Phosphor paint, coating film, phosphor substrate and lighting device

Abstract

A fluorescent coating including fluorescent particles and a curable resin component. The viscosity of the fluorescent coating, measured using a type-B viscometer at 25°C at a rotation speed of 20 rpm, is from 60 dPa∙s to 450 dPa∙s. A coating film (fluorescent layer), fluorescent substrate, and lighting equipment can be made using this fluorescent coating.

Description

Phosphor paint, coating film, phosphor substrate and lighting device

[0001] The present invention relates to a phosphor paint, a coating film, a phosphor substrate, and a lighting device.

[0002] 2. Description of the Related Art Various developments have been made regarding lighting devices using LEDs (Light Emitting Devices). Not only the development of LEDs themselves, but also the development of mounting boards on which LEDs are mounted are known.

[0003] For example, Example 2 of Patent Document 1 describes that (i) a glass binder paint containing 30 vol % phosphor was applied to the surface of a glass substrate to form a phosphor layer 200 μm thick, (ii) a plurality of CSPs were bonded onto the glass substrate to obtain a mounting substrate for LED lighting, and (iii) when electricity was applied to the mounting substrate, problems of glare and multiple shadows were reduced despite light being emitted from the plurality of CSPs. (CSP is an abbreviation for Chip Scale Package or Chip Size Package, and is a package-less device in which an LED chip is wrapped in phosphor resin, consisting only of the LED chip and phosphor resin.)

[0004] International Publication No. 2019 / 093339

[0005] In Example 2 of Patent Document 1, a phosphor layer having a thickness of 200 μm is formed on a glass substrate using a "glass binder paint" containing phosphor. However, since a sintering process at high temperatures is usually required to fully harden the glass binder paint, there is room for improvement in terms of the ease of forming the phosphor layer. In addition, the housing / substrate to which the glass binder paint is applied is also subject to limitations such as heat resistance and optimization of the expansion coefficient.

[0006] The present invention has been made in view of the above circumstances, and one of the objects of the present invention is to provide a material that can be used to easily form a phosphor layer.

[0007] As a result of extensive research, the present inventors have completed the invention provided below and solved the above-mentioned problems.

[0008] According to the present invention, there is provided a phosphor coating material containing phosphor particles and a curable resin component, the phosphor coating material having a viscosity of 60 dPa·s or more and 450 dPa·s or less when measured at 25°C and 20 rpm using a B-type viscometer.

[0009] The present invention also provides a coating film formed from the above-mentioned phosphor coating material.

[0010] The present invention also provides a phosphor substrate comprising the coating film described above.

[0011] Furthermore, according to the present invention, there is provided a lighting device comprising an insulating substrate, a coating film formed on one side of the insulating substrate using the above-mentioned phosphor paint, and a light-emitting element installed on the surface of the coating film opposite the insulating substrate.

[0012] By using the phosphor coating material of the present invention, the phosphor layer can be easily provided.

[0013] 1 is a schematic cross-sectional view of a lighting device, and FIG. 2 is a diagram for explaining an LED chip without a reflector and an LED chip with a reflector.

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and descriptions thereof will be omitted where appropriate. All drawings are for illustrative purposes only. The shapes and dimensional ratios of each component in the drawings do not necessarily correspond to actual products.

[0015] The term "(meth)acrylic" in this specification represents a concept that encompasses both acrylic and methacrylic. The same applies to similar terms such as "(meth)acrylate." The term "phosphor particles" in this specification may refer to "phosphor powder," which is an aggregate of phosphor particles, depending on the context. For example, in the case of the "median diameter D of phosphor particles" described below, ５０ " is a value determined based on the particle size distribution of phosphor powder, which is an aggregate of phosphor particles.

[0016] <Phosphor Paint> The phosphor paint of this embodiment contains phosphor particles and a curable resin component. The viscosity of the phosphor paint of this embodiment, measured using a Brookfield viscometer at 25°C and 20 rpm, is 60 dPa·s or more and 450 dPa·s or less. The content of the phosphor particles in the total non-volatile components is 25 vol% or more and 60 vol% or less.

[0017] The phosphor coating material of this embodiment contains a curable "resin component" instead of a glass binder. This allows the phosphor layer to be formed relatively easily without the need for high-temperature sintering.

[0018] The absence of the need for high-temperature sintering means that usable phosphors are not limited. Specifically, when attempting to obtain a cured film using a glass binder, firing at a high temperature of approximately 600°C is required. When such high temperatures are required, a phosphor that can withstand high temperatures must be selected, which may limit the usable phosphors. Furthermore, peeling is likely to occur when cooling from high temperatures. However, by preparing a phosphor coating using a curable resin component, a phosphor layer that is less likely to peel can be formed without the need for a high temperature of approximately 600°C. The absence of the need for high-temperature sintering also has the advantage of fewer restrictions on the heat resistance and expansion coefficient optimization of the housing / substrate on which the coating is applied or printed.

