fluoride particles are preferably pulverized using a wet method. By performing the wet crushing process, it is possible to narrow the particle size distribution while suppressing a decrease in the brightness of the fluoride phosphor. Wet grinding can be carried out, for example, by ball milling the fluoride particles together with grinding media in a liquid medium. Examples of the liquid medium include water, an aqueous liquid medium such as hydrogen peroxide, and an organic solvent such as ethanol. The liquid medium may include at least an aqueous liquid medium. Examples of the grinding media include alumina balls, zirconia balls, and urethane balls.

The amount of grinding media used in the grinding process may be such that the amount of fluoride particles used relative to the amount of grinding media used is, for example, 1% by mass or more and 50% by mass or less, preferably 5% by mass or more and 30% by mass. % or less.

In the pulverization process using a ball mill, it is preferable to pulverize at a low speed over a time period of, for example, 1 hour or more and 72 hours or less, while suppressing the pulverization efficiency. By pulverizing slowly with a weak shearing force for one hour or more, pulverization of the fluoride particles is suppressed, and a decrease in the brightness of the fluoride phosphor is suppressed. Productivity is improved by setting the time to 72 hours or less. The grinding time using the ball mill may preferably be 2 hours or more and 24 hours or less. Further, the temperature in the pulverization process may be, for example, 0°C or more and 80°C or less, preferably 5°C or more and 50°C or less.

The method for producing a fluoride phosphor may further include adjusting the particle size distribution of the pulverized material. By adjusting the particle size distribution of the pulverized material, fluoride particles with a narrower particle size distribution can be obtained. The particle size distribution of the pulverized product can be adjusted, for example, by washing with a liquid medium and by classification.

The method for producing a fluoride phosphor may further include a fluorine treatment step of heat-treating the fluoride particles in an atmosphere containing fluorine gas. Heat treatment in a fluorine gas atmosphere tends to further improve the brightness of fluoride phosphors. The atmosphere containing fluorine gas may contain an inert gas such as nitrogen gas in addition to fluorine gas. The concentration of fluorine gas in the atmosphere containing fluorine gas may be, for example, 1 volume % or more and 100 volume % or less, preferably 10 volume % or more and 30 volume % or less.

The temperature of the heat treatment may be, for example, 100°C or more and 700°C or less, preferably 300°C or more and 600°C or less. The heat treatment time may be, for example, 1 hour or more and 100 hours or less, preferably 2 hours or more and 48 hours or less. Here, the heat treatment time refers to the time during which a predetermined temperature is maintained after reaching the predetermined temperature.

The method for producing a fluoride phosphor may include a surface treatment step of attaching an inorganic substance to at least a portion of the surface of the fluoride particles. Through the surface treatment step, a fluoride phosphor with improved dispersibility in resin can be obtained. Further, by having an inorganic substance on the surface of the fluoride particles, the permeability of oxygen, water vapor, etc. is further reduced, and durability can be further improved. The surface treatment step can be appropriately selected from commonly used methods depending on the inorganic substance to be attached. Note that the fluoride particles used in the surface treatment step are fluoride particles whose average particle size and maximum particle size are adjusted to a desired range.

When the inorganic substance to be deposited in the surface treatment step is an oxide, for example, by bringing the fluoride particles and the metal alkoxide into contact in a liquid medium, the oxide derived from the metal alkoxide can be applied to at least a portion of the surface of the fluoride particles. It can be attached. The metal alkoxide may be, for example, a metal alkoxide containing at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn, and may be a metal alkoxide containing at least one of Si and Al. good. The aliphatic group of the alkoxide constituting the metal alkoxide may have, for example, 1 or more and 6 or less carbon atoms. For details on the method of attaching oxides to fluoride particles, reference can be made to, for example, the description in Japanese Patent Application No. 2021-091754, publicly known matters regarding the so-called sol-gel method, etc.

A specific example of the metal alkoxide is preferably at least one selected from the group consisting of tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, trimethoxyaluminum, triethoxyaluminum, and triisopropoxyaluminum.

The amount of metal alkoxide used in the surface treatment step may be, for example, 5% by mass or more and 110% by mass or less based on the total mass of the fluoride particles.

Examples of the liquid medium include water; alcohol solvents such as methanol, ethanol, and isopropyl alcohol; nitrile solvents such as acetonitrile; and hydrocarbon solvents such as hexane. The liquid medium may include at least water and an alcoholic solvent. When the liquid medium contains an alcoholic solvent, the content of the alcoholic solvent in the liquid medium may be, for example, 60% by mass or more. Further, the water content in the liquid medium may be, for example, 4% by mass or more and 40% by mass or less.

Moreover, the liquid medium may further contain a pH adjuster. As the pH adjuster, for example, alkaline substances such as ammonia, sodium hydroxide, and potassium hydroxide, and acidic substances such as hydrochloric acid, nitric acid, sulfuric acid, and acetic acid can be used. When the liquid medium contains a pH adjuster, the pH of the liquid medium may be, for example, 1 or more and 6 or less under acidic conditions. Under alkaline conditions, it may be 8 or more and 12 or less.

The mass ratio of the liquid medium to the fluoride particles may be, for example, 100% by mass or more and 1000% by mass or less. When the mass ratio of the liquid medium is within the above range, the fluoride particles tend to be more uniformly covered with the oxide.

Contact between the fluoride particles and the metal alkoxide can be carried out, for example, by adding the metal alkoxide to a suspension containing the fluoride particles. At this time, stirring or the like may be performed as necessary. Further, the contact temperature between the fluoride particles and the metal alkoxide may be, for example, 0°C or more and 70°C or less. The contact time may be, for example, 1 hour or more and 12 hours or less. Note that the contact time also includes the time required for adding the metal alkoxide.

When the inorganic substance to be attached in the surface treatment process is a metal salt, the metal salt is attached to at least part of the surface of the fluoride particles by bringing the fluoride particles, metal ions, and anions into contact in a liquid medium. Can be done. Specifically, when the metal salt is a rare earth phosphate, the fluoride particles, rare earth ions, and phosphate ions are brought into contact with each other in a liquid medium. As a result, fluoride particles having rare earth phosphates attached to their surfaces are obtained. It is believed that by attaching the rare earth phosphate to the fluoride particles in a liquid medium, the rare earth phosphate is more uniformly attached to, for example, the surface of the fluoride particles.

The liquid medium preferably contains phosphate ions, more preferably water and phosphate ions. When the liquid medium contains phosphate ions, by mixing the prepared fluoride particles with the liquid medium and further mixing with a solution containing rare earth ions, phosphate ions and rare earth ions can be dissolved in the liquid medium containing fluoride particles. can be brought into contact with. When the liquid medium contains phosphate ions, the concentration of phosphate ions in the liquid medium is, for example, 0.05% by mass or more and, for example, 5% by mass or less. When the phosphate ion concentration in the liquid medium is equal to or higher than the above lower limit, the amount of the liquid medium will not become too large, the elution of the constituent components from the fluoride particles will be suppressed, and the characteristics of the fluoride phosphor will be maintained well. Tend. Moreover, when it is below the above-mentioned upper limit, the uniformity of the deposits on the fluoride particles tends to be good.

Phosphate ions include orthophosphate ions, polyphosphate (metaphosphoric acid) ions, phosphite ions, and hypophosphite ions. Polyphosphate ions include linear polyphosphate ions such as pyrophosphate ions and tripolyphosphate ions, and cyclic polyphosphate ions such as hexametaphosphate ions.

When the liquid medium contains phosphate ions, it may be prepared by dissolving a compound serving as a phosphate ion source in the liquid medium, or it may be prepared by mixing a solution containing a phosphate ion source and the liquid medium. . Examples of phosphate ion sources include phosphoric acid; metaphosphoric acid; alkali metal phosphates such as sodium phosphate and potassium phosphate; alkali metal hydrogen phosphates such as sodium hydrogen phosphate and potassium hydrogen phosphate; Alkali metal dihydrogen phosphates such as sodium hydrogen and potassium dihydrogen phosphate; alkali metal hexametaphosphates such as sodium hexametaphosphate and potassium hexametaphosphate; alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate; phosphoric acid Examples include ammonium phosphate salts such as ammonium.

