Phosphorescent paints, coatings, phosphorescent substrates, and lighting devices

Abstract

A fluorescent coating material according to the present invention comprises fluorescent particles and a curable resin component. Fluorescent particle content in all non-volatile components of the fluorescent coating material is 25-60 vol%. Using this fluorescent coating material, it is possible to produce a coating film (fluorescent layer), fluorescent substrate, and illumination device.

Description

[Technical Field]

[0001] The present invention relates to phosphor coatings, coating films, phosphor substrates, and lighting devices. [Background technology]

[0002] Various developments are underway regarding lighting devices using LEDs (Light Emitting Devices). These include not only the development of the LEDs themselves, but also the development of mounting boards that incorporate them.

[0003] For example, in Example 2 of Patent Document 1, it is described that (i) a glass binder coating containing 30 vol% phosphor was applied to the surface of a glass substrate to form a phosphor layer with a thickness of 200 μm, (ii) a mounting substrate for LED lighting was obtained by bonding a plurality of CSPs to the glass substrate, and (iii) when the mounting substrate was energized, problems of glare and multiple shadows were reduced despite the emission of light from multiple CSPs. (CSP stands for Chip Scale Package or Chip Size Package, and it is a package-less design in which an LED chip is encased in phosphor resin, consisting only of the LED chip and phosphor resin.) [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2019 / 093339 [Overview of the project] [Problems that the invention aims to solve]

[0005] In Example 2 of Patent Document 1, a phosphor layer with a thickness of 200 μm is formed on a glass substrate using a "glass binder paint" containing a phosphor. However, in order to fully cure the glass binder paint, a sintering process at a high temperature is usually required, so there is room for improvement in terms of the simplicity of forming the phosphor layer. In addition, the casing / substrate for applying the glass binder paint is also subject to restrictions such as heat resistance and optimization of the expansion coefficient.

[0006] The present invention has been made in view of such circumstances. One of the objects of the present invention is to provide a material capable of easily forming a phosphor layer.

Means for Solving the Problems

[0008] According to the present invention, a phosphor paint containing phosphor particles and a curable resin component, where the content of the phosphor particles in all non-volatile components is 25 vol% or more and 60 vol% or less is provided.

[0009] Also, according to the present invention, a coating film formed by the above phosphor paint is provided.

[0010] Also, according to the present invention, a phosphor substrate provided with the above coating film is provided.

[0011] Also, according to the present invention, a lighting device including an insulating substrate, a coating film provided on one side of the insulating substrate by the above phosphor paint, and a light-emitting element installed on the surface of the coating film opposite to the insulating substrate is provided.

Effects of the Invention

[0012] ​​​​By using the phosphor coating of the present invention, a phosphor layer can be easily formed. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view of a lighting device. [Figure 2] This diagram illustrates LED chips without reflectors and LED chips with reflectors. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described in detail below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and explanations are omitted where appropriate. All drawings are for illustrative purposes only. The shapes and dimensional ratios of the components shown in the drawings do not necessarily correspond to actual items.

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

[0016] <Fluorescent paint> The phosphor coating of this embodiment comprises phosphor particles and a curable resin component. The content of phosphor particles in the total nonvolatile components of the phosphor coating of this embodiment is 25 vol% or more and 60 vol% or less.

[0017] The phosphor coating of this embodiment contains a curable "resin component" instead of a glass binder. As a result, using the phosphor coating of this embodiment, a phosphor layer can be formed relatively easily without requiring sintering at high temperatures.

[0018] The fact that high-temperature sintering is not required means that the types of phosphors that can be used are not limited. Specifically, when trying to obtain a cured film with a glass binder, firing at a high temperature of approximately 600°C is required. When such high temperatures are required, it is necessary to select a phosphor that can withstand high temperatures, which may limit the types of phosphors that can be used. In addition, peeling is likely to occur when cooling from high temperatures. However, by preparing a phosphor coating using a curable resin component, it is possible to form a phosphor layer that is less prone to peeling without requiring high temperatures of approximately 600°C. The fact that high-temperature sintering is not required also has the advantage of reducing the constraints on optimizing the heat resistance and thermal expansion coefficient of the housing / substrate to which the paint is applied or printed.

