TW202231834A - Phosphor particle, luminescence device, image displaying apparatus and method for manufacturing phosphor particle - Google Patents

Abstract

A phosphor particle of the invention has a core composed of a crystalline phosphor having a composition represented by Sr(Li1+x, Al3-x)(O2xN4-2x):Eu(0<x≤2), and the surface of the core is coated with a layer that contains polysiloxane bonds.

Description

Phosphor particles, method for producing the same, light-emitting device, and image display device

The present invention relates to phosphor particles, a method for producing the phosphor particles, a light-emitting device, and an image display device.

In recent years, since high color reproducibility has been strongly demanded for LEDs for liquid crystal displays and lighting applications, phosphors that emit light with as narrow a full width at half maximum of an emission peak portion as possible are desired. For example, white LEDs used in liquid crystal displays need to emit green phosphors or red phosphors that emit light with a narrow full-width at half-maximum at the luminous peak. Narrow-band green phosphors and narrow-band red phosphors of light at the luminous peak. In addition, in lighting applications requiring high brightness, a narrow-band yellow phosphor that emits light with a narrow full-width at half maximum at the luminous peak portion is required.

As an example of a narrow-band green phosphor, a green phosphor obtained by activating β-type silicon-aluminum oxynitride as a parent crystal and activating it with Eu atoms is known, that is, β-type silicon-aluminum oxynitride. Phosphor (refer to Patent Document 1, in this specification, a crystal such as the above-mentioned β-type silico-aluminum oxynitride is referred to as a "phosphor parent crystal". It is also abbreviated as a "parent crystal" in some cases). It is known that the β-type silicon aluminum oxynitride phosphor changes the oxygen content while maintaining the crystal structure, so that the wavelength of the emission peak portion is shifted to the shorter wavelength side (for example, refer to Patent Document 2). In addition, it is known that when β-type silicon-aluminum oxynitride is activated with Ce atoms, it becomes a phosphor that emits blue light (for example, refer to Patent Document 3). In addition, as an example of a narrow-band red phosphor, a phosphor obtained by crystallizing SrLiAl ₃ N ₄ as a phosphor precursor and activating it with Eu atoms is known (see Non-Patent Document 1).

Here, atoms that control light emission such as Eu atoms and Ce atoms are referred to as activated atoms. Generally speaking, the activated atoms exist in the state of ions in the phosphor, and exist to replace a part of the atoms in the phosphor precursor crystal.

Therefore, the fluorescent system determines the luminescent color by the combination of the phosphor precursor crystal and the activated atoms that replace it. In addition, the combination of phosphor matrix crystals and activated atoms will determine the luminescence spectrum, excitation spectrum and other luminescence characteristics, chemical stability, or thermal stability, so the situation of different phosphor matrix crystals or activated atoms are different. In this case, it is regarded as a different phosphor. In addition, even if the chemical composition is the same, if the crystal structure of the phosphor precursor crystals is different, the luminescent properties and chemical stability are different, so they are regarded as different phosphors.

On the other hand, since the phosphor is unstable to the external environment, it is known to coat the phosphor with other inorganic substances in order to prevent deterioration over time. For example, Patent Document 4 discloses that when Eu _a Sr _b LiAl _c N _d (0<a≦0.2, 0.8≦b≦1.2, 2.4≦c≦3.6, 3.2≦d≦4.8) is used as the phosphor matrix crystal and A technique for forming a coating film containing a compound formed of silicon atoms and oxygen atoms in phosphors obtained by activating Eu atoms. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2005-255895 Patent Document 2: International Publication No. 2007/066733 Patent Document 3: International Publication No. 2006/101096 Patent Document 4: Japanese Patent Laid-Open No. 2017-214516 [Non-patent literature]

Non-Patent Document 1: NATURE MATERIALS VOL. 13 SEPTEMBER 2014

[The problem to be solved by the invention]

Among the deterioration of the phosphor over time, moisture resistance and water resistance are important in terms of maintaining the quality of the phosphor. In recent years, the requirements for quality improvement of LEDs (light emitting diodes) have gradually increased, and durability such as moisture resistance and water resistance are required to be further improved.

On the other hand, as described above, the luminescence characteristics such as the luminescence spectrum and excitation spectrum are determined by the combination of the phosphor matrix crystal and the activated atoms. Therefore, the method of maintaining the individual luminescence characteristics of the phosphor and improving the durability also depends on The phosphor precursor crystals vary.

Therefore, the inventors of the present application once again focused on a phosphor having a crystal structure different from the parent crystal of the phosphor having the crystal structure _disclosed in Patent _{Document 4} . N _4-2x ):Eu (0<X≦2) represents the phosphor of the composition, from the viewpoint of solving the new problem of maintaining light-emitting characteristics and improving durability, made intensive research, and even completed the present invention. [Means of Solving Problems]

According to the present invention, a phosphor particle can be provided, which is a phosphor having a composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ):Eu(0<X≦2) The crystalline phase of the bulk acts as a core, and the surface of the core is covered by a layer having polysiloxane bonds.

Further, according to the present invention, a light-emitting device including the above-described phosphor particles and a light-emitting light source can be provided.

Furthermore, according to the present invention, an image display device using the above-described light-emitting device can be provided.

In addition, according to the present invention, there can be provided a method for producing phosphor particles having the ability to represent Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ):Eu(0<X≦2) A step of forming a layer having a polysiloxane bond on the surface of the crystalline phase of the composed phosphor as a core. [Effect of invention]

According to the present invention, it is possible to provide a technique for phosphor particles having improved durability while maintaining light-emitting properties.

Hereinafter, embodiments of the present invention will be described in detail. In addition, in this specification, the description of "a to b" in the description of the numerical range means that a or more and b or less, unless otherwise specified.

In addition, the drawings are for illustrative purposes only. The shapes and size ratios of the components shown in the illustrations do not necessarily correspond to real objects.

<1. Phosphor particles> The phosphor particles of the present embodiment are represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ):Eu (0<X≦2) The crystalline phase of the composed phosphor serves as a core, and the surface of the core is covered by a layer having polysiloxane bonds. Thereby, durability, such as moisture resistance and water resistance, can be improved while maintaining light emission characteristics.

In addition, in the phosphor particle of the present embodiment, the coating of the surface by the layer having a polysiloxane bond is not limited to a continuous state, and a part may be a discontinuous state. In other words, a layer having a polysiloxane bond (also referred to as a coating layer) may be formed so as to cover the entire surface of the core, and at least a part of the coating layer may be formed in an island shape on the surface of the core. In addition, the layer having a polysiloxane bond in this embodiment is a layer obtained by using an organosilicon compound. That is, an organosilicon compound, and then a compound containing a polysiloxane bond is formed. In addition, the coating layer may be a continuous band in which the entirety is composed of fine particles of a compound having a polysiloxane bond, or a portion of which is a continuous band of fine particles of a compound having a polysiloxane bond. For example, the coating layer may be formed in an area of 10 to 90% of the entire surface of the core. In addition, when the coating layer is a particle of a compound having a polysiloxane bond, the particle size (D50) thereof is not particularly limited, but may be, for example, 1 to 30% of the particle size (D50) of the phosphor particles.

In the phosphor particles of the present embodiment, the wavelength of the emission peak is preferably 550 to 600 nm, and the full width at half maximum is 70 nm or less. Thereby, a narrow-band yellow phosphor with high brightness can be obtained.

The particle size (D10) of the phosphor particles of the present embodiment is preferably 1-50 μm, more preferably 5-40 μm, and more preferably 10-30 μm. The particle size (D50) of the phosphor particles of this embodiment is preferably 1-100 μm, more preferably 10-90 μm, more preferably 30-80 μm, and more preferably 40-70 μm. The particle size (D90) of the phosphor particles of the present embodiment is preferably 30-200 μm, more preferably 80-180 μm, and more preferably 100-150 μm. In addition, in this embodiment, for example, the particle diameter (D50) means the particle diameter equivalent to 50% of the integrated fraction of the volume based on the laser diffraction scattering method.