The liquid medium preferably contains a reducing agent, more preferably water and a reducing agent, and even more preferably water, phosphate ions, and a reducing agent. When the liquid medium contains a reducing agent, precipitation of manganese dioxide and the like derived from manganese contained in the fluoride particles can be effectively suppressed. The reducing agent contained in the liquid medium may be any reducing agent as long as it can reduce, for example, tetravalent manganese ions eluted from the fluoride particles into the liquid medium, and examples thereof include hydrogen peroxide, oxalic acid, hydroxyamine hydrochloride, etc. . Among these, hydrogen peroxide is preferable because it is decomposed into water and therefore does not have an adverse effect on the fluoride particles.

When the liquid medium contains a reducing agent, it may be prepared by dissolving a compound serving as the reducing agent in the liquid medium, or it may be prepared by mixing a solution containing the reducing agent and the liquid medium. The content of the reducing agent in the liquid medium is not particularly limited, but may be, for example, 0.1% by mass or more for the above reasons.

In addition to Sc and Y, rare earth elements that become rare earth ions brought into contact with phosphate ions include La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lanthanoids consisting of Lu can be mentioned.

Contact between phosphate ions and rare earth ions in a liquid medium may be carried out, for example, by dissolving a compound serving as a source of rare earth ions in a liquid medium containing phosphate ions, or by dissolving a compound serving as a source of rare earth ions in a liquid medium containing phosphate ions. This may be done by mixing with a solution containing ions. A solution containing rare earth ions can be prepared, for example, by dissolving a compound serving as a rare earth ion source in a solvent such as water. The compound serving as the rare earth ion source is, for example, a metal salt containing a rare earth element, and examples of the anions constituting the metal salt include nitrate ion, sulfate ion, acetate ion, and chloride ion.

The contact between phosphate ions and rare earth ions in a liquid medium includes, for example, mixing a liquid medium containing phosphate ions and preferably further containing a reducing agent and fluoride particles to obtain a phosphor slurry; mixing the body slurry and a solution containing rare earth ions.

The content of rare earth ions in the liquid medium in which phosphate ions and rare earth ions are brought into contact is, for example, 0.05% by mass or more and 3% by mass or less. The content of rare earth ions relative to fluoride particles in the liquid medium is, for example, 0.2% by mass or more and 30% by mass or less. When the concentration of rare earth ions is above the above lower limit, the adhesion rate of rare earth phosphates to fluoride particles tends to be further improved, and when the concentration of rare earth ions is below the above upper limit, the adhesion rate of rare earth phosphates to fluoride particles tends to improve. It tends to be easier to deposit the fluoride particles more uniformly on the surface of the fluoride particles.

The contact temperature between the phosphate ions and the rare earth ions that form the rare earth phosphate may be, for example, 10° C. or higher and 50° C. or lower. Further, the contact time may be, for example, 1 minute or more and 1 hour or less. The contact may be performed while stirring the liquid medium. For the method of attaching rare earth phosphate to the surface of fluoride particles, reference can be made to, for example, JP 2017-186524A and the like.

When the inorganic substance to be attached in the surface treatment process is fluoride, the fluoride is attached to at least a portion of the surface of the fluoride particles by bringing the fluoride particles, metal ions, and fluoride ions into contact in a liquid medium. be able to.

When the fluoride to be attached is a fluoride containing a Group 2 element such as magnesium fluoride or calcium fluoride, by bringing the fluoride particles, Group 2 metal ion, and fluoride ion into contact in a liquid medium, Fluoride particles having a fluoride containing a Group 2 element attached to their surfaces can be obtained. For details of the method for attaching fluoride containing a Group 2 element, reference can be made to, for example, Japanese Patent Application Publication No. 2015-044951.

In addition, if the fluoride to be deposited is an alkali metal fluorosilicate salt, by bringing the fluoride particles, fluorosilicate ions, and alkali metal ions into contact with each other in a liquid medium, the alkali metal fluorosilicate surface can be coated with the alkali metal fluorosilicate salt. Fluoride particles with salt attached can be obtained. For details of the method for attaching the alkali metal fluorosilicate salt, reference can be made to, for example, JP-A-2015-28148.

In the surface treatment step, two or more types of inorganic substances may be attached. For example, it may include attaching a rare earth phosphate to fluoride particles and attaching an oxide to the fluoride particles to which the rare earth phosphate is attached.

The method for producing a fluoride phosphor may further include a step of recovering the fluoride phosphor obtained after the surface treatment step by solid-liquid separation, a step of drying the solid-liquid separated fluoride phosphor, etc. good.

The method for producing a fluoride phosphor may include a coupling treatment step of treating the fluoride phosphor obtained in the surface treatment step with a coupling agent. In the coupling treatment step, by bringing the fluoride phosphor into contact with the coupling agent, a surface treatment layer containing a functional group derived from the coupling agent can be provided on the surface of the fluoride phosphor. This improves the moisture resistance of the fluoride phosphor, for example.

Examples of the functional group derived from the coupling agent include a silyl group having an aliphatic group having 1 to 20 carbon atoms, preferably a silyl group having an aliphatic group having 6 to 12 carbon atoms. . The functional groups derived from the coupling agent may be used alone or in combination of two or more.

Specific examples of the coupling agent include a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, and the like.

The amount of the coupling agent used in the coupling treatment step may be, for example, 0.5% by mass or more and 10% by mass or less based on the mass of the fluoride phosphor. The contact temperature between the fluoride phosphor and the coupling agent may be, for example, 0° C. or more and 70° C. or less. The contact time between the fluoride phosphor and the coupling agent may be, for example, 1 minute or more and 10 hours or less.

A first aspect of the method for producing a fluoride phosphor includes preparing first fluoride particles having an average particle size of 5 μm or more and 30 μm or less, and pulverizing the first fluoride particles to reduce the average particle size. is 0.1 μm or more and 7 μm or less, the maximum particle size is 1 μm or more and 18 μm or less, and the ratio of the maximum particle size to the average particle size is greater than 1.

A second aspect of the method for producing a fluoride phosphor includes preparing first fluoride particles having an average particle size of 5 μm or more and 30 μm or less, and pulverizing the first fluoride particles to obtain a pulverized product. In addition, the pulverized material is surface-treated so that the average particle size is 0.1 μm or more and 7 μm or less, the maximum particle size is 1 μm or more and 18 μm or less, and the ratio of the maximum particle size to the average particle size is greater than 1. obtaining compound particles.

The surface treatment in the method for producing a fluoride phosphor according to the second aspect is performed by mixing the pulverized material and a metal alkoxide containing at least one member selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn in a liquid medium. The method may include contacting the pulverized material with the pulverized material to obtain first oxide-attached fluoride particles having an oxide derived from the metal alkoxide attached to at least a portion of the surface of the pulverized material.

The surface treatment in the method for producing a fluoride phosphor of the second aspect includes contacting the pulverized material with rare earth ions containing at least one selected from the group consisting of La, Ce, Dy, and Gd, and phosphate ions. The method may include obtaining rare earth phosphate-attached fluoride particles to which the rare earth phosphate is attached to at least a portion of the surface of the pulverized material.

The surface treatment in the method for producing a fluoride phosphor of the second aspect includes rare earth phosphate-attached fluoride particles and a metal containing at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn. alkoxide in a liquid medium to obtain second oxide-attached fluoride particles in which an oxide derived from the metal alkoxide is attached to at least a part of the surface of the rare earth phosphate-attached fluoride particles. It may further contain.