[0019] Furthermore, the use of a curable resin component makes it easy to form a moderately thin phosphor layer by coating or printing. This is particularly effective when the phosphor coating contains a high content of phosphor particles. In particular, in this embodiment, since the viscosity is 60 dPa·s or more and 450 dPa·s or less, a phosphor layer (a coating film containing phosphor particles) of moderate thickness and minimal unevenness can be formed on a substrate, for example, by a screen printing method suitable for mass production.

[0020] In this embodiment, by using appropriate materials in appropriate amounts, a phosphor coating material having a viscosity of 60 dPa·s or more and 450 dPa·s or less can be obtained. Specifically, the phosphor coating material of this embodiment can be produced by using appropriate amounts of phosphor particles having an appropriate particle size distribution, an appropriate amount of a suitable flowability modifier, an appropriate amount of a suitable solvent, etc.

[0021] The components contained in the phosphor coating material of this embodiment, its physical properties, etc. will be described below.

[0022] (Phosphor Particles) The phosphor coating material of this embodiment contains phosphor particles. The phosphor particles may be any particles that emit fluorescence when exposed to light emitted from the light-emitting element. Depending on the desired color tone, color temperature, etc., only one type of specific phosphor particle may be used, or two or more types of phosphor particles may be used in combination.

[0023] The phosphor particles include CASN phosphors, SCASN phosphors, La ３ Si ６ N １１ Sr-based phosphor ２ Si ５ N ８ Ba-based phosphor ２ Si ５ N ８ The phosphors may be one or more selected from the group consisting of α-sialon-based phosphors, β-sialon-based phosphors, LuAG-based phosphors, and YAG-based phosphors. These phosphors usually contain an activator element such as Eu or Ce.

[0024] The CASN-based phosphor (a type of nitride phosphor) preferably contains Eu. The CASN-based phosphor is, for example, a compound represented by the formula CaAlSiN ３ :Eu ２＋ and Eu ２＋ The term "CASN-based phosphor containing Eu" as used herein means a red phosphor having as its matrix a crystal of alkaline earth silicon nitride, and which uses as an activator an element selected from the group consisting of fluorine, fluorine, and arsenic. In the definition of the CASN-based phosphor containing Eu in this specification, SCASN-based phosphors containing Eu are excluded.

[0025] The SCASN phosphor (a type of nitride phosphor) preferably contains Eu. The SCASN phosphor is, for example, a phosphor represented by the formula (Sr, Ca)AlSiN３ :Eu ２＋ and Eu ２＋ This refers to a red phosphor that uses as an activator a crystal of alkaline earth silicon nitride as a base material.

[0026] La ３ Si ６ N １１ Specifically, the La-based phosphor is ３ Si ６ N １１ :Ce phosphor, etc. This usually converts the wavelength of blue light from a blue LED into yellow light.

[0027] Sr ２ Si ５ N ８ Specifically, the Sr ２ Si ５ N ８ :Eu ２＋ Phosphors and Sr ２ Si ５ N ８ : Ce ３＋ These usually convert the wavelength of blue light from a blue LED into yellow to red light.

[0028] Ba ２ Si ５ N ８ Specifically, the Ba-based phosphor is ２ Si ５ N ８ :Eu, which normally converts the wavelength of blue light from a blue LED into orange to red light.

[0029] The α-sialon phosphor preferably contains Eu. The α-sialon containing Eu is, for example, a compound represented by the general formula: M ｘ EU ｙ Si １２－（ｍ＋ｎ） Al （ｍ＋ｎ） O ｎ N １６－ｎ In the general formula, M is one or more elements selected from the group consisting of Li, Mg, Ca, Y, and lanthanide elements (excluding La and Ce), including at least Ca, and when the valence of M is a, ax+2y=m, where x is 0<x≦1.5, 0.3≦m<4.5, and 0<n<2.25.

[0030] The β-sialon phosphor preferably contains Eu. The β-sialon containing Eu is, for example, a β-sialon represented by the general formula Si ６－ｚ Al ｚ O ｚ N ８－ｚ :Eu ２＋ (0<Z≦4.2), and Eu ２＋ The phosphor is made of β-sialon in which a solid solution of β-sialon and β-sialon is formed. In the general formula, the Z value and the europium content are not particularly limited. The Z value is, for example, more than 0 and not more than 4.2, and from the viewpoint of further improving the luminescence intensity of the β-sialon, it is preferably 0.005 or more and 1.0 or less. Furthermore, the europium content is preferably 0.1 mass % or more and 2.0 mass % or less.

[0031] The LuAG phosphor generally refers to a lutetium aluminum garnet crystal. In consideration of application to lighting devices, the LuAG is preferably a LuAG:Ce phosphor. More specifically, the LuAG is ３ Al ５ O １２ However, the composition of LuAG does not necessarily have to be stoichiometric.

[0032] The YAG-based phosphor usually means yttrium aluminum garnet crystal. In consideration of application to lighting devices, the YAG-based phosphor is preferably activated with Ce. More specifically, the YAG-based phosphor is Y ３ Al ５ O １２ However, the composition of the YAG-based phosphor does not necessarily have to be stoichiometric.