The content (mass %) of Si atoms in the phosphor particles of the present embodiment is preferably 0 to 4 mass %, more preferably 0.05 to 2 mass %, and more preferably 0.1 to 1.5 mass %. In addition, the content (mass %) of Si atoms can be adjusted by adjusting the amount of the organosilicon compound at the time of feeding, and by adjusting the temperature, time, or the type of solvent at the time of coating treatment in the method for producing phosphor particles. regulation.

In addition, the content (mass %) of Si atoms can be measured by preparing a test solution in which the phosphor particles are completely dissolved in an alkaline solvent (mixture of Na ₂ CO ₃ , K ₂ CO ₃ and H ₃ BO ₃ ). , and carried out by ICP (high frequency induction coupled plasma) luminescence analysis method.

The phosphor particles of the present embodiment preferably satisfy the following conditions. Thereby, the durability of the phosphor particles can be improved. Condition: The external quantum particle efficiency of the phosphor particles after being stored in an environment with a temperature of 50°C and a relative humidity of 80% for 7 hours is 30 relative to the external quantum particle efficiency of the phosphor particles before storage in this environment. %above.

Hereinafter, the core and the coating layer constituting the phosphor particles of the present embodiment will be described.

[Core] In the phosphor particles of the present embodiment, the core means a composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ):Eu(0<X≦2) It is composed of the crystalline phase of the phosphor. This phosphor is an Eu-activated phosphor obtained by substituting at least a part of Sr atoms with Eu atoms as an activating substance, and the phosphor of the crystal phase disclosed in Japanese Patent Application No. 2019-118166 of the applicant of the present application can be used.

In addition, the inventors of the present application have made intensive studies to synthesize a substance represented by a composition formula of SrLi ₃ AlO ₄ from raw material substances each containing Sr atom, Li atom, Al atom and O atom. As a result, it was found that the synthetic substance was not a mixture, and by analyzing the crystal structure, it was determined that it was a single compound with SrLi ₃ AlO ₄ as a unit and having a crystal structure not reported before the present invention. In addition, it was confirmed that not only the SrLi ₃ AlO ₄ crystal but also some or all of its atoms were substituted with other specific atoms, and the same crystal structure as that of the SrLi ₃ AlO ₄ crystal was maintained. In addition, it was confirmed that one of these series of substances has a composition represented by Sr(Li _1+x , Al _3-x )(O _2x N _4-2x ) (0<X≦2).

Furthermore, it was confirmed that at least a part of the Sr atoms of the crystal having the composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ) (0<X≦2) was substituted with Eu atoms, even if Regarding the crystal with the general formula: Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ): Eu(0<X≦2), the crystal will also maintain the same composition as Sr(Li _{1+ x} , Al _3-x )(O _2x N _4-2x )(0<X≦2) has the same crystal structure as the crystals of the composition, and can emit fluorescent light.

In Table 1, the results of the X-ray crystal structure analysis of the SrLi ₃ AlO ₄ crystal are shown. The preparation method of the SrLi ₃ AlO ₄ crystal will be described later.

[Table 1]

In Table 1, the lattice constants a, b, and c represent the lengths of the axes of the unit cells of the SrLi ₃ AlO ₄ crystal, and α, β, and γ represent the angles between the axes of the unit cells. In addition, the atomic coordinates x, y, and z in Table 1 represent the position of each atom in the unit cell as a value from 0 to 1 in the unit cell. In this crystal, an analysis result was obtained indicating that each atom of Sr atom, Li atom, Al atom, and O atom exists, and the Sr atom has two identical sites (Sr(1) to Sr(2)). In addition, an analysis result was obtained indicating that Li atoms and Al atoms exist, and that there are seven types of the same lattice sites (Li, Al(1) to Li, Al(7)). An analysis result was obtained indicating that Li atoms exist and that there is one site of the same type (Li(8)). Furthermore, an analysis result indicating that there are 8 identical lattice sites of O atoms was obtained.

Fig. 1 shows the crystal structure of the SrLi ₃ AlO ₄ crystal. In Figure 1, 1 is the O atom located at the vertex of the tetrahedron. The 2 series are Sr atoms located between the tetrahedra. The center of the 3 series is the AlO ₄ tetrahedron of the Al atom. The center of the 4 series is the LiO ₄ tetrahedron of the Li atom. That is, the SrLi ₃ AlO ₄ crystal system belongs to the triclinic crystal system, and belongs to the P-1 space group (space group No. 2 of International Tables for Crystallography). In addition, in this crystal, Eu atoms, which are so-called active atoms responsible for light emission, are incorporated into the crystal by substituting a part of Sr atoms.

The above results are not known technical information until the phosphor of the present invention is discovered, that is, the composition formula is Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ) (0<X≦ 2) A novel phosphor of the present embodiment in which at least a part of Sr atoms of the indicated crystal (phosphor precursor crystal) is substituted with Eu atoms.

In addition, a crystal having a composition represented by the composition formula Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ) (0<X≦2) is a part of the atoms of the SrLi ₃ AlO ₄ crystal or The crystals obtained by substituting all other atoms, or by further substituting Eu atoms as active atoms as described later, have different lattice constants from those of the SrLi ₃ AlO ₄ crystals shown in Table 1. However, in such a crystal, the basic crystal structure, the lattice positions occupied by atoms, and the atomic positions assigned depending on their coordinates do not change so much that the chemical bonds between the skeleton atoms are severed. The crystalline structure did not change.

That is, the above-mentioned "not only the above _- mentioned _SrLi3AlO4 crystal, but even if some or all of its atoms are substituted with other specific atoms, can still maintain the same crystal structure as that of the _SrLi3AlO4 crystal" means: for the composition _formula , it has The crystal with the composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x )(0<X≦2) is determined by the result of X-ray diffraction or neutron ray diffraction, with P The lattice constant obtained by Rietveld analysis and the atomic coordinate calculation for the space group of -1 are the lengths of the chemical bonds between Al atom-O atoms and between Li atoms and O atoms (close to the length of the chemical bonds between atoms) Compared with the chemical bond length calculated from the lattice constant and atomic coordinates of the SrLi ₃ AlO ₄ crystal shown in Table 1 above, it is within ±5%. At this time, it has been confirmed experimentally that when the change in the length of the chemical bond exceeds ±5%, the chemical bond is cut and another crystal is formed.

In the crystal having the composition represented by Sr(Li _1+x , Al _3-x )(O _2x N _4-2x ) (0<X≦2) of the present embodiment, for example, SrLi ₃ AlO ₄ shown in FIG. 1 In the crystal, the atoms represented by the symbol M can enter the lattice sites where the Sr atom enters; the atoms represented by the symbols L and A can enter the lattice sites where the Li atom and the Al atom respectively enter; the atoms represented by the symbol X can enter the lattice sites. Enter the lattice site where the O atom enters. According to this regularity, the crystal structure of the SrLi ₃ AlO ₄ crystal can be maintained, and the ratio of the number of atoms of M is 1, the sum of L and A is 4, and the sum of X is 4. In addition, Eu atoms can enter sites where Sr atoms enter. However, it is desirable that the sum of the positive charges shown by the atoms represented by M, L, and A and the Eu atoms and the sum of the negative charges shown by the atoms represented by X cancel each other out to maintain the electrical neutrality of the entire crystal.

FIG. 2 shows the peak pattern of powder X-ray diffraction using CuKα rays calculated from the crystal structure of the SrLi ₃ AlO ₄ crystal based on the numerical values shown in Table 1. FIG.

In addition, as a simple method for determining whether or not a crystal whose crystal structure is unknown has the same crystal structure as the above-mentioned SrLi ₃ AlO ₄ crystal, the following method is preferably used. That is, for a crystal whose crystal structure to be determined is unknown, the measured X-ray diffraction peak position (2θ) and the diffraction peak position shown in FIG. 2 are consistent with respect to the main peak. , the crystal structure of the two is the same, that is, it is a method for determining that the crystal structure of the crystal structure of the unknown crystal is the same as the crystal structure of the SrLi ₃ AlO ₄ crystal. The main peak portion may be determined by approximately 10 peak portions with strong diffraction intensity. In the present embodiment, this determination method is used in the examples.