Wavelength Conversion Member The wavelength conversion member includes a wavelength conversion layer containing the aforementioned fluoride phosphor and resin. By including the fluoride phosphor described above, the wavelength conversion member can achieve desired chromaticity coordinates in light emission from the light emitting device while reducing the content of the fluoride phosphor. Further, it is possible to configure a wavelength conversion member in which the fluoride phosphor is uniformly distributed. The wavelength conversion layer may be in the form of a sheet, for example, having two main surfaces facing each other and perpendicular to the thickness direction, and a side surface parallel to the thickness direction and surrounding the outer edge of the main surface.

The resin constituting the wavelength conversion layer may be any transparent resin that transmits visible light. Specific examples of the resin include thermosetting resins such as silicone resins and epoxy resins, and photocurable resins such as acrylic resins.

The content of the fluoride phosphor contained in the wavelength conversion layer is adjusted so that the chromaticity coordinate values of light emitted from the light emitting device including the wavelength conversion layer fall within a desired range. Specifically, the content of the fluoride phosphor contained in the wavelength conversion layer may be, for example, 5% by mass or more and 85% by mass or less, preferably 10% by mass or more and 75% by mass or less, based on 100% by mass of the resin. It may be. When the content of the fluoride phosphor is 5% by mass or more, a light emitting device that can emit light with desired chromaticity coordinate values can be easily constructed. Further, when the content of the fluoride phosphor is 85% by mass or less, it is possible to reduce the amount of the fluoride phosphor used and to suppress variations in chromaticity of light emitted from the light emitting device.

The average thickness of the wavelength conversion layer may be, for example, 20 μm or more and 100 μm or less, preferably 30 μm or more and 70 μm or less. Further, the range of variation in the thickness of the wavelength conversion layer may be, for example, 10 μm or less, preferably 5 μm or less. The average thickness of the wavelength conversion layer is calculated as the arithmetic average of thicknesses measured at nine points on an arbitrary cross section in the thickness direction of the wavelength conversion layer. Further, the range of variation in the thickness of the wavelength conversion layer is calculated as the difference between the maximum value and the minimum value of the measured thickness of the wavelength conversion layer.

The wavelength conversion layer may further contain a light emitting material other than the fluoride phosphor. Luminescent materials other than fluoride phosphors may absorb light from a light source and convert the wavelength to light with a different wavelength than that of the fluoride phosphor, or convert the wavelength to light with a similar wavelength. It can be anything.

The luminescent material other than the fluoride phosphor may have an emission peak wavelength in the wavelength range of 495 nm or more and 590 nm or less, and is preferably a β-sialon phosphor, a halosilicate phosphor, a silicate phosphor, or a rare earth aluminate phosphor. The material may be at least one selected from the group consisting of perovskite-based luminescent materials, perovskite-based luminescent materials, and nitride phosphors. The β-sialon phosphor may have a composition represented by the following formula (IIa), for example. The halosilicate phosphor may have a composition represented by the following formula (IIb), for example. The silicate phosphor may have a composition represented by the following formula (IIc), for example. The rare earth aluminate phosphor may have a composition represented by the following formula (IId). The perovskite-based luminescent material may have a composition represented by the following formula (IIe), for example. The nitride phosphor may have a composition represented by the following formula (IIf), (IIg), or (IIh), for example. When the wavelength conversion layer contains a β-sialon phosphor or a perovskite phosphor as a light-emitting material other than a fluoride phosphor, a light-emitting device with a relatively wide range of color reproducibility can be obtained. The wavelength conversion layer contains a halosilicate phosphor, a silicate phosphor, a rare earth aluminate phosphor, or a nitride phosphor as a light-emitting material other than a fluoride phosphor, so that it has high color rendering properties or high luminous efficiency. It can be a light emitting device.

Si _6-t Al _t O _t N _8-t :Eu (IIa)
(In the formula, t is a number that satisfies 0<t≦4.2.)
(Ca, Sr, Ba) ₈ MgSi ₄ O ₁₆ (F, Cl, Br) ₂ :Eu (IIb)
(Ba, Sr, Ca, Mg) ₂ SiO ₄ :Eu (IIc)
(Y, Lu, Gd, Tb) ₃ (Al, Ga) ₅ O ₁₂ :Ce (IId)
CsPb(F, Cl, Br, I) ₃ (IIe)
(La, Y, Gd) ₃ Si ₆ N ₁₁ :Ce (IIf)
(Sr,Ca)LiAl ₃ N ₄ :Eu (IIg)
(Ca,Sr)AlSiN ₃ :Eu (IIh)

In this specification, in the formula representing the composition of a phosphor or luminescent material, multiple elements separated by commas (,) indicate that at least one element among these multiple elements is included in the composition. It means to contain. Furthermore, in the formula representing the composition of the phosphor, the part before the colon (:) represents the host crystal, and the part after the colon (:) represents the activating element.

The average particle size of the luminescent material other than the fluoride phosphor may be, for example, 0.1 μm or more and 7 μm or less, preferably 0.2 μm or more, or 0.5 μm or more. Further, the average particle size may preferably be 5 μm or less, or 3 μm or less. The average particle size of luminescent materials other than fluoride phosphors is measured by the FSSS method.

The wavelength conversion layer may further contain quantum dots in addition to the fluoride phosphor. The quantum dots may absorb light from a light source and convert the wavelength into light with a different wavelength than that of the fluoride phosphor, or may convert the wavelength into light with a similar wavelength. Quantum dots include perovskites having a composition such as (Cs, FA, MA) (Pb, Sn) (Cl, Br, I) ₃ (here, FA means formamidinium and MA means methylammonium). Quantum dots having a structure such as (Ag, Cu, Au) (In, Ga) (S, Se, Te) Quantum dots having a chalcopyrite structure having a composition such as ₂ , (Cd, Zn) (Se, S), etc. semiconductor quantum dots, InP-based semiconductor quantum dots, etc., and may contain at least one selected from the group consisting of these. Here, in the formula expressing the composition of the quantum dot, multiple elements listed separated by commas (,) mean that at least one element among these multiple elements is contained in the composition. do.

The wavelength conversion layer may further contain a light diffusing material in addition to the resin and the fluoride phosphor. By including the light diffusing material, the directivity from the light emitting element can be relaxed and the viewing angle can be increased. Examples of the light diffusing material include silicon oxide, titanium oxide, zinc oxide, zirconium oxide, and aluminum oxide.

The wavelength conversion member may further include a base material that supports the wavelength conversion layer. By including the base material, for example, a wavelength conversion member that is more durable and easier to handle can be constructed. The base material may have, for example, a sheet-like shape that covers the main surface of the wavelength conversion layer. Further, the base material may be placed on one side of the wavelength conversion layer, or may be placed on both sides of the wavelength conversion layer to sandwich the wavelength conversion layer.

Examples of the material of the base material include polyethylene terephthalate resin, acrylic resin, polyester resin, and glass. The base material may further contain the light diffusing material described above. The thickness of the base material may be, for example, 20 μm or more and 200 μm or less, preferably 25 μm or more and 150 μm or less. The base material may be a transparent base material that transmits visible light. The light transmittance of the base material may be, for example, 80% or more in the visible light region, preferably 85% or more.

The base material may have an oxide layer on its surface. When the base material has an oxide layer, the transmittance of oxygen, water vapor, etc. is further reduced, and a wavelength conversion member with more excellent durability can be constructed. Examples of the oxide include silicon oxide and aluminum oxide. The thickness of the oxide layer may be, for example, 0.05 μm or more and 5 μm or less, preferably 0.2 μm or more and 3 μm or less. The oxide layer may be provided on one side or both sides of the base material.

For example, by irradiating the wavelength conversion member with light in a wavelength range of 420 nm or more and 480 nm or less, the wavelength conversion member can emit light in a wavelength range of more than 480 nm and less than 650 nm.

The wavelength conversion member can be manufactured, for example, by the following manufacturing method. A method for manufacturing a wavelength conversion member includes preparing a resin composition containing a fluoride phosphor and an uncured resin raw material, and supplying the prepared resin composition onto one surface of a base material to form a resin composition. The method may include forming a layer, and curing the formed resin composition layer to form a wavelength conversion layer.

