JP5249894B2 - Coated phosphor, wavelength conversion member, LED light emitting device - Google Patents

Description

  The present invention relates to a coated phosphor whose surface is coated with a moisture-proof film, a wavelength conversion member and an LED light-emitting device which are produced using the coated phosphor.

  A light emitting device in which the wavelength of light emitted from a semiconductor light emitting element such as a light emitting diode (LED) is converted by a phosphor to emit light can be formed in a small size and consumes less power than an incandescent light bulb. Features such as the ability to emit light in any color according to the purpose of use, such as white. For this reason, a light-emitting device using a phosphor is a liquid crystal display, a backlight light source such as a mobile phone or a portable information terminal, a display device used for indoor and outdoor advertisements, indicators of various portable devices, lighting switches, or OA (offices). Automation) It can be used as a light source for equipment, etc., and development such as high efficiency or high reliability has been performed.

  Up to now, for example, a light emitting device that emits white light or the like by combining a semiconductor light emitting element that emits blue or blue-violet light or ultraviolet light and a phosphor has been developed. As the body, various oxide and sulfide phosphors are used. However, a phosphor containing, for example, silicate or sulfide may be hydrolyzed by a hydration reaction with moisture in the air, and the useful life of the light-emitting device is reduced due to degradation of the phosphor due to such hydrolysis. There is a problem.

  Therefore, various studies have been made to improve the moisture resistance by surface treatment of the phosphor. For example, in Patent Document 1, a polyorganosiloxane film is formed on the surface of phosphor particles to prevent moisture such as moisture from acting on the phosphor with this moisture-proof coating.

  However, since the polyorganosiloxane coating as in Patent Document 1 has a low density, moisture may penetrate into the polyorganosiloxane matrix, and it is difficult to completely block moisture. There is a problem that the effect of preventing is low.

  On the other hand, in Patent Document 2, the surface of the phosphor is coated with a hydrophobic coating composed of metal oxide particles and a metal oxide matrix, and moisture such as moisture acts on the phosphor with this hydrophobic coating. I try to prevent it.

  In this case, by containing metal oxide particles in the metal oxide matrix, the coating becomes dense and the moisture blocking effect by the metal oxide particles can be expected, so that the moisture-proof performance is improved. be able to.

  However, the inclusion of metal oxide particles increases the brittleness of the coating, and gaps are likely to form at the interface between the metal oxide particles and the matrix, resulting in curing shrinkage when forming a hydrophobic coating on the phosphor surface. There is a problem that cracks are likely to be formed in the coating film, and moisture may enter through the cracks.

  Further, in order to obtain a high moisture blocking effect by the metal oxide particles, it is necessary to increase the content of the metal oxide particles in the coating. That is, FIG. 3 shows a state in which the metal oxide particles 4 are dispersed in the coating 2 coated on the surface of the phosphor 1. As indicated by arrows, moisture such as water vapor can be blocked by the metal oxide particles 4 through the coating 2, but if the amount of the metal oxide particles 4 in the coating 2 is small, a part of the moisture Passes through the gap between the metal oxide particles 4. For this reason, unless the content of the metal oxide particles 4 in the coating 2 is increased, the moisture blocking effect by the metal oxide particles 4 cannot be obtained. However, when the content of the metal oxide particles 4 is increased in this way, gelation or the like is likely to occur in the matrix of the coating 2 due to the interaction between the particles, and the formation of the coating 2 becomes extremely difficult. As a result, the brittleness was further increased, and cracks were more likely to occur in the coating 2, whereas the moisture resistance was reduced.

Japanese Patent Laid-Open No. 10-298544 Japanese Patent Laid-Open No. 9-272866

  The present invention has been made in view of the above points, and can provide a coated phosphor that can form a moisture-proof film as a film having high moisture-proof performance and suppressed generation of cracks, and is excellent in moisture resistance. The object is to provide a wavelength conversion member and an LED light-emitting device having a long service life.

  The coated phosphor according to the present invention is a coated phosphor in which the surface of the phosphor is coated with a moisture-proof film formed by dispersing metal oxide particles in a metal oxide matrix phase, the metal oxide in the moisture-proof film The particles are tabular grains having a particle diameter of 2 nm to 1 μm, a thickness of 1/5 or less of the particle diameter and 100 nm or less.

  According to the present invention, the moisture-proof film is formed by dispersing metal oxide particles in the metal oxide matrix phase, and the moisture-proof film can be densely formed to improve the moisture-proof performance. Further, since the metal oxide particles are tabular particles, the metal oxide particles are oriented and dispersed in the moisture-proof film so that the flat surface is parallel to the film surface of the moisture-proof film. Therefore, it is possible to obtain a high moisture blocking effect and improve the moisture-proof performance. The flat metal oxide particles can obtain a moisture blocking effect even with a small content, and the moisture content of the moisture barrier layer can be increased by reducing the content of the metal oxide particles. It is possible to prevent cracks from occurring.