[0033] Commercially available phosphor particles may be used. Examples of commercially available phosphor particles include Alonbright (registered trademark) from Denka Co., Ltd. Other commercially available products include those from Mitsubishi Chemical Corporation.

[0034] Median diameter D of phosphor particles ５０ is preferably 1 μm or more and 20 μm or less, more preferably 5 μm or more and 15 μm or less. ５０By appropriately adjusting the amount of the phosphor coating, for example, the flowability of the phosphor coating can be adjusted, making it easier to form a thin and uniform coating film.

[0035] It is preferable that two or more maxima are observed in the particle size distribution curve of the phosphor particles. Specifically, it is preferable that maxima are observed in both the particle size region of 1 μm to 6 μm and the particle size region of 10 μm to 25 μm. The presence of two or more maxima means that the phosphor particles contain both large and small particles. Since the small particles enter the "gaps" between the large particles, it is easier to increase the phosphor particle content compared to when only large particles are used. Furthermore, even if the phosphor particle content is increased, the physical properties of the paint are easily maintained. Furthermore, when formed into a coating film, the light emitted from the light-emitting element becomes less likely to transmit.

[0036] Median diameter D of phosphor particles ５０ The particle size distribution curve can be adjusted by devising a method for preparing phosphor particles, by appropriately pulverizing the phosphor particles, or by appropriately mixing two or more phosphor particles with different particle sizes.

[0037] The particle size distribution curve of the phosphor particles can be measured by dispersing the raw material phosphor particles in a dispersion medium using an ultrasonic homogenizer and then measuring the particle size distribution using a laser diffraction / scattering particle size distribution measuring device. ５０ For details of the dispersion process and the measuring device, please refer to the examples described later. ５０ and particle size distribution curves are measured on a volume basis.

[0038] The phosphor coating of this embodiment may contain only one type of phosphor particles, or may contain two or more types. The content of the phosphor particles in the total non-volatile components of the phosphor coating is, for example, 25 vol% to 60 vol%. This content is preferably 30 vol% to 60 vol%, more preferably 35 vol% to 60 vol%, and even more preferably 40 vol% to 50 vol%.

[0039] By increasing the phosphor particle content in the total non-volatile components of the phosphor paint to 25 vol% or more, for example, light emitted from a light-emitting element can be sufficiently converted into fluorescence. Other benefits include further improved coating or printing suitability. A moderately high phosphor particle content in the phosphor paint reduces the flowability of the phosphor paint, thereby facilitating the formation of a phosphor layer with an appropriate thickness. Increasing the phosphor particle content in the total non-volatile components of the phosphor paint to 25 vol% or more also has the advantage of reducing the likelihood of cracks occurring in the phosphor layer. Based on general knowledge, one cause of cracks is thought to be the difference in thermal expansion coefficient between the phosphor layer and the substrate on which the phosphor layer is formed. By increasing the phosphor particle content in the total non-volatile components of the phosphor paint to 25 vol% or more, the amount of curable resin components is relatively reduced. This reduces the difference in thermal expansion coefficient between the phosphor layer and the substrate on which the phosphor layer is formed. As a result, cracks are thought to be less likely to occur in the phosphor layer.

[0040] By having a high content of phosphor particles in the total non-volatile components of the phosphor paint, it is possible to sufficiently convert the light emitted from the light-emitting element into fluorescence even when the phosphor layer is thin, and to significantly change the color temperature of the light emitted from the light-emitting element.

[0041] On the other hand, from the viewpoint of preventing the phosphor particles from falling off from the formed phosphor layer, the content of the phosphor particles in the total non-volatile components of the phosphor coating material is preferably 60 vol % or less.

[0042] (Curable Resin Component) The phosphor coating material of this embodiment contains a curable resin component. In this specification, the term "curable resin component" refers not only to (1) a resin (polymer) component that has the property of being cured by the action of heat, light, etc., but also to (2) a component that is a monomer or oligomer before forming a coating film, but that can be polymerized by the action of heat, light, etc. to form a resin (polymer) after forming a coating film. In relation to the above, in this specification, in addition to polymers, monomers, or oligomers, polymerization initiators and curing agents are also included in the term "curable resin component."

[0043] When the curable resin component comprises a resin, a monomer, or an oligomer, it is typically organic, i.e., the curable resin component typically comprises an organic resin, an organic monomer, or an organic oligomer.

[0044] The curable resin component preferably contains a thermosetting resin component, which allows for the production of a highly durable lighting device. Of course, depending on the purpose and application, the curable resin component may also contain a thermoplastic resin.

[0045] The curable resin component preferably contains one or more selected from the group consisting of silicone resins and (meth)acrylate monomers. Among them, silicone resins (resins having siloxane bonds in the main skeleton) are preferred from the viewpoints of heat resistance, durability, etc.

[0046] The curable resin component preferably contains a silicone resin having phenyl and / or methyl groups. Such silicone resins are preferred in terms of compatibility with other components, solvent solubility, coatability, heat resistance, durability, etc. The phenyl:methyl ratio in this resin is, for example, about 0.3:1 to 1.5:1.