Examples of resin raw materials contained in the resin composition include thermosetting silicone resins, epoxy resins, photocurable acrylic monomers, urethane acrylic monomers, and the like. The content of the fluoride phosphor contained in the resin composition may be, for example, 5% by mass or more and 52% by mass or less, preferably 10% by mass or more and 45% by mass or less, based on 100% by mass of the resin raw material. good.

The amount of the resin composition supplied to the base material may be such that, for example, the thickness of the wavelength conversion layer after curing is 20 μm or more and 100 μm or less, preferably 30 μm or more and 70 μm or less. As the supply method, commonly used liquid supply methods such as a comma coater, die coater, bar coater, etc. can be applied. A base material may be laminated on the resin composition layer formed on the base material. This makes it possible to obtain a wavelength conversion member that is more durable.

The method for curing the resin composition layer formed on the base material is, for example, when the resin raw material is thermosetting, heat treatment is performed at a temperature of 140° C. or higher and 160° C. or lower for 2 hours or more and 2.5 hours or less. As a result, a wavelength conversion layer in which the resin composition layer is cured is formed. Further, when the resin raw material is photocurable, a wavelength conversion layer in which the resin composition layer is cured is formed by irradiating it with light in a wavelength range of 350 nm or more and 400 nm or less, for example.

Light-emitting device The light-emitting device includes the wavelength conversion member and the light-emitting element described above. By including the wavelength conversion member containing the above-described fluoride phosphor, it is possible to configure a light emitting device that emits light having predetermined chromaticity coordinates while reducing the amount of fluoride phosphor used. As an example of the structure of a light emitting device, for example, a light emitting device described in Japanese Patent Application Publication No. 2019-186537 and the like can be cited.

The light emitting element may have an emission peak wavelength within a wavelength range of 380 nm or more and 485 nm or less. The light emitting element may be an excitation light source that excites the fluoride phosphor, and the fluoride phosphor is excited by having an emission peak intensity within the range shown below, where the excitation intensity of the fluoride phosphor is relatively large. It becomes easier. The light emitting element preferably has a light emission peak wavelength within a range of 380 nm or more and 480 nm or less, more preferably has a light emission peak wavelength within a range of 410 nm or more and 480 nm or less, and has a light emission peak wavelength within a range of 430 nm or more and 480 nm or less. It is further preferable to have the following. It is preferable to use a semiconductor light emitting device as the light emitting device as the excitation light source. By using a semiconductor light emitting element as an excitation light source, it is possible to obtain a stable light emitting device with high efficiency, high linearity of output with respect to input, and strong resistance to mechanical shock. As the semiconductor light emitting device, for example, a semiconductor light emitting device using a nitride semiconductor can be used. The half width of the emission peak in the emission spectrum of the light emitting element is preferably 30 nm or less, for example.

A light-emitting device includes, for example, a light-emitting element disposed on a substrate, and a wavelength conversion member that converts a portion of light from the light-emitting element into a wavelength and emits the converted light to the outside. The light emitted from the light emitting device is a mixture of light from the light emitting element and light whose wavelength has been converted by the wavelength conversion member.

The present disclosure may include the following aspects.
[1] A fluoride phosphor containing fluoride particles having an average particle size of 0.1 μm or more and 7 μm or less, a maximum particle size of 1 μm or more and 18 μm or less, and a ratio of the maximum particle size to the average particle size of more than 1. The fluoride particles contain an element M containing at least one selected from the group consisting of a group 4 element, a group 13 element, and a group 14 element, an alkali metal, Mn, and F. and the number of moles of the alkali metal is 2, the number of moles of Mn is greater than 0 and less than 0.2, the number of moles of element M is greater than 0.8 and less than 1, and the number of moles of F is greater than 0.8 and less than 1. A fluoride phosphor having a composition in which the number is greater than 5 and less than 7.

[2] The fluoride phosphor according to [1], wherein an inorganic substance other than the fluoride particles is attached to at least a portion of the surface of the fluoride particles.

[3] The inorganic substance is an oxide containing at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn, and at least one selected from the group consisting of La, Ce, Dy, and Gd. The fluoride phosphor according to [2], which contains at least one selected from the group consisting of rare earth phosphates containing one kind of rare earth element.

[4] The fluoride particles include at least one of Si and Ge as the element M in their composition, and when the number of moles of the alkali metal is 2, the total number of moles of Si, Ge, and Mn is 0.9. The fluoride phosphor according to any one of [1] to [3], which has a composition of 1.1 or less.

[5] The fluoride phosphor according to any one of [1] to [4], wherein the fluoride particles have a composition represented by the following formula (1).
A ¹ _c [M ¹ _1-b Mn _b F _d ] (1)
(In formula (1), A ¹ includes at least one selected from the group consisting of Li, Na, K, Rb, and Cs. ^{M 1} includes at least one of Si and Ge, and is a group 4 member. It may further contain at least one element selected from the group consisting of elements and Group 14 elements. b satisfies 0<b<0.2, and c is [M ¹ _1-b Mn _b F _d ] ion is the absolute value of the charge, and d satisfies 5<d<7.)

[6] The fluoride particles contain Si and Al as elements M in their composition, and when the number of moles of the alkali metal is 2, the total number of moles of Si, Al, and Mn is 0.9 or more and 1. 1 or less, and the fluoride phosphor according to any one of [1] to [3], having a composition in which the number of moles of Al is greater than 0 and less than 0.1.

[7] The fluoride phosphor according to any one of [1] to [3] and [6], wherein the fluoride particles have a composition represented by the following formula (2).
A ² _f [M ² _1-e Mn _e F _g ] (2)
(In formula (2), A ² contains at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M ² contains at least Si and Al, and contains a group 4 element, It may further contain at least one element selected from the group consisting of Group 13 elements and Group 14 elements. e satisfies 0<e<0.2, and f is [M ² _1-e Mn _e F _g ] is the absolute value of the charge of the ion, and g satisfies 5<g<7.)

[8] A wavelength conversion member comprising a wavelength conversion layer containing the fluoride phosphor according to any one of [1] to [7] and a resin.

[9] The wavelength conversion member according to [8], wherein the wavelength conversion layer has an average thickness of 20 μm or more and 100 μm or less.

[10] A light-emitting device comprising the wavelength conversion member according to [8] or [9] and a light-emitting element having an emission peak wavelength within a wavelength range of 380 nm or more and 485 nm or less.

[11] Preparing first fluoride particles having an average particle size of 5 μm or more and 30 μm or less, and pulverizing the first fluoride particles so that the average particle size is 0.1 μm or more and 7 μm or less, A method for producing a fluoride phosphor, comprising: obtaining second fluoride particles having a maximum particle size of 1 μm or more and 18 μm or less, and a ratio of the maximum particle size to the average particle size of more than 1.

[12] The method for producing a fluoride phosphor according to [11], further comprising surface-treating a pulverized product obtained by pulverizing the first fluoride particles.

[13] The surface treatment is performed by bringing the pulverized product into contact with a metal alkoxide containing at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn in a liquid medium. The method for producing a fluoride phosphor according to [12], which includes obtaining first oxide-attached fluoride particles to which an oxide derived from the metal alkoxide is attached to at least a part of the surface of the object.

[14] The surface treatment is performed by bringing the pulverized material into contact with rare earth ions containing at least one selected from the group consisting of La, Ce, Dy, and Gd, and phosphate ions. The method for producing a fluoride phosphor according to [12], which includes obtaining rare earth phosphate-attached fluoride particles to which a rare earth phosphate is attached to at least a portion of the surface.

[15] The surface treatment involves treating the rare earth phosphate-attached fluoride particles and a metal alkoxide containing at least one member selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn in a liquid medium. further comprising obtaining second oxide-attached fluoride particles in which an oxide derived from the metal alkoxide is attached to at least a portion of the surface of the rare earth phosphate-attached fluoride particles by contacting them [14] A method for producing a fluoride phosphor as described in .