  In the present invention, the metal oxide particles are made of a metal oxide selected from one or more of Si, Ti, Al, Zr, Ge, and Y.

  By using these metal oxide particles, a moisture-proof film having high moisture-proof performance can be formed.

  In the present invention, the metal oxide matrix phase is formed of a metal oxide formed from a metal alkoxide represented by at least one of chemical formula (1) and chemical formula (2), a hydrolyzate thereof, or a condensate thereof. It is characterized by that.

Chemical formula (1) M ¹ (OR ¹ ) _m
Formula _{^{(2) M 2 (OR 2}} ) n-x (R 3) x
(M ¹ and M ² are metals selected from Si, Ti, Al, Zr, Ge, and Y. R ¹ and R ² are alkyl groups or hydrogen, R ³ is an alkyl group, m is the valence of M ¹ , n is the same integer as the valence of M ^2. x is an integer of 1 or more, and n> x.)
According to the present invention, a moisture-proof film having a high moisture-proof performance is formed by the matrix phase of the metal oxide formed from the metal alkoxide represented by the chemical formula (1) or the chemical formula (2), the hydrolyzate thereof or the condensate thereof. Is something that can be done.

  In the present invention, the moisture-proof film has a thickness of 10 nm to 1000 nm.

  According to the present invention, it is possible to obtain high moisture blocking performance by the moisture-proof film without inhibiting the light transmission by the moisture-proof film.

  The wavelength conversion member according to the present invention is characterized in that the above-described coated phosphor is formed by dispersing in a translucent medium made of silicone resin or glass, and has excellent moisture resistance. A wavelength conversion member having a long service life can be obtained using.

  Moreover, the LED light-emitting device according to the present invention is characterized by being formed using the above-described wavelength conversion member, and an LED light-emitting device having a long service life can be obtained.

  According to the coated phosphor according to the present invention, since the moisture-proof film is formed by dispersing metal oxide particles in the metal oxide matrix phase, the moisture-proof film can be densely formed to improve the moisture-proof performance. Since the metal oxide particles are tabular grains, the metal oxide particles are oriented so that the flat surface of the metal oxide particles is parallel to the film surface of the moisture-proof film and dispersed in the moisture-proof film. It is possible to obtain a high moisture blocking effect by the metal oxide particles and to improve the moisture proof performance. Since the flat metal oxide particles can obtain a moisture blocking effect even with a small content, the metal oxide particle content can be reduced to increase the flexibility of the moisture-proof layer. The generation of cracks in the layer can be suppressed. As described above, the moisture-proof film can be formed as a film having high moisture-proof performance and suppressed generation of cracks, and a coated phosphor excellent in moisture resistance can be obtained.

  Moreover, the wavelength conversion member and LED light-emitting device which concern on this invention are formed using such a covering fluorescent substance excellent in moisture resistance, and can extend a service life.

An example of embodiment of the covering fluorescent substance concerning this invention is shown, (a) is sectional drawing, (b) is one part expanded sectional view. It is sectional drawing which shows an example of embodiment of the LED light-emitting device of this invention. It is a partial expanded sectional view of the conventional coated phosphor.

  Embodiments of the present invention will be described below.

In the present invention, the phosphor is not particularly limited, and any phosphor used for wavelength conversion of a light emitting device such as LED illumination can be used. For example, (Sr, Ca) S: Eu, Y ₃ (Al, Ga) ₅ O ₁₂ : Ce, (Y, Gd) ₃ Al ₅ O ₁₂ : Ce, CaGa ₂ S ₄ : Eu, (Ca, Sr) ₂ Si ₅ N ₈ : Eu, SrSiO _{2 N 2: Eu, CaSiN 2:} Eu, Ca 3 Sc 2 Si 3 O 12: Ce, CaGa 2 S 4: Eu, 2SiO 4: Eu , and the like.

  The coated phosphor A according to the present invention is obtained by coating the surface of particles of the phosphor 1 with a moisture-proof film 2, and the moisture-proof film 2 is a film in which metal oxide particles 4 are dispersed in a metal oxide matrix phase 3. It is formed.

  The metal oxide matrix phase 3 of the moisture-proof film 2 includes a metal oxide formed by hydrolyzing and condensing a metal alkoxide represented by the following chemical formula (1), a hydrolyzate thereof, or a condensate thereof. The metal alkoxide represented by the following chemical formula (2) or a hydrolyzate thereof or a condensate thereof is formed from a metal oxide formed by hydrolysis and condensation.