[0047] The curable resin component may contain reactive groups, which allows the curable resin component to cure by itself. As an example, the curable resin component preferably contains a silicone resin containing silanol groups (—Si—OH). This allows a condensation reaction of the silanol groups to occur during coating film formation, resulting in a cured coating film. The silanol content (OH wt %) of the silicone resin containing silanol groups (—Si—OH) is, for example, 0.1 mass % or more and 5 mass % or less. As another example, the curable resin component may be one that cures through a hydrosilylation reaction between a vinyl group-containing polymer and a Si—H group-containing silicone polymer (addition reaction type).

[0048] The weight-average molecular weight of the resin contained in the curable resin component is not particularly limited. Resins of any weight-average molecular weight can be contained as long as they can form a coating film as a coating material. For example, the weight-average molecular weight of the resin contained in the curable resin component is usually 1,000 or more and 1,000,000 or less, preferably 1,000 or more and 500,000 or less. When a commercially available product is used as the resin contained in the curable resin component, catalog data can be used as the weight-average molecular weight of the resin. When the weight-average molecular weight is unknown from the catalog, it can be determined, for example, by gel permeation chromatography (GPC) measurement using polyethylene as a standard substance.

[0049] Commercially available products may be used as the resin contained in the curable resin component. Commercially available silicone resins can be obtained, for example, from Dow Corning Toray Co., Ltd., Shin-Etsu Chemical Co., Ltd. Examples include RSN-0409, RSN-0431, RSN-0804, RSN-0805, RSN-0806, RSN-0808, and RSN-0840 (manufactured by Dow Corning Toray Co., Ltd.), and KF-8010, X-22-161A, KF-105, X-22-163A, X-22-169AS, KF-6001, KF-2200, X-22-164A, X-22-162C, X-22-167C, and X-22-173BX (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0050] As described above, the curable resin component may contain a monomer or oligomer instead of a resin. For example, the curable resin component preferably contains a (meth)acrylate monomer. The (meth)acrylate monomer may be monofunctional or polyfunctional. The (meth)acrylate monomer preferably has two to six (meth)acrylic structures in one molecule.

[0051] The curable resin component preferably contains a polymerization initiator together with the monomer or oligomer. For example, when the curable resin component contains a (meth)acrylate monomer, it is preferably used in combination with a radical polymerization initiator. The radical polymerization initiator generates radicals when exposed to heat or actinic rays.

[0052] The curable resin component may be any component known in the coating field, such as the silicone resin described above or a combination of a (meth)acrylate monomer and a polymerization initiator. The curable resin component may be, for example, (i) a urethane-based component containing a polyol and a polyisocyanate, or (ii) an epoxy-based component.

[0053] Examples of the polyol (i) include (meth)acrylic polyol, polyester polyol, polyether polyol, epoxy polyol, polyolefin polyol, fluorine-containing polyol, polycaprolactone polyol, polycaprolactam polyol, and polycarbonate polyol.

[0054] The polyisocyanate (i) is preferably di- to hexa-functional, more preferably di- to tetra-functional. Specific examples include aliphatic diisocyanates, cycloaliphatic diisocyanates, isocyanurate and biuret adducts, which are polymers of isocyanate compounds, and adducts of isocyanate compounds with polyhydric alcohols or low-molecular-weight polyester resins. Known polyisocyanates include biuret, isocyanurate, adduct, and allophanate types. Any of these can be used.

[0055] The polyisocyanate (i) may be a so-called blocked isocyanate. In other words, some or all of the isocyanate groups of the polyisocyanate may be in the form of blocked isocyanate groups blocked with protecting groups. For example, blocked isocyanate groups are formed by blocking the isocyanate groups with active hydrogen compounds such as alcohols, phenols, lactams, oximes, and active methylene compounds.

[0056] Examples of commercially available polyisocyanates include the Duranate (trade name) series manufactured by Asahi Kasei Corporation, the Takenate (trade name) series manufactured by Mitsui Chemicals, Inc., and the Desmodur (trade name) series manufactured by Sumika Bayer Urethane Co., Ltd.

[0057] The epoxy-based curable resin component (ii) typically contains an epoxy resin and a curing agent. Examples of the epoxy resin include bisphenol A epoxy resin, halogenated bisphenol A epoxy resin, novolac epoxy resin, polyglycol epoxy resin, bisphenol F epoxy resin, epoxidized oil, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether. Examples of the curing agent typically include polyamines such as polyvalent amines, amine adducts, and polyamides, as well as acid anhydrides.

[0058] The phosphor coating material of this embodiment may contain only one type of curable resin component, or may contain two or more types. The amount of the curable resin component in the phosphor coating material of this embodiment is preferably 40 vol% to 65 vol%, more preferably 45 vol% to 60 vol%, of the total non-volatile components.

[0059] (Flow Adjuster) The phosphor coating material of the present embodiment preferably contains a flow adjuster, which may enable adjustment of viscosity, flow characteristics (e.g., thixotropy) of the coating material, and application properties.