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

The average particle size of the fluoride phosphors obtained in the following Examples and Comparative Examples was measured using Fisher Sub-Sieve Sizer Model 95 manufactured by Fisher Scientific. Moreover, the maximum particle size was measured as follows in a scanning electron microscope (SEM) image. An SEM image in which approximately 500 or more fluoride phosphor particles were observed was obtained at an accelerating voltage of 5 kV and a magnification of 250 times. Further enlarged SEM images of each of a plurality of particles estimated to have the maximum particle size among them were obtained. The magnification at this time is approximately 5000 times. The maximum length of each of these plural particles was measured from the scale of the SEM image that had been calibrated in advance. The maximum lengths of the measured particles were compared, and the maximum length of the particle giving the maximum value was taken as the maximum particle size of the fluoride particles. Furthermore, compositional analysis was performed by inductively coupled plasma optical emission spectroscopy (ICP-AES).

Example 1a
A first solution was prepared by weighing 916.3 g of K ₂ MnF ₆ and dissolving it in 12.0 L of a 55% by mass hydrofluoric acid aqueous solution. Further, 7029 g of KHF ₂ was weighed and dissolved in 23.5 L of a 55% by mass hydrofluoric acid aqueous solution to prepare a second solution. Subsequently, 15.5 L of an aqueous solution containing 40% by mass of H ₂ SiF ₆ was prepared and used as a third solution. While stirring the second solution at room temperature, the first solution and the third solution were added dropwise over about 20 hours. After completing the dropping, add 400 mL of 35% hydrogen peroxide solution, add 30 L of pure water, stir, leave to stand, and remove the supernatant liquid several times for washing. After solid-liquid separation of the resulting precipitate, Fluoride particles were manufactured by washing with ethanol and drying at 90° C. for 10 hours.

The obtained fluoride particles were heat-treated at a temperature of 500°C and a holding time of 8 hours while being brought into contact with fluorine gas in an atmosphere with a fluorine gas concentration of 20% by volume and a nitrogen gas concentration of 80% by volume. The fluoride phosphor of Example 1a was manufactured. Note that the holding time in heat treatment is the time elapsed from when a predetermined heat treatment temperature is reached until heating is stopped.

The obtained fluoride phosphor of Example 1a had an average particle size of 5.6 μm and a maximum particle size of 15.0 μm. Further, it had a composition represented by K ₂ Si _0.962 Mn _0.038 F ₆ .

Example 1b
Regarding the fluoride phosphor of Example 1a, while stirring 300 g of the fluoride phosphor in 900 g of a 0.12 mass % phosphoric acid aqueous solution, 180 g of a 1.5 mass % lanthanum nitrate aqueous solution was added dropwise over about 1 minute. By doing so, lanthanum phosphate was attached to the surface to obtain a surface-treated fluoride phosphor of Example 1b. The amount of attached lanthanum phosphate was 1.9% by mass based on the fluoride phosphor.

The fluoride phosphor of Example 1b after surface treatment had an average particle size of 5.2 μm and a maximum particle size of 13.6 μm.

Example 2a
The same procedure as in Example 1 was carried out, except that the amount of K ₂ MnF ₆ used was changed to 1047.2 g, and the amount of 55% by mass hydrofluoric acid aqueous solution of the second solution was changed to 28.5 L. Fluoride particles were obtained. The obtained fluoride particles had an average particle size of 9.0 μm and a composition expressed as K ₂ Si _0.950 Mn _0.050 F ₆ .

The obtained fluoride particles were placed in a cylindrical polypropylene bottle with a capacity of about 2000 mL containing 2000 g of alumina balls with a diameter of 1 mm, pure water was added until the alumina balls were completely submerged, and then pulverized using a wet ball mill for 10 minutes. Time went. The amount of fluoride particles charged was 12.5% by mass of the alumina balls. The slurry of the pulverized product obtained by separating the alumina balls after ball milling was separated into solid and liquid, washed with ethanol, and dried at 90° C. for 10 hours to obtain the fluoride phosphor of Example 2a.

The obtained fluoride phosphor of Example 2a has an average particle size of 1.2 μm, a maximum particle size of 7.0 μm, and a composition represented by K ₂ Si _0.962 Mn _0.038 F ₆ It had

Example 2b
Example 1b except that the concentration of the phosphoric acid aqueous solution was changed to 0.007% by mass and the concentration of the lanthanum nitrate aqueous solution was changed to 0.083% by mass for the fluoride phosphor of Example 2a after the pulverization treatment. A fluoride phosphor of Example 2b was obtained in which 0.2% by mass of lanthanum phosphate was attached to the fluoride phosphor.

The fluoride phosphor of Example 2b after surface treatment had an average particle size of 1.2 μm and a maximum particle size of 7.0 μm.

Example 3a
The amount of K ₂ MnF ₆ used was changed to 1963.2 g, the amount of 55 mass % hydrofluoric acid aqueous solution of the first solution was changed to 15.5 L, and the amount of 55 mass % of the second solution was changed to 15.5 L. Fluoride particles were obtained in the same manner as in Example 1a, except that the amount of the hydrofluoric acid aqueous solution used was changed to 28.5 L and the dropping rate of the first solution was doubled. The obtained fluoride particles had an average particle size of 9.5 μm and a composition expressed as K ₂ Si _0.906 Mn _0.094 F ₆ .

The obtained fluoride particles were pulverized in the same manner as in Example 2a to obtain the fluoride phosphor of Example 3a.

The obtained fluoride phosphor of Example 3a had an average particle size of 1.1 μm, a maximum particle size of 3.0 μm, and a composition represented by K ₂ Si _0.922 Mn _0.078 F ₆ It had

Example 3b
The fluoride phosphor of Example 3a after the pulverization treatment was surface-treated in the same manner as in Example 2b, and the fluoride of Example 3b had 0.3% by mass of lanthanum phosphate attached to the fluoride phosphor. A phosphor was obtained.

The fluoride phosphor of Example 3b after surface treatment had an average particle size of 1.1 μm and a maximum particle size of 5.0 μm.

Example 4a
_The process was carried out in the same manner as in Example _1a except that the amount of the 55% by mass hydrofluoric acid aqueous solution used in the second solution was changed to _{28.5 L.} Fluoride particles having the following composition were obtained. The obtained fluoride particles and a fluoride having a composition represented by K ₃ AlF ₆ were mixed to obtain a mixture. At this time, they were mixed so that the ratio of the number of moles of fluoride to the number of moles of fluoride particles was 0.009. The obtained mixture was heat-treated in an inert gas atmosphere having a nitrogen gas concentration of 100% by volume at a temperature of 700° C. and a holding time of 5 hours to obtain a first heat-treated product. The obtained first heat-treated product was thoroughly washed with washing water containing 1% by mass of hydrogen peroxide. The first heat-treated product after cleaning is heat-treated at a temperature of 500° C. and a holding time of 8 hours while being brought into contact with fluorine gas in an atmosphere with a fluorine gas concentration of 20% by volume and a nitrogen gas concentration of 80% by volume. was carried out to obtain fluoride particles having the second composition.

The obtained fluoride particles having the second composition have an average particle size of 10.4 μm, a maximum particle size of 15.2 μm, and K ₂ Si _0.956 Al _0.007 Mn _0.037 F _5. It had a composition represented by ₉₉₂ .

The obtained fluoride particles having the second composition were pulverized in the same manner as in Example 2a to obtain the fluoride phosphor of Example 4a.

The obtained fluoride phosphor of Example 4a had an average particle size of 1.3 μm and a maximum particle size of 4.2 μm.

Example 4b
The fluoride phosphor of Example 4a after the pulverization treatment was subjected to surface treatment in the same manner as in Example 1b to produce the fluoride of Example 4b in which 0.2% by mass of lanthanum phosphate was attached to the fluoride phosphor. A phosphor was obtained.