As described above, the phosphor system of the present embodiment has at least the phosphor precursor crystal having the composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ) (0<X≦2) A phosphor obtained by substituting a part of M with Eu atoms, L is a part or all of Li atoms, A is a part or all of one or more atoms selected from Al atoms, Ga atoms and Si atoms, X It is an atom selected from one type or two types of O atom and N atom (however, X is only N atom excluding).

Here, in the production of a conventional phosphor, if a nitride, which is a raw material material containing N atoms, is used, a phosphor containing a small amount of O atoms derived from the raw material material can be produced. However, in this embodiment, as will be described later, a phosphor can be produced using an oxide which is a raw material material containing O atoms. The raw material used in this production method is not limited to oxides, but may also contain nitrides, not only nitrides. Therefore, X in the phosphor precursor crystal having the composition represented by Sr(Li _1+x , Al _3-x )(O _2x N _4-2x ) (0<X≦2) is not substituted with all N atoms.

In addition, in the phosphor of the present embodiment, the phosphor precursor crystal may be a crystal belonging to the triclinic system and having space group P-1 symmetry.

In addition, the phosphor of the present embodiment is preferably represented by the composition formula Sre Li _f Al _g O _h1 N _h2 Eu _i , and the composition ratios _e , f, g, h1, h2 and i satisfy the relational expressions shown below. e+f+g+h1+h2+i=9, 0＜e＜1.3, 0.7≦f≦3.3, 0.7≦g≦3.3, 3.7≦h1+h2≦4.3 (but h1＞0) 0＜i＜1.3 , and 0.7≦e+i≦1.3 It is considered that by having such a composition ratio, the phosphor precursor crystals are stably generated, and a phosphor having a higher luminous intensity can be obtained.

The above-mentioned composition ratio e is a parameter representing the composition ratio of Sr atoms, and if the composition ratio e is less than 1.3, the crystal structure becomes stable and the decrease in emission intensity can be suppressed. The above-mentioned composition ratio f is a parameter representing the composition ratio of Li atoms, and when the composition ratio f is 0.7 or more and 3.3 or less, the crystal structure is stabilized and the reduction in emission intensity can be suppressed. The above-mentioned composition ratio g is a parameter representing the composition ratio of Al atoms, and when it is 0.7 or more and 3.3 or less, the crystal structure is stabilized, and the reduction in emission intensity can be suppressed. The above-mentioned composition ratios h1 and h2 are parameters representing the composition ratios of O atoms and N atoms, respectively. If h1+h2 is 3.7 or more and 4.3 or less (however, h1>0), the crystal structure of the phosphor is stable and light emission can be suppressed. Decreased strength. The above-mentioned composition ratio i is a parameter representing the composition ratio of Eu atoms, and when i exceeds 0, the decrease in luminance due to the shortage of activated atoms can be suppressed. In addition, if i is less than 1.3, it is sufficient to maintain the structure of the phosphor precursor crystal. When i is 1.3 or more, the structure of the phosphor matrix crystal may become unstable. In addition, when i is less than 1.3, the reduction of the emission intensity due to the concentration extinction phenomenon caused by the interaction between the activated atoms can be suppressed, which is preferable.

In addition, it is considered that the above-mentioned composition ratios f and g are 7/40≦g/(f+g)＜30/40 The crystal structure of the fluorescent system is stable, especially the luminous intensity is high, which is ideal.

In addition, it is considered that the above-mentioned composition ratios h1 and h2 are 0<h1/(h1+h2)≦1, the crystal structure of the fluorescent system is more stable and the luminous intensity is high, which is preferable.

In addition, the phosphor of the present embodiment can emit fluorescence including a light emission peak in the wavelength range of 430 to 670 nm when irradiated with light including a light intensity peak in the wavelength range of 250 to 500 nm, for example.

In particular, when the above-mentioned light including an emission peak in the wavelength range of 250 to 500 nm is irradiated, fluorescence including an emission peak in the wavelength range of 560 to 580 nm can be emitted.

The phosphor of the present embodiment is a phosphor in which the above-mentioned phosphor precursor crystal is substituted with Eu atoms as active atoms. Phosphors containing Eu atoms as activated atoms are phosphors with high luminescence intensity. With a specific composition, blue to red fluorescence including emission peaks in the wavelength range of 430 to 670 nm can be obtained. phosphor.

In particular, the phosphor of this embodiment can also be represented by the composition formula Sr _1-r Li _3-q Al _1+q O _4-2q N _2q Eu _r , and the parameters q and r are 0≦q< 2. and 0<r<1 phosphors. The phosphor represented by the above composition formula is in the state of maintaining a stable crystal structure, by appropriately adjusting the values of the parameters of q and r, so that the ratio of Eu atom/Sr atom, Li atom/Al atom ratio, By changing the N atom/O atom ratio, the excitation peak wavelength and the emission peak wavelength of the phosphor can be continuously changed.

By changing the wavelength of the light emission peak of the phosphor, the color of light emitted when irradiated with excitation light, the value of (x, y) on the CIE1931 chromaticity coordinate can be, for example, 0≦x≦0.8, 0≦y≦ 0.9 range. Since such a phosphor can emit blue to red light, it is suitable to be used as a phosphor for white LEDs, for example.

In addition, the phosphor of the present embodiment is, for example, a phosphor that emits light by absorbing the energy of vacuum ultraviolet rays, ultraviolet rays, visible light, or radiation having a wavelength of 100 to 500 nm in the excitation source. Examples of radiation include X-rays, gamma rays, alpha rays, beta rays, electron rays, and neutron rays, and are not particularly limited. By using these excitation sources, the phosphor of the present embodiment can be efficiently made to emit light.

In addition, when the wavelength of the excitation light is 380 nm to 450 nm, the wavelength of the emission peak should be controlled to be 550 to 650 nm, preferably 550 to 630 nm, more preferably 550 to 590 nm, and the above parameters q and r should satisfy q=0 , and 0<r<0.05.

The phosphor of the present embodiment is preferably the particle of the single crystal of the phosphor of the present embodiment, or the aggregate obtained by agglomerating the particles of the single crystal of the phosphor of the present embodiment, or a mixture thereof. The phosphor of this embodiment is desirably as high in purity as possible. Substances other than the phosphor, such as impurities other than the phosphor that are inevitably contained, may also be included as long as the light emission of the phosphor is not impaired. such substances.

For example, the impurity atoms of Fe atoms, Co atoms, and Ni atoms contained in the raw material and the calcination container may reduce the luminous intensity of the phosphor. In this case, by making the total amount of impurity atoms contained in the phosphor to be 500 ppm or less, the influence on the decrease in the luminous intensity of the phosphor can be reduced.

In addition, when the phosphor of the present embodiment is produced, a compound having a crystal phase other than the phosphor and an amorphous phase (also referred to as a sub-phase) may be simultaneously produced. The secondary phase does not necessarily have the same composition as the phosphor of this embodiment. The phosphor of the present embodiment preferably does not contain a secondary phase as much as possible, but it may also contain a secondary phase within the range that does not impair the light emission of the phosphor.

That is, as one aspect of the phosphor of the embodiment, it will have the above-mentioned composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ) (0<X≦2) A mixture of a compound in which the crystal is used as a phosphor parent crystal and substituted with an Eu atom (activated atom) as an ion, and a compound having a sub-equivalent different from the above-mentioned compound; the content of the former compound is relative to The total amount of the phosphor in this embodiment is 50% by mass or more.

The above state can also be used when only the simple substance of the crystal having the composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ) (0<X≦2) cannot obtain the desired properties Sample. The content of the phosphor precursor crystal having the composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x )(0<X≦2) can be adjusted according to the characteristics of the purpose, as long as it becomes 20% by mass or more, the luminous intensity of the phosphor will be sufficiently improved. From such a viewpoint, in the phosphor of the present embodiment, it is preferable to use 20% by mass or more as the above-mentioned compound. In the case of such a phosphor, by irradiating the excitation source, fluorescence having an emission peak at a wavelength in the range of 400 to 670 nm can be obtained.