Chemical formula (1) M ¹ (OR ¹ ) _m
Formula _{^{(2) M 2 (OR 2}} ) n-x (R 3) x
Here, in the chemical formulas (1) and (2), M ¹ and M ² are metals selected from Si, Ti, Al, Zr, Ge, and Y, respectively. R ¹ and R ² are alkyl groups or hydrogen, and may all be the same or different. R ³ is an alkyl group, which may all be the same or different. Further m is integer equal the valence of M ^1, n is an integer equal the valence of M ^2. Further, x is an integer of 1 or more, and n> x.

It said compound of Formula (1) is, R ¹ are all methyl group, an ethyl group, a propyl group, may be a metal alkoxide is an alkyl group such as butyl group, a part of R ¹ is an alkyl group The remainder may be hydrogen. When all of R ¹ are hydrogen, a hydrolyzate of metal alkoxide can be used. The alkyl group of R ^{1 in} the chemical formula (1) is not particularly limited, but it is preferable that the number of C is in the range of 1 to 4.

  Specific examples of the metal alkoxide of the chemical formula (1) include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, and tetrakis (2-methoxyethoxy) silane. Substituted or unsubstituted alkoxysilanes; aluminum triethoxide, aluminum tri-n-propoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum triisobutoxide, aluminum tri-sec-butoxide, aluminum tri -Tert-butoxide, aluminum tris (hexyl oxide), aluminum tris (2-ethylhexyl oxide), aluminum tris (2-methoxyethoxide), aluminum tris (2-ethoxy Substituted or unsubstituted aluminum alkoxides such as aluminum tris (2-butoxyethoxide); titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetraisopropoxide, titanium tetra-n-butoxide, Titanium alkoxides such as titanium tetra-sec-butoxide, titanium tetrakis (2-ethylhexyl oxide); zirconium tetraethoxide, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra Zirconium alkoxides such as -sec-butoxide, zirconium tetrakis (2-ethylhexyl oxide); germanium tetraethoxide, germanium tetra-n-propoxide, Germanium alkoxides such as ruthenium tetraisopropoxide, germanium tetra-n-butoxide, germanium tetra-sec-butoxide, germanium tetrakis (2-ethylhexyl oxide); yttrium hexaethoxide, yttrium hexaethoxide-n-propoxide Yttrium alkoxides such as yttrium hexaethoxide isopropoxide, yttrium hexaethoxide-n-butoxide, yttrium hexaethoxide-sec-butoxide, yttrium hexaethoxide (2-ethylhexyl oxide); In addition, a partial hydrolysis condensate that is an oligomer of these metal alkoxides, or a mixture with each other or with a metal alkoxide that is a monomer may also be used. Can.

The compounds of the above formula (2) is, R ² are all methyl group, an ethyl group, a propyl group, may be a metal alkoxide is an alkyl group such as butyl group, a part of R ² is an alkyl group The remainder may be hydrogen. Further, it may be a hydrolyzate of metal alkoxide in which all of R ² is hydrogen. Further, at least one alkyl group R ³ is bonded to the metal M ² , and this alkyl group R ³ may be linear or branched, and ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl are substituted. Examples of the substituted alkyl group include alkoxy-substituted alkyl groups such as 2-methoxyethyl, 2-ethoxyethyl, and 2-butoxyethyl. The alkyl group of R ^{2 in} the chemical formula (2) preferably has a C number in the range of 1 to 4, and the alkyl group of R ³ has a C number in the range of 1 to 8. Is preferred.

  Specific examples of the alkyl-substituted metal alkoxide of the chemical formula (2) include methyltrimethoxysilane, dimethyldimethoxysilane, methyldimethoxysilane, trimethylmethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, and n-butyltrimethoxysilane. , Methoxysilanes such as n-pentyltrimethoxysilane, n-hexyltrimethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, methylvinyldimethoxysilane; methyltriethoxysilane, dimethyldiethoxysilane Ethoxysilanes such as methyldiethoxysilane, trimethylethoxysilane, vinyltriethoxysilane, methylvinyldiethoxysilane; methyltri-n-propoxy And propoxysilanes such as methyltriisopropoxysilane; substituted alkoxysilanes such as methyltris (2-methoxyethoxy) silane, vinyltris (2-methoxyethoxy) silane, Partial hydrolysis and condensate can also be used. In addition, metal alkoxides whose metal species are aluminum, titanium, zirconium, germanium, and yttrium can be used in the same manner.

  The metal oxide matrix phase 3 of the moisture-proof film 2 can be formed using either one of the compound of the chemical formula (1) and the compound of the chemical formula (2), and the compound of the chemical formula (1) The metal oxide matrix phase 3 of the moisture-proof film 2 can also be formed by using the compound of the chemical formula (2) together.