The fluoride phosphor of Example 4b after surface treatment had an average particle size of 1.3 μm and a maximum particle size of 7.0 μm.

Comparative example 1a
The same procedure as in Example 1a was carried out, except that the amount of K ₂ MnF ₆ used was changed to 850.9 g, and the amount of 55% by mass hydrofluoric acid aqueous solution of the second solution was changed to 28.5 L. , a fluoride phosphor of Comparative Example 1a was obtained.

The fluoride phosphor of Comparative Example 1a had an average particle size of 8.9 μm, a maximum particle size of 26.0 μm, and had a composition represented by K ₂ Si _0.961 Mn _0.039 F ₆ was.

Comparative example 1b
The obtained fluoride phosphor of Comparative Example 1a was the same as Example 1b except that the concentration of the phosphoric acid aqueous solution was changed to 0.24% by mass and the concentration of the lanthanum nitrate aqueous solution was changed to 3.0% by mass. A fluoride phosphor of Comparative Example 1b, in which 2.5% by mass of lanthanum phosphate was attached to the fluoride phosphor, was obtained by surface treatment in the same manner.

The fluoride phosphor after surface treatment had an average particle size of 7.5 μm and a maximum particle size of 24.6 μm.

Comparative example 2a
The fluoride particles having the second composition before the pulverization treatment obtained in Example 4a were used as the fluoride phosphor of Comparative Example 2a.

Comparative example 2b
The fluoride phosphor of Comparative Example 2a was surface-treated in the same manner as Comparative Example 1b to obtain the fluoride phosphor of Comparative Example 2b in which 0.5% by mass of lanthanum phosphate was attached to the fluoride phosphor. Ta.

The fluoride phosphor of Comparative Example 2b after surface treatment had an average particle size of 10.4 μm and a maximum particle size of 18.6 μm.

Example 5a
A first solution was prepared by weighing 916.3 g of K ₂ MnF ₆ and dissolving it in 12.0 L of a 55% by mass hydrofluoric acid aqueous solution. Further, 7029 g of KHF ₂ was weighed and dissolved in 23.5 L of a 55% by mass hydrofluoric acid aqueous solution to prepare a second solution. Subsequently, 15.5 L of an aqueous solution containing 40% by mass of H ₂ SiF ₆ was prepared and used as a third solution. While stirring the second solution at room temperature, the first solution and the third solution were added dropwise over about 20 hours. After the dropwise addition was completed, 400 mL of 35% hydrogen peroxide solution was added, 30 L of pure water was added, stirred, left to stand, and the supernatant liquid removed several times for washing. After solid-liquid separation of the resulting precipitate, Fluoride particles were manufactured by washing with ethanol and drying at 90° C. for 10 hours.

The obtained fluoride particles were heat-treated at a temperature of 500°C and a holding time of 8 hours while being brought into contact with fluorine gas in an atmosphere with a fluorine gas concentration of 20% by volume and a nitrogen gas concentration of 80% by volume. A fluoride phosphor of Example 5a was prepared. Note that the holding time in heat treatment is the time elapsed from when a predetermined heat treatment temperature is reached until heating is stopped.

The obtained fluoride phosphor of Example 5a had an average particle size of 5.6 μm and a maximum particle size of 15.0 μm. Moreover, it had a composition represented by K ₂ Si _0.961 Mn _0.039 F ₆ .

Example 5b
Regarding the fluoride phosphor of Example 5a, while stirring 300 g of the fluoride phosphor in 900 g of a 0.12 mass % phosphoric acid aqueous solution, 180 g of a 1.5 mass % lanthanum nitrate aqueous solution was added dropwise over about 1 minute. By doing so, lanthanum phosphate was attached to the surface to obtain a surface-treated fluoride phosphor of Example 5b. The amount of attached lanthanum phosphate was 1.9% by mass based on the fluoride phosphor.

The fluoride phosphor of Example 5b after surface treatment had an average particle size of 5.2 μm and a maximum particle size of 13.6 μm.

Example 6a
The same procedure as in Example 5a was carried out, except that the amount of K ₂ MnF ₆ used was changed to 1047.2 g, and the amount of the 55 mass % hydrofluoric acid aqueous solution of the second solution was changed to 28.5 L. Fluoride particles were obtained. The obtained fluoride particles had an average particle size of 8.3 μm and a composition expressed as K ₂ Si _0.949 Mn _0.051 F ₆ .

The obtained fluoride particles were placed in a cylindrical polypropylene bottle with a capacity of about 2000 mL containing 2000 g of alumina balls with a diameter of 1 mm, pure water was added until the alumina balls were completely submerged, and then pulverized using a wet ball mill for 10 minutes. Time went. The amount of fluoride particles charged was 12.5% by mass of the alumina balls. The slurry of the ground material obtained by separating the alumina balls after ball milling was separated into solid and liquid, washed with ethanol, and dried at 90° C. for 10 hours to obtain the fluoride phosphor of Example 6a.

The obtained fluoride phosphor of Example 6a had an average particle size of 1.2 μm, a maximum particle size of 7.0 μm, and a composition represented by K ₂ Si _0.961 Mn _0.039 F ₆ It had

Example 6b
Example 5b except that the concentration of the phosphoric acid aqueous solution was changed to 0.007% by mass and the concentration of the lanthanum nitrate aqueous solution was changed to 0.083% by mass with respect to the fluoride phosphor of Example 6a after the pulverization treatment. A fluoride phosphor of Example 6b was obtained in which lanthanum phosphate was attached in an amount of 0.2% by mass based on the fluoride phosphor.

The fluoride phosphor of Example 6b after surface treatment had an average particle size of 1.2 μm and a maximum particle size of 7.0 μm.

Example 7a
The amount of K ₂ MnF ₆ used was changed to 1963.2 g, the amount of 55 mass % hydrofluoric acid aqueous solution of the first solution was changed to 15.5 L, and the amount of 55 mass % of the second solution was changed to 15.5 L. Fluoride particles were obtained in the same manner as in Example 5a, except that the amount of the hydrofluoric acid aqueous solution used was changed to 28.5 L and the dropping rate of the first solution was doubled. The obtained fluoride particles had an average particle size of 9.5 μm and a composition expressed as K ₂ Si _0.902 Mn _0.098 F ₆ .

The obtained fluoride particles were pulverized in the same manner as in Example 6a to obtain a fluoride phosphor of Example 7a.

The obtained fluoride phosphor of Example 7a had an average particle size of 1.1 μm, a maximum particle size of 3.0 μm, and a composition represented by K ₂ Si _0.920 Mn _0.080 F ₆ It had

Example 7b
The fluoride phosphor of Example 7a after the pulverization treatment was subjected to surface treatment in the same manner as in Example 6b to obtain the fluoride of Example 7b in which 0.3% by mass of lanthanum phosphate was attached to the fluoride phosphor. A phosphor was obtained.

The fluoride phosphor of Example 7b after surface treatment had an average particle size of 1.1 μm and a maximum particle size of 5.0 μm.

Example 8a
K ₂ Si _0.955 Mn _0.045 F ₆ was prepared in the same manner as in Example 5a except that the amount of the 55% by mass hydrofluoric acid aqueous solution used in the second solution was changed to 28.5 L. Fluoride particles having the following composition were obtained. The obtained fluoride particles and a fluoride having a composition represented by K ₃ AlF ₆ were mixed to obtain a mixture. At this time, the mixture was mixed so that the ratio of the number of moles of fluoride to the number of moles of fluoride particles was 0.009. The obtained mixture was heat-treated in an inert gas atmosphere having a nitrogen gas concentration of 100% by volume at a temperature of 700° C. and a holding time of 5 hours to obtain a first heat-treated product. The obtained first heat-treated product was thoroughly washed with washing water containing 1% by mass of hydrogen peroxide. The first heat-treated product after cleaning is heat-treated at a temperature of 500° C. and a holding time of 8 hours while being brought into contact with fluorine gas in an atmosphere with a fluorine gas concentration of 20 volume % and a nitrogen gas concentration of 80 volume %. This was carried out to obtain fluoride particles having the second composition.