[0019] Furthermore, by using a curable resin component, it is easy to form a moderately thin phosphor layer by coating or printing. This is particularly effective when the phosphor particle content in the phosphor coating is high. The inventors have set the content of phosphor particles in the total non-volatile components of the phosphor coating to 25 vol% or more so that the light emitted from the light-emitting element can be sufficiently converted into fluorescence, and so that the light emitted from the light-emitting element does not pass through the phosphor layer.

[0020] By setting the phosphor particle content in the total non-volatile components of the phosphor coating to 25 vol% or more, other advantages can be obtained besides the ability to sufficiently convert light emitted from the light-emitting element into fluorescence. One example of such benefits is improved coating or printability. A moderately high concentration of phosphor particles in the phosphor coating makes the coating moderately less fluid, which in turn makes it easier to form a phosphor layer of an appropriate thickness.

[0021] Furthermore, by ensuring that the phosphorescent particles make up 25 vol% or more of the total non-volatile components of the phosphorescent paint, there is the added benefit of making the phosphorescent layer less prone to cracking. Based on general knowledge, one of the causes of crack formation is thought to be the difference in thermal expansion coefficients between the phosphor layer and the substrate on which the phosphor layer is attached. By increasing the content of phosphor particles in the total non-volatile components of the phosphor coating to 25 vol% or more, the curable resin component is relatively reduced. As a result, the difference between the thermal expansion coefficient of the phosphor layer and the thermal expansion coefficient of the substrate on which the phosphor layer is attached becomes smaller. Consequently, it is thought that crack formation in the phosphor layer becomes less likely.

[0022] The content of phosphor particles in the total non-volatile components of the phosphor coating is preferably 30 vol% or more, more preferably 35 vol% or more. This allows for sufficient conversion of light emitted from a light-emitting element into fluorescence, even when the phosphor layer is thin, and enables a significant change in the color temperature of the light emitted from the light-emitting element.

[0023] On the other hand, if the content of phosphor particles in the total non-volatile components of the phosphor paint is too high, the phosphor particles tend to detach from the formed phosphor layer. Therefore, the content of phosphor particles in the total non-volatile components of the phosphor paint is kept at 60 vol% or less.

[0024] The following describes the components and physical properties of the phosphorescent coating of this embodiment.

[0025] (Phosphor particles) The phosphor coating of this embodiment contains phosphor particles. The phosphor particles can be any particles that emit fluorescence when exposed to light emitted from a light-emitting element. Depending on the desired color and color temperature, only one type of specific phosphor particle may be used, or two or more types of phosphor particles may be used in combination.

[0026] Examples of phosphor particles include CASN-based phosphors, SCASN-based phosphors, and La3Si6N 11One or more selected from the group consisting of a nitride phosphor, a Sr2Si5N8-based phosphor, a Ba2Si5N8-based phosphor, an α-sialon-based phosphor, a β-sialon-based phosphor, a LuAG-based phosphor, and a YAG-based phosphor can be mentioned. These phosphors usually contain activating elements such as Eu and Ce.

[0027] The CASN-based phosphor (a kind of nitride phosphor) preferably contains Eu. The CASN-based phosphor is, for example, of the formula CaAlSiN3:Eu 2+ represented by, with Eu 2+ as an activator, and is a red phosphor having a crystal composed of an alkaline earth silicon nitride as a matrix. In the definition of the CASN-based phosphor containing Eu in this specification, the SCASN-based phosphor containing Eu is excluded.

[0028] The SCASN-based phosphor (a kind of nitride phosphor) preferably contains Eu. The SCASN-based phosphor is, for example, of the formula (Sr,Ca)AlSiN3:Eu 2+ ​​​​​​​​​​​​​​​​​​​​​​​​​​The α-sialon-based phosphor preferably contains Eu. The α-sialon containing Eu is, for example, 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 at least one element containing at least Ca selected from the group consisting of Li, Mg, Ca, Y, and lanthanide elements (excluding La and Ce). When the valence of M is a, ax + २y = m, where 0 < x ≤ 1.5, 0.3 ≤ m < 4.5, and 0 < n < 2.25.

[0033] The β-sialon-based phosphor preferably contains Eu. The β-sialon containing Eu is, for example, represented by the general formula Si 6-z Al z O z N 8-z :Eu 2+ (0 < Z ≤ 4.2), and is a phosphor composed of β-sialon in which Eu 2+ is solid-solved. 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 4.2 or less, and from the viewpoint of further improving the emission intensity of the β-sialon, it is preferably 0.005 or more and 1.0 or less. Also, the europium content is preferably 0.1% by mass or more and 2.0% by mass or less.