In addition, the shape of the core of the present embodiment is not particularly limited. When phosphor particles are used as dispersed particles, for example, single crystal particles with an average particle diameter of 0.1 to 50 μm, or single crystal particles are preferred. Agglomerates formed by agglomeration (aggregation). The phosphor particles with the core controlled to the particle size in this range have high luminous efficiency and good operability when installed in LEDs. The above-mentioned average particle diameter is determined by JIS Z8825 (2013), and is the volume-based particle diameter calculated from the particle size distribution (cumulative distribution) measured by the particle size distribution measuring apparatus using the laser diffraction scattering method as the measurement principle. (D50). In addition, the core (phosphor) of this embodiment can be fired again and used in a non-particle form. In particular, a plate-shaped sintered body containing a phosphor is also generally referred to as a phosphor plate, and can be suitably used, for example, as a light-emitting member of a light-emitting element.

[Coating layer (layer with polysiloxane bond)] The coating layer of the present embodiment is a layer that coats at least a part of the core. The coating layer is not particularly limited, and can be appropriately selected according to the purpose, but it is preferable to use an organosilicon compound from the viewpoint of effectively imparting high durability while maintaining the fluorescent characteristics. By using an organosilicon compound, hydrolysis and dehydration condensation reactions occur due to heat treatment or the like, so that a coating layer can be formed simultaneously with the formation of polysiloxane bonds. In addition, as the organosilicon compound, an organosilicon compound having a Si—O bond is preferably used. The above-mentioned organosilicon compound, for example, can be selected from the group consisting of tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), methyltriethoxysilane (MeTEOS), and phenyltriethoxysilane (PhTEOS). One or more of the group. Among them, tetraethoxysilane (TEOS) is more suitable from the viewpoint of stably forming the coating layer.

In addition, the average thickness of the coating layer of the present embodiment is not particularly limited, for example, it is preferably 1-200 nm, more preferably 3-180 nm, more preferably 5-100 nm, and even more preferably 10-50 nm. As a method for measuring the average thickness, for example, the cross section of the phosphor particle of the present embodiment is observed with a scanning or transmission electron microscope, and the thickness of the coating layer measured at arbitrary 5 to 20 positions can be calculated. way out. In addition, other methods for measuring the average thickness can be exemplified by assuming that the coating layer uniformly coats the surface of the core, and analyzing the value of Si obtained by elemental analysis using ICP emission spectrometry, the specific surface area of the phosphor particles, the coating The method of calculating the density of the layer to obtain the average thickness, etc. Among them, from the viewpoint of comparatively simple and stable measurement, the method calculated from the Si analysis value obtained by elemental analysis using ICP emission spectrometry and the specific surface area of the phosphor particles is preferable. .

The method of forming the coating layer of the present embodiment includes, for example, the coating layer forming step in the method for producing the phosphor particles described later.

<2. Manufacturing method of phosphor particles> An example of the manufacturing method of the phosphor particle of this embodiment is demonstrated. The phosphor particles of this embodiment at least include: a preparation step (step 1) of preparing a phosphor serving as a core; and a coating layer forming step (step 2) of forming a coating layer on the surface of the core. Hereinafter, each step will be described in detail.

[Step 1: Preparation steps] The procedure for preparing the phosphor as the core will be explained. First, a starting material containing Sr atoms, a starting material containing Li atoms, a starting material containing Al atoms, a starting material containing O atoms, a starting material containing N atoms, and a starting material containing Eu atoms are mixed to obtain Raw material mixture. In addition, when the raw material is a compound, one compound may contain many atoms among Sr atoms, Li atoms, Al atoms, O atoms, N atoms, and Eu atoms, and the raw material may be a single substance, which means that it can be A substance made up of individual atoms.

The raw material containing Sr atoms is a simple substance or a mixture of two or more kinds selected from metals containing Sr atoms, oxides, carbonates, hydroxides, nitrogen oxides, nitrides, hydrides, fluorides and chlorides , in particular, oxides are preferably used.

The raw material containing Li atoms is a simple substance or a mixture of two or more kinds selected from metals containing Li atoms, oxides, carbonates, hydroxides, nitrogen oxides, nitrides, hydrides, fluorides and chlorides , in particular, oxides are preferably used.

The raw material containing Al atoms is a simple substance or a mixture of two or more kinds selected from metals containing Al atoms, oxides, carbonates, hydroxides, nitrogen oxides, nitrides, hydrides, fluorides and chlorides , in particular, oxides are preferably used.

The raw material containing Eu atoms is a single substance or a mixture of two or more kinds selected from alloys containing Eu atoms, oxides, nitrides, fluorides and chlorides, and specifically, europium oxide is preferably used. Each raw material is preferably in powder form.

For example, when producing SrLi ₃ AlO ₄ phosphors (crystals) activated with Eu atoms, oxides, nitrides, or fluorides containing Eu atoms, and oxides, nitrides, or fluorides containing Sr atoms are preferably used Compounds, oxides, nitrides, or fluorides containing Li atoms, and oxides, nitrides, or fluorides containing Al atoms are used to prepare a raw material mixture. In addition, composite metals, oxides, carbonates, hydroxides, nitrogen oxides, oxides, carbonates, hydroxides, nitrogen oxides, Nitride, hydride, fluoride, or chloride or the like is used as the raw material. In particular, oxides containing Eu atoms (europium oxide), oxides containing Sr atoms (strontium oxide), oxides containing Li atoms (lithium oxide), and oxides containing Li atoms and Al atoms (lithium oxide) are preferably used aluminum).

In the method for producing a phosphor according to the present embodiment, in the calcination for synthesizing the phosphor, a compound containing atoms other than atoms constituting the phosphor may be formed into a liquid phase at a temperature lower than or equal to the calcination temperature. , added to the raw material and calcined. The compound that generates the liquid phase in this way acts as a flux, and plays a role in promoting the synthesis reaction of the phosphor and the growth of crystal grains. Therefore, stable crystals can be obtained and the luminous intensity of the phosphor can be improved.

Among the compounds that generate a liquid phase at a temperature below the calcination temperature, there are fluorides, chlorides, iodides, bromides and One type or a mixture of two or more types of phosphates. They may also be compounds containing atoms other than those constituting the phosphor. In addition, since these compounds differ from each other in melting|fusing point, it can be used separately depending on a synthesis temperature. These compounds that generate a liquid phase are also included in the raw material for convenience in this embodiment.

When the phosphor is formed into particles or aggregates, each raw material is preferably particles. In addition, since the synthesis reaction of the phosphor occurs from the contact portion between the particles of the raw material as a starting point, if the average particle size of the particles of the raw material is set to 500 μm or less, the contact portion of the particles increases and The reactivity is improved, so it is ideal.

(mixed method) In the method for producing the phosphor of the present embodiment, the method of mixing the respective raw materials to obtain a raw material mixture is not particularly limited, and a known mixing method can be used. That is, in addition to the method of mixing each raw material in a dry manner, the mixing may be performed by wet mixing in an inert solvent that does not substantially react with each raw material, followed by a method of removing the solvent, or the like. . In addition, as the mixing device, a V-type mixer, a rocking mixer, a ball mill, a vibrating mill and the like are preferably used.

(calcination vessel) In the calcination of the raw material mixture, as the calcination container for holding the raw material mixture, a container made of various heat-resistant materials can be used. Containers, carbon containers such as carbon sintered bodies, containers made of metals such as molybdenum, tungsten, or tantalum, etc.

(calcination temperature) In the method for producing the phosphor of the present embodiment, the firing temperature of the raw material mixture can be appropriately set, for example, 780 to 1500°C. By setting the firing temperature to 780° C. or higher, the crystal growth of the phosphor is facilitated, and sufficient fluorescent properties can be obtained. In addition, by setting the firing temperature to 1500° C. or lower, it is possible to suppress the decomposition of the phosphor and suppress the degradation of the fluorescent properties. In addition, the calcination time varies depending on the calcination temperature, but is usually about 1 to 10 hours. The modes of heating, temperature maintenance, and cooling with time during calcination are not particularly limited, and raw materials may be added as necessary during calcination.