[0060] Examples of the flowability modifier include silica particles such as hydrophobic silica and hydrophilic silica, and aluminum oxide. Fumed silica is particularly preferred. Examples of commercially available flowability modifiers include AEROSIL 130, AEROSIL 200, AEROSIL 300, AEROSIL R-972, AEROSIL R-812, AEROSIL R-812S, Aluminum Oxide C (manufactured by Nippon Aerosil Co., Ltd.; AEROSIL is a registered trademark), and Carplex FPS-1 (manufactured by DSL Corporation; product name).

[0061] When the phosphor coating material of this embodiment contains a flowability modifier, it may contain only one type of flowability modifier, or it may contain two or more types of flowability modifiers. When the phosphor coating material of this embodiment contains a flowability modifier, the amount thereof is, for example, 10 vol% or less, preferably 1 vol% or more and 5 vol% or less, based on the total non-volatile components. On a mass basis rather than a volume basis, the amount of the flowability modifier is, for example, 5 mass% or less, preferably 0.1 mass% or more and 5 mass% or less, based on the total non-volatile components.

[0062] (Solvent) The phosphor coating material of this embodiment preferably contains a solvent. This allows for the production of a phosphor coating material with good coatability. The solvent contains water and / or an organic solvent. Examples of organic solvents include hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents.

[0063] Preferred organic solvents include alcohol-based solvents. Specific examples include methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-butanol, and t-butanol. Also preferred are ether bond-containing alcohols such as butyl carbitol (diethylene glycol monobutyl ether) and ethyl carbitol (diethylene glycol monoethyl ether). These solvents are particularly preferred when using a silicone resin, as they can dissolve / disperse the silicone resin well and allow the preparation of a phosphor coating material with excellent coatability.

[0064] The solvent preferably contains an aromatic hydrocarbon solvent. In particular, when a silicone resin is used, the use of an aromatic hydrocarbon solvent in combination with the silicone resin makes it easier to prepare a phosphor coating material with a good balance of various properties. Examples of aromatic hydrocarbon solvents include toluene and xylene.

[0065] When a solvent is used, only one type of solvent may be used, or two or more types of solvents may be used in combination. For example, the above-mentioned alcohol-based solvent and aromatic hydrocarbon solvent may be used in combination. When solvents are used in combination, it is preferable that each solvent be present in an amount of at least 1 mass% of the total amount of solvent in order to fully obtain the effect of the combination. When the phosphor coating material of this embodiment contains a solvent, it is preferable that the solvent is contained in an amount such that the non-volatile component concentration is 90 mass% or less. However, the non-volatile component concentration is not limited to this, and the amount may be adjusted appropriately as long as a coating film can be formed.

[0066] (Other Components) The phosphor coating material of this embodiment may contain other components in addition to those described above, such as an anti-rust pigment, an extender pigment, a surface conditioner, a wax, an antifoaming agent, a dispersant, an ultraviolet absorber, a light stabilizer, an antioxidant, a leveling agent, an anti-wrinkling agent, a plasticizer, and a charge control agent.

[0067] (Viscosity) As described above, the viscosity of the phosphor coating material of this embodiment measured at 25°C and 20 rpm using a Brookfield viscometer is 60 dPa·s or more and 450 dPa·s or less. The viscosity is preferably 80 dPa·s or more and 350 dPa·s or less, and more preferably 90 dPa·s or more and 320 dPa·s or less. By setting the viscosity in this range, a phosphor layer of appropriate thickness can be formed, particularly by screen printing.

[0068] (Form of Paint) The phosphor paint of this embodiment may be a one-component type or a multi-component type consisting of two or more components. Specifically, the film-forming resin composition of this embodiment can be supplied as a one-component composition in which all necessary components are uniformly mixed or dispersed. Alternatively, the film-forming resin composition of this embodiment may be supplied as a two-component type (two-component kit) consisting of component A containing some of the components and component B containing the remaining components. From the viewpoint of storage stability before coating, it may be preferable to use a multi-component phosphor paint. When the phosphor paint of this embodiment is a multi-component type, the respective components are uniformly mixed to obtain a paint for coating immediately before forming a coating film. The viscosity of this paint for coating is set to be 60 dPa·s or more and 450 dPa·s or less.

[0069] <Coating Film, Phosphor Substrate, and Lighting Device> The above-described phosphor coating material can be used to form a coating film containing phosphor particles. The above-described phosphor coating material can also be used to manufacture a phosphor substrate having a coating film containing phosphor particles. Furthermore, the above-described phosphor coating material can be used to manufacture a lighting device having an insulating substrate, a coating film formed on one side of the insulating substrate using the above-described phosphor coating material, and a light-emitting element (such as an LED element) installed on the surface of the coating film opposite the insulating substrate.

[0070] The coating film, the phosphor substrate, and the lighting device will be described below while illustrating an example of the configuration of the lighting device.

[0071] Fig. 1 is a schematic cross-sectional view of a lighting device. In the lighting device of Fig. 1, a fluorescent coating film 26 is provided on one surface of an insulating substrate 20. A first copper foil 22 and a white layer 24 are provided between the insulating substrate 20 and the fluorescent coating film 26, in this order from the insulating substrate 20 side. A portion of the first copper foil 22 is removed by etching, and functions as a copper circuit (copper wiring).