The obtained fluoride particles having the second composition have an average particle size of 10.4 μm, a maximum particle size of 15.2 μm, and K ₂ Si _0.955 Al _0.007 Mn _0.038 F _5. It had a composition represented by ₉₉₃ .

The obtained fluoride particles having the second composition were pulverized in the same manner as in Example 6a to obtain a fluoride phosphor of Example 8a.

The obtained fluoride phosphor of Example 8a had an average particle size of 1.3 μm and a maximum particle size of 4.2 μm.

Example 8b
The fluoride phosphor of Example 8a after the pulverization treatment was surface-treated in the same manner as in Example 6b, and the fluoride of Example 8b had 0.2% by mass of lanthanum phosphate attached to the fluoride phosphor. A phosphor was obtained.

The fluoride phosphor of Example 8b after surface treatment had an average particle size of 1.3 μm and a maximum particle size of 7.0 μm.

Example 9a
The amount of K ₂ MnF ₆ used was changed to 458.2 g, the amount of 55 mass % hydrofluoric acid aqueous solution of the first solution was changed to 6.0 L, and the amount of 55 mass % of the second solution was changed. Example 5a except that the amount of the aqueous hydrofluoric acid solution used was changed to 20.0 L, and the amount of the aqueous solution containing 40% by mass of H ₂ SiF ₆ as the third solution was changed to 7.8 L. In the same manner, fluoride particles A having a composition represented by K ₂ Si _0.948 Mn _0.052 F ₆ were obtained. The obtained fluoride particles A and fluoride particles B having a composition represented by K ₃ AlF ₆ were mixed to obtain a mixture. At this time, they were mixed so that the ratio of the number of moles of fluoride particles B to the number of moles of fluoride particles A was 0.010. The obtained mixture was heat-treated in an inert gas atmosphere having a nitrogen gas concentration of 100% by volume at a temperature of 700° C. and a holding time of 5 hours to obtain a first heat-treated product. The obtained first heat-treated product was thoroughly washed with washing water containing 1% by mass of hydrogen peroxide. The first heat-treated product after cleaning is heat-treated at a temperature of 500° C. and a holding time of 8 hours while being brought into contact with fluorine gas in an atmosphere with a fluorine gas concentration of 20% by volume and a nitrogen gas concentration of 80% by volume. A fluoride phosphor of Example 9a having the second composition was obtained.

The obtained fluoride phosphor of Example 9a had an average particle size of 6.2 μm, a maximum particle size of 10.0 μm, and a composition of K ₂ Si _0.954 Al _0.009 Mn _0.037 F _5. It had a composition represented by ₉₉₁ .

Example 9b
The fluoride phosphor of Example 9a was surface-treated in the same manner as in Example 5b to obtain the fluoride phosphor of Example 9b in which 2.3% by mass of lanthanum phosphate was attached to the fluoride phosphor. Ta.

The fluoride phosphor of Example 9b after surface treatment had an average particle size of 5.9 μm and a maximum particle size of 13.0 μm.

Comparative example 3a
The same procedure as in Example 5a was carried out, except that the amount of K ₂ MnF ₆ used was changed to 850.9 g, and the amount of the 55% by mass hydrofluoric acid aqueous solution of the second solution was changed to 28.5 L. , a fluoride phosphor of Comparative Example 3a was obtained.

The fluoride phosphor of Comparative Example 3a had an average particle size of 8.9 μm, a maximum particle size of 26.0 μm, and a composition expressed as K ₂ Si _0.960 Mn _0.040 F ₆ was.

Comparative example 3b
The obtained fluoride phosphor of Comparative Example 3a was the same as Example 5b except that the concentration of the phosphoric acid aqueous solution was changed to 0.24% by mass and the concentration of the lanthanum nitrate aqueous solution was changed to 3.0% by mass. The surface was treated in the same manner to obtain a fluoride phosphor of Comparative Example 3b in which 2.3% by mass of lanthanum phosphate was attached to the fluoride phosphor.

The fluoride phosphor after surface treatment had an average particle size of 7.5 μm and a maximum particle size of 24.6 μm.

Comparative example 4a
The fluoride particles having the second composition before the pulverization treatment obtained in Example 8a were used as the fluoride phosphor of Comparative Example 4a.

Comparative example 4b
The fluoride phosphor of Comparative Example 4a was surface-treated in the same manner as Comparative Example 3b to obtain the fluoride phosphor of Comparative Example 4b in which 0.5% by mass of lanthanum phosphate was attached to the fluoride phosphor. Ta.

The fluoride phosphor of Comparative Example 4b after surface treatment had an average particle size of 10.4 μm and a maximum particle size of 18.6 μm.

Evaluation of Mn content The composition of each fluoride phosphor of Examples and Comparative Examples before surface treatment was analyzed by inductively coupled plasma emission spectroscopy (ICP-AES) to measure the Mn content, and the following The molar ratio (variable b) or (variable e) of Mn in 1 mole of the composition expressed by formula (1a) or formula (1b) was determined. The results are shown in Table 1.
K ₂ [M ¹ _1-b Mn _b F _d ] (1a)
K ₂ [M ² _{1-e Mne} F _g ] (1b)

Powder brightness For the powder of the fluoride phosphor obtained above, using a spectrofluorometer (manufactured by Otsuka Electronics Co., Ltd., QE-2000), excitation light with an emission peak wavelength of 450 nm was applied to each fluoride phosphor powder. The fluoride was irradiated and the emission spectrum of each fluoride phosphor at room temperature (25° C.) was measured. From the emission spectrum data measured for each fluoride phosphor of Examples and Comparative Examples, the emission brightness of the fluoride phosphor obtained in Comparative Example 1a or 1b was set as 100%, and Examples 1a to 4a and Comparative Example The emission brightness of the fluoride phosphors of Example 2a, Examples 1b to 4b, and Comparative Example 2b was calculated as relative brightness. In addition, regarding the luminance of the fluoride phosphors of Examples 5a to 9a and Comparative Example 4a, Examples 5b to 9b, and Comparative Example 4b, the luminance of the fluoride phosphor obtained in Comparative Example 3a or 3b, respectively. It was calculated as a relative brightness set to 100%. The results are shown in Tables 1 to 4.

SEM Image A SEM image of the fluoride phosphor was obtained using a scanning electron microscope (SEM). FIG. 1 shows a SEM image explaining the method for measuring the maximum length of fluoride particles, and FIG. 2 shows an enlarged SEM image explaining the method for measuring the maximum length of fluoride particles. Further, FIG. 3 shows a SEM image of the fluoride phosphor obtained in Comparative Example 1b, FIG. 4 shows an SEM image of the fluoride phosphor obtained in Example 1b, and FIG. 5 shows a SEM image of the fluoride phosphor obtained in Example 2b. A SEM image of the fluoride phosphor is shown.

The surface-treated fluoride phosphor obtained above, 182 parts by mass of the acrylic resin raw material, and a photopolymerization initiator were mixed to obtain a composition. The obtained composition was applied to a polyethylene terephthalate film having a thickness of 50 μm to form a composition layer, and another identical film was superimposed on the composition layer. Thereafter, the acrylic resin raw material was polymerized and cured by irradiation with ultraviolet rays. Thereby, a wavelength conversion member having a total thickness of 180 μm was obtained, in which a sheet-shaped wavelength conversion layer containing a fluoride phosphor and a cured resin and having a thickness of 80 μm was sandwiched between two polyethylene terephthalate films. In preparing the composition, the amount of the fluoride phosphor used was adjusted so that the x value of the CIE chromaticity coordinate of the light emitted by the light emitting device including the resulting wavelength conversion member was approximately 0.24. Table 3 shows the amount of fluoride phosphor used. In Table 3, for example, the light emitting device using the fluoride phosphor of Example 1b is shown as the light emitting device of Example 1, and other Examples and Comparative Examples are shown in the same manner. The amount of the fluoride phosphor used in Examples 1 to 4 and Comparative Example 2 is a relative value based on the amount used in Comparative Example 1 as 100 parts by mass. Further, the amounts used in Examples 5 to 9 and Comparative Example 4 are relative values based on the amount used in Comparative Example 3 as 100 parts by mass.