  In the present invention, the metal oxide particles 4 may be made of a metal oxide selected from Si, Ti, Al, Zr, Ge, and Y. Specifically, silicon dioxide (silica ), Aluminum oxide (alumina), titanium dioxide, zirconium oxide (zirconium), germanium oxide, yttrium oxide, and simple oxides and composite oxides composed of two or more of them. In addition to being used alone, two or more can be used in combination.

  In the present invention, as the metal oxide particles 4, particles having a plate shape (flaky shape) having a particle diameter of 2 nm to 1 μm and a thickness of 1/5 or less and 100 nm or less of the particle diameter are used.

  Next, the phosphor 1 is formed by the moisture-proof film 2 formed by dispersing the metal oxide particles 4 in the matrix phase 3 of the metal oxide formed from the compound of the chemical formula (1) or the chemical formula (2) or the condensate thereof. A method for producing the coated phosphor A by coating the surface will be described. There are various coating methods, and although there are no particular limitations, a sol-gel coating method, a spray drying method, and a fluidized bed coating method will be described.

  In the sol-gel coating method, first, particles of the phosphor 1 are dispersed in a liquid medium, and while stirring, the compound of the chemical formula (1) or the chemical formula (2) or a condensate thereof, or a solution thereof, and the metal oxide particles 4 And the hydrolysis and condensation of the compound of the chemical formula (1) or the chemical formula (2) or the condensate thereof are allowed to proceed on the particle surface of the phosphor 1, and the matrix phase 3 of the metal oxide is added. The moisture-proof film 2 can be formed as a film in which the metal oxide particles 4 are dispersed.

  Examples of the liquid medium include water, alcohol solvents such as methanol, ethanol, propanol, isopropanol, and butanol; carbonization such as toluene, xylene, cyclohexane, methylcyclohexane, petroleum ether, petroleum benzine, gasoline, and naphtha. Examples include hydrogen solvents; ether solvents such as diethyl ether and tetrahydrofuran; ester solvents such as ethyl acetate and butyl acetate; and ketone solvents such as acetone and methyl ethyl ketone. Or may be used as a mixture with each other.

  When the phosphor 1 is treated with a metal alkoxide in an organic solvent as described above, a stoichiometric amount or an excessive amount of water can be present in the system in order to hydrolyze the metal alkoxide. Water may be used in the system in which the phosphor 1 is first dispersed, and may be added together with a metal alkoxide having a relatively low hydrolysis rate, or may be added to the system separately from the metal alkoxide. Alternatively, the metal alkoxide is adhered to the particle surface of the phosphor 1, and the solvent 1 is removed by distillation or the phosphor 1 to which the metal alkoxide is adhered is recovered by filtration, and then the phosphor 1 is mixed with vapor or liquid phase water. The metal alkoxide on the surface of the phosphor 1 can be hydrolyzed and condensed to form a metal oxide matrix coating.

  In the spray drying method, a dispersion is prepared by adding a compound of chemical formula (1) or chemical formula (2) or a condensate thereof and metal oxide particles to a liquid in which phosphor 1 is dispersed in a liquid medium. The liquid 1 is sprayed, and the phosphor 1 is dried by drying the droplet enclosing the phosphor 1 with the compound of the chemical formula (1) or chemical formula (2) or the condensate thereof and the metal oxide particles 4. A moisture-proof film 2 can be formed by attaching a film in which the metal oxide particles 4 are dispersed in the metal oxide matrix phase 3 to the surface of the particles. As the liquid medium, the organic solvents exemplified above can be used.

  In the fluidized bed coating method, the compound of the chemical formula (1) or chemical formula (2) or a mixture of the condensate thereof and the metal oxide particles 4 is sprayed, or the compound of the chemical formula (1) or chemical formula (2) or the compound thereof. When the boiling point of the condensate is relatively low, it is vaporized so as to be brought into contact with the particle surface of the phosphor 1 and to attach the metal oxide particles 4. When the phosphor 1 is brought into contact with the compound of the chemical formula (1) or chemical formula (2) or the condensate thereof, the phosphor 1 is fluidized and at the same time the compound of the chemical formula (1) or chemical formula (2) or the condensate thereof. Are supplied together with an inert gas such as nitrogen or argon, and at the same time or after contact, the compound of chemical formula (1) or chemical formula (2) present on the surface of phosphor 1 or a condensate thereof In contact with a stoichiometric or excess amount of water. Water is contacted in the form of a spray or in the gas phase, like the compound of chemical formula (1) or chemical formula (2) or the condensate thereof.