[0072] A surface-mounted LED element 28 (light-emitting element) is disposed on the surface of the fluorescent coating 26 opposite the insulating substrate 20. The surface-mounted LED element 28 is electrically connected to the first copper foil 22 by solder 30 provided to penetrate the white layer 24 and the fluorescent coating 26. Electricity is supplied to the surface-mounted LED element 28 via the first copper foil 22 and the solder 30, causing the surface-mounted LED element 28 to emit light. To enhance the luminous efficiency of the phosphor coating, a white layer 32 (more specifically, a white resin layer 32) is preferably provided below the surface-mounted LED element 28. This prevents light from escaping (transmitting). Furthermore, at least a portion of the light incident from the fluorescent coating 26 is reflected at the interface between the white layer 32 and the fluorescent coating 26. The lighting device of FIG. 1 may include multiple surface-mounted LED elements 28.

[0073] A second copper foil 22B can be provided on the other surface (the surface opposite to the surface on which the fluorescent coating film 26 is provided) of the insulating substrate 20. By providing the first copper foil 22 on one surface of the insulating substrate 20 and the second copper foil 22B on the other surface, a balance of forces is achieved on both surfaces of the insulating substrate 20, and, for example, the occurrence of warping can be suppressed.

[0074] The material of the insulating substrate 20 is not particularly limited as long as it is usable for PWBs (printed wiring boards). Examples of materials that can be used include polyimide resin, silicone resin, (meth)acrylic resin, urea resin, epoxy resin, fluororesin, glass, and metal (aluminum, copper, iron, stainless steel, etc.). From the standpoint of heat resistance, polyimide resin, silicone resin, glass, and metal (such as a so-called "metal substrate" using aluminum or copper as the base metal and an insulating layer) are preferably used. It is also preferable to use commercially available materials such as "bonding sheets." The thickness of the insulating substrate 20 is not particularly limited as long as it is usable for lighting fixtures. For example, it is 50 μm or more and 1000 μm or less, specifically 50 μm or more and 500 μm or less.

[0075] The white layer 24 and the white layer 32 can be formed using, for example, a white paint. The composition and properties of the white paint are not particularly limited as long as the white layer 24 can be formed. For example, a paint composition using a white pigment instead of the phosphor particles in the above-mentioned paint composition can be used. The application method can be the same as that for the fluorescent coating film 26 described below. Examples of the white pigment include known pigments such as titanium oxide. Inorganic pigments are preferred from the standpoint of stability, etc. The thickness of the white layer 24 is, for example, 10 μm or more and 500 μm or less, specifically 20 μm or more and 400 μm or less.

[0076] The fluorescent coating 26 can be formed by applying the coating composition described above. The fluorescent coating 26 converts light emitted from the light-emitting element into light of a different wavelength / color temperature. The application method is not particularly limited. A preferred method is a printing method such as screen printing. In this embodiment, the viscosity of the coating composition is 60 dPa·s or higher and 450 dPa·s or lower, so that a uniform fluorescent coating 26 with an appropriate thickness can be formed by applying the screen printing method. Of course, other application methods may also be used. For example, the coating composition may be applied using various coaters known in the coatings field. After application, drying and curing treatments are preferably performed. The drying conditions are, for example, 60°C or higher and 100°C or lower for 15 minutes or longer and 60 minutes or shorter. The curing conditions are, for example, 100°C or higher and 200°C or lower for 30 minutes or longer and 240 minutes or shorter.

[0077] The amount of coating composition applied is adjusted so that the thickness of fluorescent coating 26 in the finished lighting device is preferably 150 μm or less, more preferably 30 μm to 100 μm, and even more preferably 30 μm to 80 μm. When the content of phosphor particles in the coating composition is 25 vol% or more, preferably 30 vol% or more, and more preferably 35 vol% or more, even if the thickness of fluorescent coating 26 is 150 μm or less, light emitted from surface-mounted LED elements 28 can be sufficiently converted into fluorescence, and the light emitted from surface-mounted LED elements 28 is less likely to pass through the phosphor layer.

[0078] Incidentally, holes through which the solder 30 passes can be formed by mechanically drilling the cured white layer 24 and / or the fluorescent coating film 26. The subsequent connection between the surface-mounted LED element 28 (light-emitting element) and the first copper foil 22 with the solder 30 can be performed by any known method.

[0079] Examples of the surface-mounted LED element 28 (light-emitting element) include a CSP, an SMD (Surface Mount Device), and a flip-chip element. In this embodiment, the light-emitting element is preferably a CSP. The light-emitting element typically emits blue light.

[0080] In this embodiment, it is particularly preferable that the light-emitting element does not include a reflector. Specifically, some known surface-mounted LED elements (light-emitting elements) are equipped with a reflector, as shown in FIG. 2A, so that light from the LED chip does not leak sideways or downward. However, in this embodiment, it is preferable that the surface-mounted LED element 28 (light-emitting element) does not include a reflector, as shown in FIG. 2B. By using a light-emitting element without a reflector, light from the LED chip leaks sideways or downward. The leaked light then strikes the portion of the fluorescent coating 26 indicated by α, causing the portion α to emit light. This further reduces the problems of glare and multiple shadows.