(Calcination Environment) The calcination step is preferably carried out in a reducing calcination environment in which at least a part of Eu ³⁺ in the raw material mixture can be reduced to Eu ²⁺ . Examples of the calcination environment include neutral gases such as NH ₃ and N ₂ , and reducing gases such as H ₂ and CH ₄ . These can be used alone or in combination of two or more. Among them, from the viewpoint of improving the luminous intensity of the phosphor, NH ₃ , N ₂ or H ₂ can be used in the calcination environment, and NH ₃ or N ₂ is preferably used. The calcination environment, for example, may be composed of NH ₃ or N ₂ as a main component. The purity of _NH3 or _N2 , at 200°C, is, for example, 98% or more by volume, preferably 99% or more by volume. In addition, for the furnace materials such as heat insulating materials and heaters, electric furnaces made of carbon and graphite resistance heating method, all-metal furnaces made of molybdenum or tungsten, and furnace core tubes made of alumina or quartz can be used. A tubular furnace heated by a heater, a furnace provided with corrosion resistance. Appropriate gas types can be used according to the furnace material.

(calcination pressure) The pressure during calcination is preferably as high as possible in order to suppress thermal decomposition of the raw material mixture and the phosphor, that is, the product. The specific pressure during calcination is preferably 0.1 MPa (atmospheric pressure) or more.

(Number of calcinations) The number of times of the above-mentioned calcination steps may be one time or multiple times. In addition, the number of calcination steps is controlled by the calcination temperature and calcination pressure. Under the condition of maintaining the regulated calcination temperature and calcination pressure, after calcining the raw material mixture, as the control of the calcination pressure is released, the fluorescence obtained by calcination The body (sintered body) was cooled to room temperature, which was defined as 1 cycle, and the number of repetitions of this cycle was called the number of calcination steps.

(annealing treatment after calcination) The phosphor obtained by calcination, the phosphor particles after pulverization, and the phosphor particles after further particle size adjustment can also be heat-treated at a temperature of 600-1300°C (also called annealing treatment). . By this operation, the defects contained in the phosphor and the damage due to pulverization may be recovered. Defects and damages may cause a decrease in the luminous intensity, and the luminous intensity may be recovered by the above-mentioned heat treatment.

In addition, the phosphor after calcination and after the above-mentioned annealing treatment may be washed with a solvent, or an acidic or alkaline solution. This operation can also reduce the content and subphase of the compound that generates a liquid phase at a temperature lower than the calcination temperature. As a result, the luminous intensity of the phosphor increases.

[Step 2: Coating Layer Forming Step] Next, a coating layer is formed on the surface of the obtained core. For example, it is preferable to form a layer having a polysiloxane bond on the surface of the crystal phase of the phosphor by contacting the phosphor obtained in the step 1 with an organosilicon compound to be described later, and performing heat treatment. A detailed description will be given below. (Preparation of Slurry) First, the obtained core (crystalline phase) is dispersed in a dispersion medium to prepare a slurry. The dispersion medium can be used without particular limitation as long as the core does not dissolve but the organosilicon compound dissolves. As the dispersion medium, for example, known organic solvents can be exemplified, and ethanol, isopropanol, and the like can be used. In addition, NH ₄ OH can also be used for the hydrolysis described later. Moreover, in order to disperse|distribute uniformly, a well-known method may be used for stirring, and this stirring may be performed at room temperature.

(Addition of organosilicon compound) An organosilicon compound etc. are added to the obtained slurry, and it is made to disperse|distribute. Regarding the amount of the organosilicon compound to be added, the content of Si atoms in the organosilicon compound is preferably adjusted so as to be 0.001 to 10 parts by mass relative to 100 parts by mass of the core. A known method can be used for the addition method of an organosilicon compound, and it can also be performed by dripping. In addition, when APTES and TEOS are used as organosilicon compounds, APTES and TEOS can be hydrolyzed and gelled by a known method using a base such as NH ₄ OH. The stirring time is not particularly limited, and may be, for example, 15 minutes to 2 hours.

(Post-treatment) Then, the dispersion liquid is filtered and heated to obtain phosphor particles in which the coating layer is formed on the surface of the core. The filtration and heating methods are not particularly limited, and known methods can be used. The heating conditions can be set to, for example, 100 to 500° C. for 1 to 15 hours, or 1 to 5 hours in the atmosphere. Thereby, a layer having a polysiloxane bond can be stably formed on the core surface. In addition, from the viewpoint of suppressing the oxidation of Eu ²⁺ , etc., it is also possible to set it in a nitrogen atmosphere.

By setting in this way, phosphor particles in which the surface of the core is covered with the coating layer can be obtained.

[performance] Accordingly, the phosphor particles of the present embodiment can have a wide excitation range of radiation and ultraviolet light to visible light, and can emit blue to red light. In particular, the phosphor particles having a core with a specific composition can emit blue to red light in the range of 450-650 nm, and can adjust the wavelength of the luminescence peak and the full width at half maximum. In addition, the phosphor particles of the present embodiment can improve durability while maintaining such light-emitting properties. In addition, the phosphor particles of the present embodiment are useful as a material constituting a phosphor plate and a light-emitting element using the phosphor plate. In addition, lighting equipment and image display devices using the above-mentioned light-emitting elements also exhibit high color reproducibility. In addition, the phosphor particles of this embodiment are also suitable for use in pigments and ultraviolet absorbers. The phosphor particles of the present embodiment can be used not only alone. For example, by mixing each material containing the phosphor particles of the present embodiment with a resin, etc. to prepare a composition, and then molding the composition, it is possible to provide a fluorescent molded article, a fluorescent sheet, or a fluorescent film. the shaped body. In addition, the phosphor particles of the present embodiment also have the advantages that they are not easily deteriorated even when exposed to high temperatures, have excellent heat resistance, and are also excellent in long-term stability in oxidative environments and moisture environments, and can provide excellent durability. product.

<3. Light-emitting element> The phosphor particles of this embodiment can be used in various applications. A light-emitting element containing the phosphor particles of the present embodiment is also one aspect of the present invention. Regarding the above-mentioned light-emitting element, the phosphor particles of the present embodiment may be used as they are in the form of particles, or may be calcined again to be in the form of agglomerates. In some cases, a sintered body obtained by firing the phosphor particles again, particularly into a flat plate shape, is also referred to as a phosphor plate. In addition, the light-emitting element referred to here is generally constituted by including a phosphor and an excitation source of the phosphor.

When the phosphor particles of this embodiment are used to form light-emitting elements generally called light-emitting diodes (also called LEDs), for example, it is generally appropriate to disperse the phosphor particles of this embodiment in Formed body or sintered body of a composition containing phosphor particles obtained from resins and glass (these are collectively referred to as solid media), and the form in which the phosphor particles are irradiated with excitation light from an excitation source . In this case, phosphors other than the phosphor particles of the present embodiment may be contained in the composition containing phosphor particles.

The resin used as the solid medium of the above-mentioned composition containing phosphor particles can be used, as long as it is in a liquid state before molding or when the phosphor particles are dispersed, and does not generate phosphor particles or luminescence which is not the case with the present embodiment. If it is an undesired reaction or the like for the element, any resin can be selected according to the purpose or the like. Examples of resins include addition reaction type polysiloxane resins, condensation reaction type polysiloxane resins, modified polysiloxane resins, epoxy resins, polyethylene-based resins, polyethylene-based resins, polypropylene-based resins, polyester resin, etc. One type of these resins may be used alone, or two or more types may be used in combination in arbitrary combinations and ratios. When the said resin is a thermosetting resin, by making it harden, the molded object (hardened body) of the fluorescent substance particle containing composition which disperse|distributed the fluorescent substance particle of this embodiment can be obtained.

The usage ratio of the above-mentioned solid medium is not particularly limited, and can be appropriately adjusted according to the application, etc. Generally speaking, the mass ratio of the solid medium to the phosphor particles of this embodiment is usually 3 mass % or more, preferably 5 mass % % or more, and generally 30 mass % or less, preferably 15 mass % or less.

In addition, the phosphor-containing composition of the present embodiment may contain other components in addition to the phosphor particles and the solid medium of the present embodiment, depending on the application and the like. Other components include diffusing agents, thickeners, extenders, interference agents, and the like. Specifically, silicon oxide-based micropowders such as AEROSIL, alumina, and the like can be exemplified. Thereby, it becomes easy to obtain favorable diffusivity and viscosity.