  In any of the above methods, the metal oxide film is formed at a lower temperature and in a shorter time by accelerating the hydrolysis reaction or condensation reaction of the compound of chemical formula (1) or chemical formula (2) or the condensate thereof. In addition, a catalyst may be added. Catalysts include acids such as hydrochloric acid, nitric acid, sulfuric acid and acetic acid; bases such as sodium hydroxide, ammonia and tetramethylammonium hydroxide; carboxylic acids such as hexanoic acid, octanoic acid, 2-ethylhexanoic acid and naphthenic acid Carboxylic acid metal salts such as zinc salts of aluminum; aluminum alkoxides such as aluminum triethoxide, aluminum tri-n-propoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum isobutoxide and their partial hydrolysis Decomposition condensate: diisopropoxy (acetylacetonato) aluminum, di-n-butoxy (acetylacetonato) aluminum, tris (acetylacetonato) aluminum, diisopropoxy (ethylacetoaceto) aluminum, di-n-butoxy Illustrate aluminum chelate compounds such as (ethylacetoacetato) aluminum, n-butoxybis (ethylacetoacetato) aluminum; quaternary ammonium salts such as tetramethylammonium acetate; and amino compounds such as triethanolamine be able to. In addition, amino group-containing alkoxysilanes such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3- (N-2-aminoethyl) propyltrimethoxysilane, which are themselves metal alkoxides, are used in combination with a catalyst. May be. The above catalyst may be added to the system by any method.

  Further, the surface treatment of the phosphor 1 with the compound of the above chemical formula (1) or chemical formula (2) or its condensate by spray drying method or fluidized bed coating method is performed at a normal temperature or a relatively low heating temperature up to 60 ° C. Then, after the phosphor 1 surface-treated by the sol-gel coating method is recovered by filtration, it is further heated at a temperature of 60 to 300 ° C. in order to complete the condensation reaction for forming the metal oxide matrix phase. preferable. The heating time is not particularly limited, but may be about 0.5 to 3 hours.

  In the present invention, when the surface of the phosphor 1 is coated with the moisture-proof film 2 in which the metal oxide particles 4 are dispersed in the metal oxide matrix phase 3 as described above, tabular particles are used as the metal oxide particles 4. Therefore, when the metal oxide matrix phase 3 containing the metal oxide particles 4 is coated on the surface of the phosphor 1, the plate-like metal oxide particles 4 are formed as shown in FIG. As shown in (a), the flat plate surface is oriented so as to be parallel to the film surface of the moisture-proof film 2 made of the metal oxide matrix phase 3, and the metal oxide particles 4 are moisture-proof with the flat plate surfaces overlapping in parallel. It is dispersed in the film 2.

  In the coated phosphor A of the present invention obtained as described above, since the moisture-proof film 2 is formed by dispersing the metal oxide particles 4 in the metal oxide matrix phase 3, the film quality of the moisture-proof film 2 is made dense. Thus, the performance of shielding the penetration of moisture can be improved. Further, as described above, since the metal oxide particles 4 are dispersed in the moisture-proof film 2 in a state where the flat plate surfaces are overlapped in parallel, as shown in FIG. (Shown by an arrow) is blocked by the metal oxide particles 4, and the moisture blocking effect by the metal oxide particles 4 is also added, so that the moisture-proof performance can be increased. If the metal oxide particles 4 are spherical or the like as in the case of FIG. 3 described above, a sufficient moisture blocking effect cannot be obtained unless the content of the metal oxide particles 4 is increased. When the metal oxide particles 4 are flat like the invention, the metal oxide particles 4 overlap each other in the thickness direction of the moisture-proof film 2 as shown in FIG. However, the coverage is increased and a sufficient effect of blocking moisture can be obtained. Accordingly, the amount of the metal oxide particles 4 dispersed in the metal oxide matrix phase 3 can be reduced, and the loss of the flexibility of the moisture-proof film 2 by the metal oxide particles 4 can be reduced. The occurrence of cracks in the film 2 can be suppressed. As a result, the moisture-proof film 2 can be formed as a film having high moisture-proof performance and suppressing the occurrence of cracks, and the coated phosphor A having excellent moisture resistance can be obtained.

  Here, the content of the metal oxide particles 4 in the metal oxide matrix phase 3 of the moisture-proof film 2 is not particularly limited, but is preferably in the range of 3% by mass to 80% by mass, particularly 10%. The range of mass% or more and 50 mass% or less is more preferable. If the content of the metal oxide particles 4 is less than the above range, the effect of densifying the film quality of the moisture-proof film 2 may be insufficient, and the effect of suppressing moisture penetration may be insufficient. On the other hand, if the content of the metal oxide particles 4 exceeds the above range, the film quality flexibility of the moisture-proof film 2 is impaired and the brittleness becomes high, and cracks are likely to occur during the formation of the film.