[0081] In the light-emitting device of FIG. 2A , the semiconductor light-emitting element 100 is disposed in a package-like portion 108 formed by a substrate 102 and a reflector (housing) 104, and the package-like portion 108 is filled with a sealing member 110 (light-transmitting resin). The substrate 102 may include wiring 112. In FIG. 2B , the same elements as in FIG. 2A are denoted by the same reference numerals. The light-emitting element of FIG. 2B does not use a housing (reflector). After mounting the semiconductor light-emitting element 100 as shown in the figure, the sealing member 110 can be formed by molding using a desired mold. Alternatively, the sealing member 110 may be prepared in advance in a desired shape and then adhered to the substrate 102 so as to cover the semiconductor light-emitting element 100.

[0082] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0083] The embodiments of the present invention will be described in detail based on Examples and Comparative Examples. However, it should be noted that the present invention is not limited to the Examples.

[0084] <Materials> The following were prepared. (Phosphor particles) CASN-1: CASN-based phosphor manufactured by Denka Co., Ltd., product number RE-650YMDB, D ５０= 15.7 μm CASN-2: CASN-based phosphor manufactured by Denka Co., Ltd., product number RE-Sample 650SD4, D ５０ = 3.2 μm YAG phosphor (used in Comparative Example 2): D ５０ = 8.5 μm

[0085] The particle size distribution of the phosphor particles (D ５０ ) was measured as follows. (1) Dispersion Treatment by Ultrasonic Waves 30 mg of phosphor particles were uniformly dispersed in 100 mL of aqueous sodium hexametaphosphate solution adjusted to 0.2% by mass, and the resulting dispersion was placed in a cylindrical container with a bottom radius of 2.75 cm. Then, a cylindrical tip with a radius of 10 mm of an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., US-150E) was immersed in the dispersion to a depth of 1.0 cm or more, and ultrasonic waves were irradiated for 3 minutes at a frequency of 19.5 kHz and an output of 150 W. (2) Measurement of Particle Size Distribution The dispersion prepared as in (1) above was measured using a laser diffraction scattering particle size distribution analyzer (manufactured by Microtrackbell Co., Ltd., MT3300EXII) to determine the particle size distribution. Furthermore, D was calculated from the particle size distribution data. ５０ asked for.

[0086] (Curable resin component) Silicone resin "RSN-0805" from Dow Corning Toray Co., Ltd. (silanol group-containing, silanol content (OH weight) 1%, silicon dioxide content 48% by weight, phenyl:methyl ratio = 1.1:1, weight average molecular weight 200 to 300 × 10 ３ , xylene included, resin solids content 50% by weight

[0087] (Flow adjuster) AEROSIL 200 fumed silica from Nippon Aerosil Co., Ltd.

[0088] (Solvent) Butyl carbitol

[0089] <Preparation of Coating Composition> First, a curable resin component (silicone resin) and a solvent were mixed to obtain a uniform solution. Then, phosphor particles and a flowability modifier (Example 3 only) were added to the solution and uniformly mixed and dispersed to obtain a coating composition. The viscosity of the resulting coating composition was measured using a No. 4 rotor of a Brookfield viscometer at 25°C and 20 rpm.

[0090] <Formation of Coating Film (Phosphor Layer) / Fabrication of Lighting Device> Using the coating composition prepared above, a lighting device with the structure described in Figure 1 (multiple CSPs aligned at regular intervals on a phosphor layer) was fabricated. The fabrication procedure is briefly described below. (1) A bonding sheet CS-3305A manufactured by Risho Kogyo Co., Ltd., with copper foil laminated on both sides, was prepared as the insulating substrate material. The copper foil was etched to form a copper circuit on the first copper foil. (2) A 40 μm-thick white layer was formed on the first copper foil using white paint (a silicone binder mixed with titanium oxide / alumina at 50 vol%). (3) The above phosphor paint was printed (film formation) on the white layer by screen printing using an 86-mesh screen, pre-cured at 80°C for 30 minutes, and then post-cured (mainly cured) at 180°C for 60 minutes. This formed a phosphor layer. The target thickness of the phosphor layer was 50 μm. (4) Holes were drilled in parts of the white layer and phosphor layer to provide soldering holes. A commercially available surface-mount LED element, a CSP (WICOP SZ8-Y15-WW-C8, manufactured by Seoul Semiconductor, reflector-less, color temperature 2200-2300 K), was then electrically connected to the first copper foil (copper circuit) using solder.

[0091] <Evaluation: Printability> In the above (3), the printability was evaluated as good (○) when the printed phosphor paint did not flow before pre-curing and a uniform phosphor layer with a thickness of 45 to 55 μm was formed, the printability was evaluated as fair (△) when the printed phosphor paint flowed slightly before pre-curing but a uniform phosphor layer with a thickness of 45 to 55 μm was formed, and the printability was evaluated as poor (×) when a phosphor layer with a sufficient thickness could not be formed or unevenness occurred in the film.