In addition, phosphors other than the phosphor particles of the present embodiment can be selected from BAM phosphors, β-silicon aluminum oxynitride phosphors, α-silicon aluminum oxynitride phosphors, Sr ₂ Si ₅ N ₈ phosphor, (Sr,Ba) ₂ Si ₅ N ₈ phosphor, CaAlSiN ₃ phosphor, (Ca, Sr)AlSiN ₃ phosphor, KSF phosphor, YAG phosphor, and ( Ca, Sr, Ba) Si ₂ O ₂ N ₂ of one or more kinds of phosphors.

As for one of the embodiments of the light-emitting element, the composition containing the phosphor particles of this embodiment may further contain the emission peak wavelengths emitted by the light-emitting body or the excitation source in addition to the phosphor particles of the present embodiment. It is a blue phosphor for light of 420 to 500 nm. Such blue phosphors include, for example, AlN: (Eu, Si), BAM: Eu, SrSi ₉ Al ₁₉ ON ₃₁ : Eu, LaSi ₉ Al ₁₉ N ₃₂ : Eu, α-SiAl oxynitride: Ce , JEM: Ce and so on.

In addition, as for one of the embodiments of the light-emitting element, the composition containing the phosphor particles of the present embodiment may further contain, in addition to the phosphor particles of the present embodiment, a luminescence peak due to a light-emitting body or an excitation source A green phosphor for light with a wavelength of 500 to 550 nm. Such a green phosphor, for example, β-silicon aluminum oxynitride: Eu, (Ba, Sr, Ca, Mg) ₂ SiO ₄ : Eu, (Ca, Sr, Ba) Si ₂ O ₂ N ₂ : Eu Wait.

In addition, in one of the embodiments of the light-emitting element, the composition containing the phosphor particles of the present embodiment may further contain a luminescence peak due to the light-emitting body or the excitation source in addition to the phosphor particles of the present embodiment. A yellow phosphor for light with a wavelength of 550 to 600 nm. Such yellow phosphors include, for example, YAG: Ce, α-SiAl oxynitride: Eu, CaAlSiN ₃ : Ce, La ₃ Si ₆ N ₁₁ : Ce, and the like.

In addition, with regard to one of the embodiments of the light-emitting element, the composition containing the phosphor particles of the present embodiment may further contain, in addition to the phosphor particles of the present embodiment, light emitted by a light-emitting body or an excitation source. A red phosphor for light with a peak wavelength of 600 to 700 nm. Examples of such red phosphors include CaAlSiN ₃ :Eu, (Ca,Sr)AlSiN ₃ :Eu, Ca ₂ Si ₅ N ₈ :Eu, Sr ₂ Si ₅ N ₈ :Eu, KSF:Mn, and the like.

In the light-emitting element of the present embodiment, when the phosphor particles of the present embodiment are contained as the phosphor plate, the phosphor plate means that the phosphor of the present embodiment in the form of particles is formed into a desired shape, A sintered body obtained by heating and calcining. However, the phosphor plate of the present embodiment may contain phosphors other than the phosphor particles of the present embodiment, or other components. The other components referred to here include, for example, glass used as a medium, or a binder resin, a dispersant, and a sintering aid. The additives for the above-mentioned binder resin, dispersant, and sintering aid are not particularly limited, and generally known substances in the field that are decomposed and removed at the same time during heating and sintering can be suitably used.

The average particle size of the phosphor particles used in the production of the phosphor plate is not particularly limited. Since the addition amount of the binder resin for imparting formability will increase or decrease with the specific surface area of the phosphor particles, for example, it is preferable to 0.1 to 30 μm.

The above-mentioned phosphor plate can be produced, for example, by the following method. In the phosphor particles of this embodiment, additives such as binder resin, dispersant, and sintering aid are added, and a dispersion medium is added and wet-mixed to adjust the viscosity of the obtained slurry to form a sheet or disc. It is heated and calcined to decompose and remove the additive. Thereby, the phosphor sheet of this embodiment can be obtained. The heating and calcining temperature, time, and calcining environment may be appropriately changed to known conditions depending on the material to be used. In addition, a method of adding a glass powder having a lower melting point than the phosphor particles of the present embodiment, molding, and then firing to produce a phosphor plate is also effective.

The excitation source contained in the light-emitting element of the present embodiment can excite the phosphor particles of the present embodiment or other types of phosphors to emit light. The excitation source is, for example, a light source that emits excitation energy. The phosphor of this embodiment emits light even if it is irradiated with vacuum ultraviolet rays of 100-190 nm, ultraviolet rays of 190-380 nm, electron beams, etc., but as a suitable excitation source, for example, a blue semiconductor light-emitting element can be exemplified. The phosphor particles of this embodiment also emit light by the light from the excitation source, and thus can be suitably used in a light-emitting element. In addition, the light-emitting element of the present embodiment does not necessarily need to be a single element, and may be a one-piece element obtained by combining a plurality of light-emitting elements.

In one form of the light-emitting element of the present embodiment, the light-emitting body or excitation source emits ultraviolet light or visible light with a peak wavelength of 300-500 nm, preferably 300-470 nm, by emitting the phosphor particles of this embodiment. blue light to yellow-green light to red light (for example, 435 nm to 570 nm to 750 nm), mixed with light with a wavelength of 450 nm or more emitted by other phosphors of this embodiment to emit white light or light other than white light. light-emitting element.

In addition, the above-mentioned embodiment of the light-emitting element is an example, and in addition to the phosphor of the present embodiment, if a blue phosphor, a green phosphor, a yellow phosphor or a red phosphor is appropriately combined, it is possible to produce a The love of white light in the desired hue is self-evident.

In addition, in one of the embodiments of the light-emitting element, if an LED that emits light having a wavelength of 280 to 500 nm by a light-emitting body or an excitation source is used, the light-emitting efficiency is high, so that a high-efficiency light-emitting device can be formed. In addition, the light from the excitation source used is not particularly limited to monochromatic light, and may be polychromatic light.

In FIG. 3 , a light-emitting element (surface-mounted LED) using the phosphor particles of the present embodiment is schematically shown.

A surface-mounted white light-emitting diode lamp (11) is produced. Two lead wires (12, 13) are fixed on a white alumina ceramic substrate (19) with high visible light reflectivity. One end of the lead wires (12, 13) is located in the approximate center of the alumina ceramic substrate (19), and the other ends are exposed to the outside and become electrodes for soldering when mounted on the electrical substrate. A blue light-emitting diode element (14) with an emission peak wavelength of 450 nm is placed and fixed on one end of the lead (13) of one of the leads (12, 13) so as to become the center of the substrate. The lower electrode and the lead (13) of the blue light-emitting diode element (14) are electrically connected by a conductive paste, and the upper electrode and the other lead (12) are made of a bonding wire composed of a thin gold wire. wire) (15) is electrically connected.

The mixture of the first resin (16) and the phosphor particles (17) of the above-mentioned embodiment is arranged near the blue light-emitting diode element (14). The first resin (16) in which the phosphor particles (17) are dispersed is transparent and covers the entirety of the blue light-emitting diode element (14). In addition, on the alumina ceramic substrate (19), a wall surface member (20) having a shape of opening a hole in the center portion is fixed. The central part of the wall member (20) becomes a hole for accommodating the blue light-emitting diode element (14) and the first resin (16) in which the phosphor particles (17) are dispersed, and the part facing the center becomes an inclined surface . The inclined surface is a reflective surface used to extract light upward. The inclined surface can be flat or curved. In this case, the curved surface can be determined in consideration of the reflection direction of the light. Further, at least the surface constituting the reflective surface is a surface with a high visible light reflectance of white or metallic luster. In the light-emitting element, the wall member (20) is made of white polysiloxane. The hole in the central part of the wall member (20) can also be formed as a concave part in terms of the final shape when used as a wafer-type light-emitting diode lamp. (14) and the first resin (16) in which the phosphor particles (17) are dispersed are all sealed and filled with a transparent second resin (18). In this light-emitting element, the same epoxy resin can be used for the first resin (16) and the second resin (18). The light-emitting element emits white light.