  Further, as described above, the size of the flat metal oxide particles 4 is set such that the particle diameter is 2 nm to 1 μm and the thickness is 1/5 or less of the particle diameter and 100 nm or less. Those having a particle size of less than 2 nm are not practical and are not practical. On the other hand, if the particle diameter exceeds 1 μm, it is difficult to form a suitable film on the surface of the phosphor 1, and scattering may occur on the surface of the phosphor 1 during light emission, which may deteriorate the light emission characteristics. Further, when the thickness is larger than 1/5 of the particle diameter, the metal oxide particles 4 can be oriented so that the flat surface thereof is parallel to the film surface of the moisture-proof film 2 when the moisture-proof film 2 is formed. It becomes difficult, the overlap in the film thickness direction of the moisture-proof film 2 between the metal oxide particles 4 becomes insufficient, and the moisture blocking effect by the metal oxide particles 4 may be insufficient. Further, when the thickness exceeds 100 nm, it becomes difficult to orient the metal oxide particles 4 so that the flat plate surfaces thereof are parallel to the film surface of the moisture-proof film 2, and the light is scattered on the surface of the phosphor 1 during light emission. May occur and the light emission characteristics may be deteriorated. The lower limit of the thickness of the metal oxide particles 4 is not particularly set, but practically about 1 nm is the lower limit of the thickness. Here, in the present invention, the particle diameter of the flat metal oxide particles 4 refers to the average value of the major axis diameter and the minor axis diameter of the flat plate surface. Is an actual measurement value measured with an electron microscope.

  The thickness of the moisture-proof film 2 that covers the surface of the phosphor 1 is preferably in the range of 10 nm to 1000 nm. If the film thickness of the moisture-proof film 2 is less than 10 nm, the effect of blocking moisture may not be sufficiently obtained, and the improvement of moisture resistance may be insufficient. On the contrary, when the film thickness of the moisture-proof film 2 exceeds 1000 nm, the light-transmitting property of the moisture-proof film 2 is lowered, and the light emission efficiency of wavelength conversion by the phosphor 1 may be lowered.

  Next, the wavelength conversion member and LED light-emitting device produced using the coated phosphor of the present invention obtained as described above will be described.

  FIG. 2 shows an example of the LED light-emitting device B. The LED chip 10 is mounted on the surface of the mounting substrate 20 provided with the conductor pattern 23 via the stress-reducing submount member 30. Reference numeral 10 denotes a wire 14 connected to the conductor pattern 23. A dome-shaped optical member 60 made of a translucent material is attached to the surface of the mounting substrate 20 so as to surround the LED chip 10, and the light distribution of the light emitted from the LED chip 10 is controlled by the optical member 60. It is made to do. The inner surface side of the optical member 60 is filled with a translucent sealing material 50 that seals the LED chip 10 and the bonding wire 14. Further, a dome-shaped wavelength conversion member 70 is attached to the mounting substrate 20 so as to cover the optical member 60 through the space 80. The wavelength conversion member 70 is formed by dispersing the coated phosphor A of the present invention in a translucent medium having a refractive index smaller than that of the phosphor 1 particles, such as silicone resin or glass.

  Here, in the LED light-emitting device B formed as described above, for example, a GaN-based blue LED chip that emits blue light is used as the LED chip 10, and as a coated phosphor dispersed in the wavelength conversion member 70, Green phosphor particles that are excited by light emitted from the LED chip 10 to emit green light, and red phosphor particles that are excited by light emitted from the LED chip 10 to emit red light can be used. . When the LED chip 10 emits light and emits blue light, when the light passes through the wavelength conversion member 70, part of the blue light is converted to green by the green phosphor particles, and the blue light The other part is converted into red by red phosphor particles, and blue, green and red light are mixed and emitted from the LED light emitting device B as white light. Therefore, the LED light-emitting device B can be used as an illumination device that emits white light.

  Next, the present invention will be specifically described with reference to examples.

Example 1
To 700 parts by mass of isopropanol and 6 parts by mass of ion-exchanged water and uniformly mixed, 100 parts by mass of a phosphor (matrix (Sr, Ca, Ba) ₃ SiO ₅ : Eu, average particle size of 15 μm) and a particle size A phosphor dispersion liquid was prepared by dispersing 1.0 part by mass of flaky silica particles having a thickness of 80 nm and a thickness of 10 nm. Moreover, the alkoxysilane solution which melt | dissolved 30 mass parts of methyltrimethoxysilane and 2.5 ml of 0.1 N hydrochloric acid aqueous solution in 700 mass parts of isopropanol was prepared. And the slurry dispersion liquid was obtained by adding an alkoxysilane solution, stirring a fluorescent substance dispersion liquid.

  Then, the slurry dispersion is supplied to a spray dryer under the conditions of a nitrogen atmosphere (oxygen concentration of 3% or less), 150 ° C., an atomizer rotational speed of 15000 rpm, and a liquid supply speed of 40 g / min, and spray-dried to volatilize isopropanol. At the same time, a coating of flaky silica particles dispersed in polymethylsiloxane produced by hydrolysis and polycondensation of methyltrimethoxysilane was coated on the phosphor surface, which was further heated at 300 ° C. for 1 hour to dry. As a result, a coated phosphor having a moisture-proof film formed thereon was obtained.