[0092] <Evaluation: Appearance of Phosphor Layer> The appearance of the phosphor layer formed in (3) above was observed. In Table 2 below, cases where no abnormality that could be a practical problem was observed were recorded as "no abnormality," and cases where an abnormality that could be a practical problem was observed were recorded as "no abnormality."

[0093] <Evaluation: Durability of Phosphor Layer, etc.> For those samples that were found to be "normal" in the above appearance evaluation of the phosphor layer, the following tests were carried out for the items in Table 1. Those samples that met the pass criteria for all the items in Table 1 were marked "Pass" in Table 2.

[0094]

[0095] <Evaluation: Color Temperature Conversion> A current was passed through the lighting device prepared above, causing the lighting device to emit light. The color temperature of the light emitted from the lighting device was measured using a total luminous flux measurement system (equipped with an integrating sphere) manufactured by Otsuka Electronics Co., Ltd. If the measured color temperature was 2000 to 2100 K and the color temperature was converted by at least 100 K from the color temperature of the CSP itself (2200 to 2300 K), the color temperature conversion was evaluated as good (○). On the other hand, if the measured color temperature was 2100 to 2200 K and the color temperature conversion remained within 100 K, the color temperature conversion was evaluated as insufficient (×). Note that this evaluation was not performed in Comparative Example 2, where the properties of the phosphor layer were abnormal.

[0096] The composition of the phosphor paint and the evaluation results are summarized in the table below.

[0097]

[0098] By using a phosphor coating containing phosphor particles and a curable resin component, with a viscosity of 60 dPa·s or more and 450 dPa·s or less, measured at 25°C and 20 rpm using a Brookfield viscometer, a phosphor layer could be formed at a relatively low temperature of around 180°C, without the need for high-temperature sintering required for glass binders. Furthermore, the appearance and durability of the formed phosphor layer were excellent. Furthermore, the formed phosphor layer significantly changed the color temperature of the light emitted from the CSP.

[0099] This application claims priority based on Japanese Patent Application No. 2020-134392, filed on August 7, 2020, the disclosure of which is incorporated herein in its entirety.

[0100] 20 insulating substrate 22 first copper foil 22B second copper foil 24 white layer 26 fluorescent coating film 28 surface-mounted LED element 30 solder 32 white layer (white resin layer) 100 semiconductor light-emitting element 102 substrate 104 reflector (housing) 108 package-shaped portion 110 sealing member 112 wiring

Claims

1. A phosphor paint containing phosphor particles and a curable resin component, the viscosity of which, measured at 25°C and 20 rpm using a B-type viscometer, is 60 dPa·s or more and 450 dPa·s or less.

2. A phosphor coating material according to claim 1, wherein the curable resin component contains a thermosetting resin component.

3. A phosphor coating material according to claim 1 or 2, wherein the curable resin component contains a silicone resin.

4. A phosphor coating material according to any one of claims 1 to 3, wherein the curable resin component contains a silicone resin having a phenyl group and a methyl group.

5. A phosphor coating according to any one of claims 1 to 4, wherein the curable resin component contains a silicone resin containing a silanol group.

6. The phosphor coating material according to any one of claims 1 to 5, wherein the median diameter D of the phosphor particles is ５０ is a phosphor paint having a thickness of 1 μm or more and 20 μm or less.

7. A phosphor coating material according to any one of claims 1 to 6, wherein two or more maxima are observed in the particle size distribution curve of the phosphor particles.

8. A phosphor paint according to claim 7, wherein a particle size distribution curve of the phosphor particles has a maximum in both a region of particle size of 1 μm or more and 6 μm or less and a region of particle size of 10 μm or more and 25 μm or less.

9. The phosphor coating material according to any one of claims 1 to 8, wherein the phosphor particles are selected from the group consisting of CASN phosphor, SCASN phosphor, La ３ S ６ N １１ Sr based phosphor ２ S ５ N ８ Ba-based phosphor ２ S ５ N ８ The phosphor coating material contains one or more phosphors selected from the group consisting of ZnO-based phosphors, α-type Sialon-based phosphors, β-type Sialon-based phosphors, LuAG-based phosphors and YAG-based phosphors.

10. A phosphor coating material according to any one of claims 1 to 9, which contains a flowability adjusting agent.

11. A phosphor coating material according to any one of claims 1 to 10, further comprising a solvent.

12. The phosphor paint according to claim 11, wherein the solvent contains an aromatic hydrocarbon solvent.

13. A coating film formed from the phosphor coating material according to any one of claims 1 to 12.

14. The coating according to claim 13, having a thickness of 150 μm or less.

15. A phosphor substrate provided with the coating film according to claim 13 or 14.

16. A lighting device comprising an insulating substrate, a coating film formed on one side of the insulating substrate using the phosphor paint according to any one of claims 1 to 12, and a light-emitting element installed on the surface of the coating film opposite the insulating substrate.

17. A lighting device according to claim 16, comprising a plurality of said light emitting elements.

18. A lighting device according to claim 16 or 17, wherein the light emitting element does not include a reflector.

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