<4. Light-emitting device> In addition, a light-emitting device having the phosphor particles of the present embodiment and a light-emitting light source is also one aspect of the present invention. Specific examples of the light-emitting device include lighting equipment, backlights for liquid crystal panels, various display devices, and the like. As the light-emitting light source, a known light-emitting element can be used. For example, a light-emitting device that emits white light can be obtained by using a white LED, one of the light-emitting elements, as a light-emitting light source, in combination with the phosphor particles of the present embodiment.

<5. Image Display Device> In addition, an image display device having the light-emitting device of the above aspect is also one aspect of the present invention. Specific examples of the image display device include a fluorescent display tube (VFD), a field emission display (FED), a plasma display (PDP), a cathode ray tube (CRT), a liquid crystal display (LCD), and the like.

＜6. Pigment＞ The phosphor particles of the present embodiment can also be used as, for example, a constituent material of pigments by utilizing their functions. The phosphor particles of this embodiment have good color rendering of the white object color observed when irradiated with sunlight, fluorescent lamps, etc., and will not deteriorate over a long period of time, so the phosphor particles of this embodiment can be Suitable for use, for example, in inorganic pigments. Therefore, if the phosphor particles of this embodiment are added to paints, printing inks, painting utensils, glazes, and plastic products and used as pigments, good whiteness can be maintained for a long time.

<7. Ultraviolet absorber> The phosphor particles of the present embodiment are not only used alone, but can also be used as a constituent material of an ultraviolet absorber, for example, by utilizing their functions. That is, the ultraviolet absorber containing the phosphor particles of the present embodiment is kneaded into plastic products, paints, or coated on the surface of plastic products, so as to effectively protect them from being deteriorated by ultraviolet rays.

<8. Phosphor sheet> The phosphor particles of this embodiment, for example, are mixed with a resin to form a composition, and the phosphor molded article, phosphor film, and phosphor sheet obtained by molding the phosphor particles can also be used as examples of this embodiment. A suitable example of use of phosphor particles. For example, the phosphor sheet of the present embodiment referred to here refers to a sheet of the phosphor particles of the present embodiment in which the phosphor particles of the present embodiment are uniformly dispersed in a medium. material. The material of the medium is not particularly limited, and a material that has transparency and can maintain a sheet-like shape is suitable, for example, resin. Specific resins include polysiloxane resins, epoxy resins, polyarylate resins, PET-modified polyarylate resins, polycarbonate resins, cyclic olefins, polyethylene terephthalate resins, polymethyl methacrylates Methyl acrylate resin, polypropylene resin, modified acrylic resin, polystyrene resin and acrylic nitrile styrene copolymer resin, etc. In the phosphor sheet of the present embodiment, silicone resin and epoxy resin are preferably used in terms of transparency. In consideration of heat resistance, polysiloxane should be used.

In the phosphor sheet of this embodiment, additives may be added as required. For the additives, for example, a leveling agent during film formation, a dispersing agent that promotes the dispersion of phosphor particles, or an adhesive adjuvant such as a silane coupling agent as a modifier of the sheet surface can be added. In addition, inorganic particles such as silicone resin fine particles may be added to the phosphor sheet of the present embodiment as a sedimentation inhibitor of the phosphor particles.

The thickness of the phosphor sheet of the present embodiment is not particularly limited, and may be determined from the content of phosphor particles and desired optical properties. From the viewpoint of increasing the content of the phosphor particles and improving the handleability, optical properties, and heat resistance, the thickness is, for example, 10 to 3 mm, preferably 50 to 1 mm.

There is no restriction|limiting in particular in the manufacturing method of the fluorescent substance sheet of this embodiment, A well-known method can be used. In addition, the phosphor sheet of the present embodiment may be a single-layer sheet or a multi-layer sheet as long as it contains the phosphor of the present embodiment. In addition, the thickness of the whole phosphor sheet of this embodiment does not necessarily have to be uniform. The phosphor sheet of this embodiment may be provided with a base material layer on the surface or inside of one side or both sides. The material of the base material layer is also not particularly limited, and for example, known metals, films, glass, ceramics, paper, and the like can be used. In the specific substrate layer, metal plates or metal foils such as aluminum (including aluminum alloys), zinc, copper, iron, etc. can be used, such as cellulose acetate, polyethylene terephthalate (PET), polyethylene, Polyester, polyamide, polyimide, polyphenylene sulfide, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, polyarylamide (aramid) and other plastic films, through the above plastic layer Laminated paper, or coated paper with the above-mentioned plastic, paper laminated or evaporated by the above-mentioned metal, plastic film laminated or evaporated by the above-mentioned metal, etc. In addition, when a metal plate is used for the base material layer, the surface of the metal plate may be subjected to plating treatment such as chromium-based, nickel-based treatment, or ceramic treatment. In particular, the material of the substrate layer is preferably a soft and high-strength film. Therefore, the material of the base material layer is preferably a resin film, for example, a PET film, a polyimide film, etc. can be specifically mentioned.

As mentioned above, although embodiment of this invention was described, these are examples of this invention, and various structures other than the above may be employ|adopted. [Example]

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

(Raw Material) As the raw material of SrLi ₃ AlO ₄ , alumina (Al ₂ O ₃ , Tymicron, manufactured by Daming Chemical Industry Co., Ltd.) particles, strontium oxide (SrO, manufactured by High Purity Chemical Co., Ltd.) particles, lithium oxide were used (Li ₂ O, manufactured by High Purity Chemical Co., Ltd.) particles, lithium aluminate (LiAlO ₂ , manufactured by High Purity Chemical Co., Ltd.) particles, and europium oxide (Eu ₂ O ₃ , manufactured by Shin-Etsu Chemical Co., Ltd. with a purity of 99.9%) particles.

<Example 1> 1) Preparation of crystal phase According to the design composition of the crystal phase (the atomic ratio (design value) of Sr:Eu:Li:Al:O is 0.990:0.010:3.0:1.0:4.0), the particle-like The ratio of SrO: _Li2O :LiAlO2 _: Eu2O3 ₍ mass ratio) _of each raw material was 51.25:14.93:32.94:0.88 (mass ratio), and weighed in a glove box filled with dried _N2 gas . The weighed raw material was mixed for 10 minutes using a silicon nitride sintered pestle and mortar to obtain a raw material mixture. Then, a crucible made of alumina was filled with this raw material mixture.

The above-mentioned crucible filled with the raw material mixture was set in a tubular furnace. The calcination procedure of the raw material mixture is as follows. First, the calcination environment was temporarily reduced to 10Pa or less by a rotary pump, NH ₃ with a purity of 99.999% by volume was introduced to make the pressure in the furnace atmospheric pressure, and the flow rate of NH ₃ gas was adjusted to 2L/min. The temperature was raised to 800°C at a rate of 7°C per minute and maintained at this temperature for 4 hours. Then, the introduction of NH ₃ gas was released, and it was cooled to room temperature.

The calcined product was taken out from the crucible, pulverized using a pestle and mortar of the silicon nitride sintered body, and passed through a 75 μm mesh screen to obtain a particulate phosphor (ie, the core of the crystal phase of Example 1). After the particle size distribution was measured by laser diffraction method, the particle size D50 was 18 μm. After performing elemental analysis on the particulate phosphor by ICP emission spectrometry, the atomic ratio (analytical value) of Sr atom, Li atom, and Al atom was 1.0:3.0:1.0, and it was confirmed that the composition did not change before and after firing.

2) Covered 1.5 g of the obtained particulate phosphor (core) was added to a mixed solution of 20 mL of ethanol and 2.9 mL of 28% by mass ammonia to prepare a slurry. A mixed solution of 0.6 mL of tetraethoxysilane (manufactured by Kanto Chemical Co., Ltd.) and 6.2 mL of ethanol was added dropwise to the slurry, followed by stirring at room temperature for 1 hour. Then, after the stirring was stopped, the slurry was filtered, and the recovered product was dried at 100° C. for 12 hours to obtain phosphor particles in which the surface of the core was covered with a coating layer.

<Reference example> The crystal phase obtained in Example 1 was used as the phosphor particle of the reference example.