A blue LED (emission peak wavelength: 450 nm), which is a semiconductor light emitting element, was placed under the obtained wavelength conversion member to obtain a light emitting device. The luminance of the obtained light emitting device was measured using a spectrophotometer. Regarding the brightness, the brightness of the light emitting devices of Examples 1 to 4 and Comparative Example 2 was expressed as relative brightness (%) with the brightness of the light emitting device of Comparative Example 1 as 100%. Furthermore, the brightness of the light emitting devices of Examples 5 to 9 and Comparative Example 4 was expressed as relative brightness (%) with the brightness of the light emitting device of Comparative Example 3 as 100%. The results are shown in Table 3.

By using the fluoride phosphors of Examples 1b and 2b, the amount of phosphor used could be reduced compared to using the fluoride phosphor of Comparative Example 1b. In Example 3b, the amount of fluoride phosphor used could be further reduced than in Example 2b. By using the fluoride phosphor of Example 4b, the amount of phosphor used could be reduced compared to using the fluoride phosphor of Comparative Example 2b. Further, even if the particle size was smaller than that of the comparative example, a relative brightness of 90% or more could be maintained. Note that due to the smaller average particle size and maximum particle size, the brightness as a powder is about 40% lower in the example than in the comparative example, but by using it as a light emitting device, the brightness is lower than that of the comparative example. It can be seen that the decrease is suppressed to about 7% at maximum in the example.

By using the fluoride phosphors of Examples 5b and 6b, the amount of phosphor used could be reduced compared to using the fluoride phosphor of Comparative Example 3b. In Example 7b, the amount of fluoride phosphor used could be further reduced than in Example 6b. By using the fluoride phosphor of Example 8b, the amount of phosphor used could be reduced compared to using the fluoride phosphor of Comparative Example 4b. Further, even if the particle size was smaller than that of the comparative example, a relative brightness of 90% or more could be maintained. Note that due to the smaller average particle size and maximum particle size, the brightness as a powder is about 40% lower in the example than in the comparative example, but by using it as a light emitting device, the brightness is lower than that of the comparative example. It can be seen that the decrease is suppressed to about 7% at maximum in the example.

The fluoride phosphor according to the present disclosure can be used particularly in a light emitting device using a light emitting diode as an excitation light source, for example, a light source for illumination, a light source for an LED display or a liquid crystal backlight, a traffic light, an illuminated switch, various sensors, etc. It can be suitably used for various indicators, small strobes, etc.

Claims (15)

A fluoride phosphor containing fluoride particles having an average particle size of 0.5 μm or more and 3 μm or less, a maximum particle size of 1 μm or more and 10 μm or less, and a ratio of the maximum particle size to the average particle size of 2 or more and 6 or less. and
The fluoride particles contain an element M containing at least one selected from the group consisting of a group 4 element, a group 13 element, and a group 14 element, an alkali metal, Mn, and F; When the number of moles of metal is 2, the number of moles of Mn is 0.038 or more and 0.08 or less , the number of moles of element M is more than 0.8 and less than 1, and the number of moles of F is 5. A fluoride phosphor having a composition greater than 7 and less than 7. The fluoride phosphor according to claim 1, wherein an inorganic substance other than the fluoride particles is attached to at least a part of the surface of the fluoride particles. The inorganic substance is an oxide containing at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn, and at least one selected from the group consisting of La, Ce, Dy, and Gd. The fluoride phosphor according to claim 2, containing at least one member selected from the group consisting of rare earth phosphates containing rare earth elements. The fluoride particles include at least one of Si and Ge as the element M in their composition, and when the number of moles of the alkali metal is 2, the total number of moles of Si, Ge, and Mn is 0.9 or more and 1. The fluoride phosphor according to claim 1, having a composition of 1 or less. The fluoride phosphor according to claim 1, wherein the fluoride particles have a composition represented by the following formula (1).
A ¹ _c [M ¹ _1-b Mn _b F _d ] (1)
(In formula (1), A ¹ includes at least one selected from the group consisting of Li, Na, K, Rb, and Cs. ^{M 1} includes at least one of Si and Ge, and is a group 4 member. It may further contain at least one element selected from the group consisting of elements and Group 14 elements. b satisfies 0.015≦b≦0.1, and c is [M ¹ _1-b Mn _b F _d ] is the absolute value of the charge of the ion, and d satisfies 5<d<7.) The fluoride particles contain Si and Al as elements M in their composition, and when the number of moles of the alkali metal is 2, the total number of moles of Si, Al, and Mn is 0.9 or more and 1.1 or less. The fluoride phosphor according to claim 1, having a composition in which the number of moles of Al exceeds 0 and is 0.1 or less. The fluoride phosphor according to claim 1, wherein the fluoride particles have a composition represented by the following formula (2).
A ² _f [M ² _1-e Mn _e F _g ] (2)
(In formula (2), A ² contains at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M ² contains at least Si and Al, and contains a group 4 element, It may further contain at least one element selected from the group consisting of Group 13 elements and Group 14 elements. e satisfies 0.015≦ e ≦0.1, and f [M ² _1−e Mn _e F _g ] is the absolute value of the charge of the ion, and g satisfies 5<g<7.) A wavelength conversion member comprising a wavelength conversion layer containing the fluoride phosphor according to claim 1 and a resin. The wavelength conversion member according to claim 8, wherein the average thickness of the wavelength conversion layer is 20 μm or more and 100 μm or less. A light-emitting device comprising the wavelength conversion member according to claim 8 and a light-emitting element having an emission peak wavelength within a wavelength range of 380 nm or more and 485 nm or less. preparing first fluoride particles having an average particle size of 5 μm or more and 30 μm or less;
The first fluoride particles are pulverized to have an average particle size of 0.5 μm or more and 3 μm or less, a maximum particle size of 1 μm or more and 10 μm or less, and a ratio of the maximum particle size to the average particle size of 2 or more and 6 or less. obtaining second fluoride particles that are
The second fluoride particles contain an element M containing at least one selected from the group consisting of a group 4 element, a group 13 element, and a group 14 element, an alkali metal, Mn, and F. and the number of moles of the alkali metal is 2, the number of moles of Mn is 0.038 or more and 0.08 or less , the number of moles of element M is more than 0.8 and less than 1, and the number of moles of F is A method for producing a fluoride phosphor having a composition in which the number is greater than 5 and less than 7. The method for producing a fluoride phosphor according to claim 11, further comprising surface-treating a pulverized product obtained by pulverizing the first fluoride particles. The surface treatment includes contacting the pulverized material with a metal alkoxide containing at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn in a liquid medium to treat the surface of the pulverized material. 13. The method for producing a fluoride phosphor according to claim 12, comprising obtaining first oxide-attached fluoride particles to which an oxide derived from the metal alkoxide is attached to at least a portion of the fluoride particles. The surface treatment includes bringing the pulverized material into contact with rare earth ions containing at least one selected from the group consisting of La, Ce, Dy, and Gd, and phosphate ions to improve at least the surface of the pulverized material. 13. The method for producing a fluoride phosphor according to claim 12, comprising obtaining rare earth phosphate-attached fluoride particles to which rare earth phosphate is attached. The surface treatment includes contacting the rare earth phosphate-attached fluoride particles with a metal alkoxide containing at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn in a liquid medium. 15. The method according to claim 14, further comprising obtaining second oxide-attached fluoride particles in which an oxide derived from the metal alkoxide is attached to at least a portion of the surface of the rare earth phosphate-attached fluoride particles. Method for producing fluoride phosphor.