(Example 2)
In Example 1, instead of 1.0 part by mass of flaky silica particles, 0.4 part by mass of tabular alumina particles having a particle diameter of 250 nm and a thickness of 20 nm was used. Otherwise, in the same manner as in Example 1, a moisture-proof film was formed by coating the phosphor surface with a coating in which tabular alumina particles were dispersed in polymethylsiloxane produced by hydrolysis and polycondensation of methyltrimethoxysilane. The formed coated phosphor was obtained.

(Example 3)
To 700 parts by mass of isopropanol and 6 parts by mass of ion-exchanged water and uniformly mixed, 100 parts by mass of a phosphor (matrix (Sr, Ca, Ba) ₃ SiO ₅ : Eu, average particle size of 15 μm) and a particle size A phosphor dispersion liquid was prepared by dispersing 0.4 parts by mass of tabular alumina particles having a thickness of 250 nm and a thickness of 20 nm. Moreover, the alkoxysilane solution which melt | dissolved 30 mass parts of tetramethoxysilane and 2.5 ml of 0.1 N hydrochloric acid aqueous solution in 700 mass parts of isopropanol was prepared. And the slurry dispersion liquid was obtained by adding an alkoxysilane solution, stirring a fluorescent substance dispersion liquid.

  Then, the slurry dispersion is supplied to a spray dryer under the conditions of a nitrogen atmosphere (oxygen concentration of 3% or less), 150 ° C., an atomizer rotational speed of 15000 rpm, and a liquid supply speed of 40 g / min, and spray-dried to volatilize isopropanol. And coating the phosphor surface with a coating in which tabular alumina particles are dispersed in polysiloxane produced by hydrolysis and polycondensation of tetramethoxysilane, and further heating it at 300 ° C. for 1 hour to dry it. Thus, a coated phosphor having a moisture-proof film formed thereon was obtained.

Example 4
To 700 parts by mass of isopropanol and 6 parts by mass of ion-exchanged water and uniformly mixed, 100 parts by mass of a phosphor (matrix (Sr, Ca, Ba) ₃ SiO ₅ : Eu, average particle size of 15 μm) and a particle size A phosphor dispersion liquid was prepared by dispersing 0.4 parts by mass of tabular alumina particles having a thickness of 250 nm and a thickness of 20 nm. Moreover, the alkoxysilane solution which melt | dissolved 32 mass parts of methyl trimethoxysilane, 3 mass parts of zirconium tetra-n-butoxide, and 2.5 ml of 0.1 N hydrochloric acid aqueous solution in 700 parts of isopropanol was obtained. And the slurry dispersion liquid was obtained by adding an alkoxysilane solution, stirring a fluorescent substance dispersion liquid.

  Then, the slurry dispersion is supplied to a spray dryer under the conditions of a nitrogen atmosphere (oxygen concentration of 3% or less), 150 ° C., an atomizer rotational speed of 15000 rpm, and a liquid supply speed of 40 g / min, and spray-dried to volatilize isopropanol. And coating the phosphor surface with a film in which tabular alumina particles are dispersed in polysiloxane produced by hydrolysis and polycondensation of methyltrimethoxysilane and zirconium tetra-n-butoxide, and this is further applied at 300 ° C. The coated phosphor having a moisture-proof film was obtained by heating for 1 hour and drying.

(Comparative Example 1)
To 700 parts by mass of isopropanol and 6 parts by mass of ion-exchanged water and uniformly mixed, 100 parts by mass of a phosphor (matrix (Sr, Ca, Ba) ₃ SiO ₅ : Eu, average particle size of 15 μm) and a particle size A phosphor dispersion liquid was prepared by dispersing 1.0 part by mass of 80 nm spherical silica particles. Moreover, the alkoxysilane solution which melt | dissolved 30 mass parts of methyltrimethoxysilane and 2.5 ml of 0.1 N hydrochloric acid aqueous solution in 700 mass parts of isopropanol was prepared. And the slurry dispersion liquid was obtained by adding an alkoxysilane solution, stirring a fluorescent substance dispersion liquid.

  Then, the slurry dispersion is supplied to a spray dryer under the conditions of a nitrogen atmosphere (oxygen concentration of 3% or less), 150 ° C., an atomizer rotational speed of 15000 rpm, and a liquid supply speed of 40 g / min, and spray-dried to volatilize isopropanol. At the same time, a coating film in which spherical silica particles are dispersed in polymethylsiloxane produced by hydrolysis and polycondensation of methyltrimethoxysilane is coated on the surface of the phosphor, which is further heated at 300 ° C. for 1 hour to be dried. Thus, a coated phosphor having a moisture-proof film formed thereon was obtained.