Using the obtained phosphor particles, the following measurements and evaluations were performed. The results are shown in Table 2.

(X-ray diffraction) With respect to the crystal phase (core) of Example 1, powder X-ray diffraction measurement using Cu Kα rays was performed. The X-ray diffraction pattern showed good agreement with the X-ray pattern calculated from the SrLi ₃ AlO ₄ crystal shown in FIG. 2 , and it was confirmed that the crystal had the same crystal structure as the SrLi ₃ AlO ₄ crystal. Therefore, it was confirmed that the crystal phase of Example 1 was an inorganic compound in which Eu atoms were substituted for the SrLi ₃ AlO ₄ crystal.

(Particle Size) For the phosphor particles obtained in Example 1, the particle diameters (D10, D50, D90) corresponding to cumulative 10, 50, and 90% in the volume-based integration fraction by the laser diffraction scattering method were measured. As a result, D10 was 18.4 μm, D50 was 69.4 μm, and D90 was 130.2 μm.

[durability, light emission characteristics] Each phosphor particle was stored in an environment with a temperature of 50° C. and a relative humidity of 80% for 7 hours, and a durability test was carried out. The external quantum efficiency of the phosphor particles before and after the durability test was measured by a multi-channel spectrometer (manufactured by Otsuka Electronics Co., Ltd., "MCPD-7000"), and calculated by the following procedure. Each phosphor particle is filled in the sample part so that the surface of the concave groove becomes smooth, and is installed at a predetermined position of the integrating sphere. An optical fiber was used to introduce monochromatic light having a wavelength of 455 nm from a light emitting light source (Xe lamp) into the integrating sphere. This monochromatic light is used as an excitation source, and the phosphor particles are irradiated, and the fluorescence spectrum thereof is measured. Based on the emission spectrum obtained by the measurement, the emission peak wavelength and the full width at half maximum were determined. A standard reflector (“Spectralon”, manufactured by Labsphere, Inc.) having a reflectance of 99% was attached to the sample portion, and the spectrum of excitation light having a wavelength of 455 nm was measured. At this time, the number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm. The sample portion was filled with each phosphor particle, and the number of excitation reflected light photons (Qref) and the number of fluorescence photons (Qem) were calculated from spectral data obtained by irradiating excitation light with a wavelength of 455 nm. The photon number system of excitation reflected light is calculated in the same wavelength range as the photon number of excitation light, and the photon number system of fluorescence is calculated in the range of 465-800 nm. External quantum efficiency=(Qem/Qex)×100

[Normalization of External Quantum Efficiency] The external quantum efficiency before the endurance test was set to 100%, and the external quantum efficiency (%) after the endurance test was calculated and normalized by using this as a benchmark. The results are shown in Table 2.

[Content (mass %) of Si atoms in phosphor particles] 100 mg of each phosphor particle was weighed into a platinum crucible, and 1 g of an alkaline flux (Na ₂ CO ₃ , K ₂ CO ₃ and H ₃ BO was added) The mixture of ₃ ) was heated at 900°C for 15 minutes for heating and melting. After standing to cool, 10 mL of hydrochloric acid was added, dissolved in a 100° C. water bath, and the volume was adjusted to 100 mL, and then diluted to 5 times with hydrochloric acid to obtain a test solution. With respect to this test solution, elemental analysis of Si atoms was carried out using an ICP emission spectrometer (manufactured by Agilent Technologies, "5110VDV"). As a result, Si atoms were not detected in the sample without coating (reference example). The content of Si atoms in the phosphor particles of Example 1 was 0.28 mass %.

[Average thickness of coating layer] For Example 1, the average thickness was calculated from the mass of Si atoms, the specific surface area of the phosphor particles, and the density of the coating layer, assuming that the coating layer was uniformly coated on the surface of the core. The specific surface area of the phosphor particles was measured by a gas adsorption method, and as a result, the specific surface area of the phosphor particles was 0.159 m ² /g. As described above, since the Si atom of the phosphor particles of Example 1 is 0.28 mass %, it can be calculated that there are 0.28×10 ^-2 g of Si atoms per 1 g of the phosphor particles. If the mass of SiO ₂ is converted from the atomic weight of Si (28.086) and the atomic weight of SiO ₂ (60.084), it becomes 5.99×10 ⁻³ g. If it is divided by the density of SiO ₂ (2.65g/cm ³ ), the volume of SiO ₂ per 1 g of the phosphor particles can be calculated to be 2.26×10 ^-9 m ³ , by dividing the volume by the The average thickness was obtained from the specific surface area of the phosphor particles. As a result, the average thickness of the phosphor particles of Example 1 was 14 nm.

[Table 2]

According to Table 2, it can be confirmed that the phosphor particles of Example 1 can maintain the external quantum better than the phosphor particles of the reference example when stored for 7 hours in an environment with a temperature of 50°C and a relative humidity of 80%. efficiency.

This patent application claims priority on the basis of Japanese Patent Application No. 2020-192433 filed on November 19, 2020, and the entire disclosure thereof is incorporated herein by reference.

1: Oxygen atom 2: Strontium atom 3: AlO ₄ tetrahedron (center Al atom) 4: LiO ₄ tetrahedron (center Li atom) 11: Surface mount type white light-emitting diode lamp 12, 13: Lead wire 14: Blue Light emitting diode element 15: Bonding wire 16: First resin 17: Phosphor particles 18: Second resin 19: Alumina ceramic substrate 20: Wall member

[ Fig. 1] Fig. 1 is a diagram showing the crystal structure of the SrLi ₃ AlO ₄ crystal. [ Fig. 2 ] A diagram showing powder X-ray diffraction using CuKα rays calculated from the crystal structure of the SrLi ₃ AlO ₄ crystal. [ Fig. 3] Fig. 3 is a schematic diagram of a surface-mounted LED element using the phosphor of the present embodiment.

1: Oxygen atom

2: Strontium Atom

3: AlO ₄ tetrahedron (central Al atom)

4: LiO ₄ tetrahedron (central Li atom)

Claims (13)

A phosphor particle having a crystal phase of a phosphor having a composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ):Eu(0<X≦2) as a core , the surface of the core is covered by a layer having polysiloxane bonds. The phosphor particle of claim 1, wherein the layer having a polysiloxane bond is formed by using an organosilicon compound. The phosphor particle of claim 2, wherein the organosilicon compound is selected from the group consisting of tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), methyltriethoxysilane (MeTEOS), and phenyl triethoxysilane One or more of the group consisting of ethoxysilanes (PhTEOS). The phosphor particle according to claim 1 or 2, wherein the wavelength of the emission peak is 550 to 600 nm, and the full width at half maximum is 70 nm or less. The phosphor particle of claim 1 or 2, wherein the layer having polysiloxane bonds has an average thickness of 1-200 nm. The phosphor particle according to claim 1 or 2, wherein the particle size (D50) of the phosphor particle is 1-100 μm. The phosphor particle of claim 1 or 2, wherein the external quantum particle efficiency of the phosphor particle after being stored in an environment with a temperature of 50° C. and a relative humidity of 80% for 7 hours is higher than that stored in the environment The external quantum particle efficiency of the phosphor particles was above 30%. A light-emitting device comprising the phosphor particles according to any one of claims 1 to 7, and a light-emitting light source. An image display device including the light-emitting device of claim 8. A method for producing phosphor particles, comprising: a phosphor having a composition represented by Sr(Li _1+x ,Al _3-x )(O _2x N _4-2x ):Eu(0<X≦2) The step of forming a layer having polysiloxane bonds on the surface of the crystalline phase as a core. The method for producing phosphor particles according to claim 10, wherein, in the step, an organosilicon compound is brought into contact with the phosphor and subjected to heat treatment, thereby forming the polysilicon compound on the surface of the crystal phase of the phosphor layer of oxane bonds. The method for producing phosphor particles according to claim 11, wherein the content of Si atoms in the organosilicon compound is 0.001 to 10 parts by mass relative to 100 parts by mass of the core. The method for producing phosphor particles according to claim 11 or 12, wherein the temperature of the heat treatment is 100 to 500°C.

Images