(Comparative Example 2)
In Comparative Example 1, instead of 1.0 part by mass of the spherical silica particles, 1.0 part by mass of tabular alumina particles having a particle diameter of 1.5 μm and a thickness of 180 nm was used. Otherwise, in the same manner as in Comparative Example 1, the moisture-proof film was formed by coating the phosphor surface with a coating in which tabular alumina particles were dispersed in polymethylsiloxane produced by hydrolysis and polycondensation of methyltrimethoxysilane. The formed coated phosphor was obtained.

  About Examples 1-4 and Comparative Examples 1-2, the kind of metal alkoxide used for formation of the metal oxide matrix phase of a moisture-proof film, and the kind of metal oxide particles dispersed in the metal oxide matrix phase 1 is shown collectively.

  Further, the coated phosphors obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were cut by FIB processing, and the thickness of the moisture-proof film was measured by observing the cross section with a transmission electron microscope (TEM). .

  And the light-emitting luminance was evaluated about the coated fluorescent substance obtained in Examples 1-4 and Comparative Examples 1-2. The evaluation of the emission luminance is performed by measuring the emission luminance of the phosphor before coating and the coating phosphor after coating using a fluorescence spectrophotometer (“FP-6000 Series” manufactured by JASCO Corporation). Then, the retention rate of the emission luminance of the phosphor after the coating treatment was determined according to the following formula.

Maintenance rate after coating (%)
= (Emission luminance after coating treatment / emission luminance before coating treatment) × 100
Moreover, the moisture resistance test was done using the coating fluorescent substance of Examples 1-4 and Comparative Examples 1-2. The moisture resistance test was performed by putting the coated phosphor powder into a glass container and leaving it in an environment of 85 ° C. and a relative humidity of 85% for 500 hours.

  Thus, the moisture resistance of the fluorescent substance of Examples 1-4 and Comparative Examples 1-2 which performed the moisture resistance test was evaluated. For the evaluation of moisture resistance, the emission luminance before and after the moisture resistance test of the coated phosphor is measured, respectively, and the retention rate of the emission luminance after the moisture resistance test is determined according to the following formula from the amount of change before and after the moisture resistance test. This was used as an index of moisture resistance.

Maintenance rate after humidity resistance test (%)
= (Luminance after moisture resistance test / Luminance before moisture resistance test) × 100

  As can be seen in Table 1, all of Examples 1 to 4 maintain high emission luminance even after the moisture resistance test, and it is confirmed that the moisture resistance is improved.

  On the other hand, in Comparative Example 1 using spherical metal oxide particles, the light emission luminance after the moisture resistance test was lowered and the moisture resistance was inferior. Further, when using flat metal oxide particles, even in Comparative Example 2 having a large particle diameter and a large thickness, the light emission luminance after the moisture resistance test was lowered and the moisture resistance was inferior.

DESCRIPTION OF SYMBOLS 1 Phosphor 2 Moisture-proof film 3 Metal oxide matrix phase 4 Metal oxide particle

Claims (6)

  A phosphor coated with a moisture-proof film formed by dispersing metal oxide particles in a metal oxide matrix phase on the surface of the phosphor, and the metal oxide particles in the moisture-proof film have a particle diameter of 2 nm to 1 μm. A coated phosphor characterized in that the phosphor is a tabular grain having a thickness of 1/5 or less of the particle diameter and 100 nm or less.   2. The coated phosphor according to claim 1, wherein the metal oxide particles are made of a metal oxide selected from one or more of Si, Ti, Al, Zr, Ge, and Y. The metal oxide matrix phase is formed of a metal oxide formed from a metal alkoxide represented by at least one of chemical formula (1) and chemical formula (2), a hydrolyzate thereof, or a condensate thereof. The coated phosphor according to claim 1 or 2.
Chemical formula (1) M ¹ (OR ¹ ) _m
Formula _{^{(2) M 2 (OR 2}} ) n-x (R 3) x
(M ¹ and M ² are metals selected from Si, Ti, Al, Zr, Ge, and Y. R ¹ and R ² are alkyl groups or hydrogen, R ³ is an alkyl group, m is the valence of M ¹ , n is the same integer as the valence of M ^2. x is an integer of 1 or more, and n> x.)   The coated phosphor according to any one of claims 1 to 3, wherein the moisture-proof film has a thickness of 10 nm to 1000 nm.   5. A wavelength conversion member formed by dispersing the coated phosphor according to claim 1 in a translucent medium made of silicone resin or glass.   An LED light emitting device, comprising the wavelength conversion member according to claim 5.

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