[0034] The LuAG-based phosphor usually means a lutetium aluminum garnet crystal. Considering the application to an illumination device, LuAG is preferably a LuAG:Ce phosphor. More specifically, LuAG can be represented by the composition formula of Lu3Al5O 12 :Ce, but the composition of LuAG does not necessarily have to follow stoichiometry.

[0035] The YAG-based phosphor usually means a yttrium aluminum garnet crystal. Considering the application to an illumination device, the YAG-based phosphor is preferably activated with Ce. More specifically, the YAG-based phosphor is Y3Al5O 12Although it can be represented by the empirical formula :Ce, the composition of YAG-based phosphors does not necessarily have to follow stoichiometry.

[0036] Commercially available phosphor particles may be used. Examples of commercially available phosphor particles include Aronbright® from Denka Co., Ltd. Others, such as Mitsubishi Chemical Corporation, also offer commercially available phosphor particles.

[0037] Median diameter D of phosphor particles 50 The median diameter D is preferably 1 μm to 20 μm, more preferably 5 μm to 15 μm. 50 By properly adjusting these properties, for example, the fluidity of the phosphorescent coating can be adjusted, making it easier to form a thin and uniform coating film.

[0038] In the particle size distribution curve of the phosphor particles, it is preferable to observe two or more maxima. Specifically, it is preferable to observe maxima in both the region of particle size between 1 μm and 6 μm, and the region of particle size between 10 μm and 25 μm. Observing two or more maxima means that the phosphor particles include both large and small particles. Since the small particles fill the "gaps" between the large particles, it is easier to increase the phosphor particle content compared to using only large particles. Furthermore, even if the phosphor particle content is increased, it is easier to maintain the various physical properties of the paint. In addition, when formed into a coating film, light emitted from the light-emitting element becomes less permeable.

[0039] Median diameter D of phosphor particles 50 The particle size distribution curve can be adjusted by methods such as improving the preparation method of the phosphor particles, appropriately grinding the phosphor particles, or appropriately mixing two or more phosphor particles with different particle sizes.

[0040] The particle size distribution curve of phosphor particles can be measured using a laser diffraction scattering particle size analyzer after the raw phosphor particles are dispersed in a dispersion medium using an ultrasonic homogenizer. From the obtained particle size distribution curve, the median diameter D can be determined. 50This can be determined. For details on distributed processing and measurement devices, please refer to the examples described later. Just to clarify, in this specification, median diameter D 50 The particle size distribution curve is measured on a volume basis.

[0041] The phosphor coating of this embodiment may contain only one type of phosphor particle, or it may contain two or more types. As mentioned above, the content of phosphor particles in the total nonvolatile components of the phosphor coating is 25 vol% to 60 vol%. Preferably, this content is 30 vol% to 60 vol%, more preferably 35 vol% to 60 vol%, and even more preferably 40 vol% to 50 vol%.

[0042] (curable resin component) The phosphor coating of this embodiment contains a curable resin component. In this specification, "curable resin component" includes not only (1) resin (polymer) components that have the property of hardening due to the action of heat, light, etc., but also (2) components that are monomers or oligomers before film formation, but can be increased in molecular weight to form a resin (polymer) after film formation due to the action of heat, light, etc. In connection with the above, in this specification, polymers, monomers, or oligomers, as well as polymerization initiators and curing agents, are also considered to be part of the "curable resin component."

[0043] When curable resin components include resins, monomers, or oligomers, these are usually organic. In other words, curable resin components typically include organic resins, organic monomers, or organic oligomers.

[0044] The curable resin component preferably includes a thermosetting resin component. This makes it possible to manufacture lighting devices with high durability. Of course, depending on the purpose and application, the curable resin component may also include a thermoplastic resin.

[0045] The curable resin component preferably includes one or more selected from the group consisting of silicone resins and (meth)acrylate monomers. Among these, silicone resins (resins having siloxane bonds as the main backbone) are preferred from the viewpoint of heat resistance and durability.

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

[0047] The curable resin component may contain reactive groups. This allows the curable resin component to cure on its own. 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 film formation, resulting in a cured coating. The silanol content (OH weight%) of the silicone resin containing silanol groups (-Si-OH) is, for example, 0.1% by mass or more and 5% by mass or less. As another example, the curable resin component may be one that hardens 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. It can contain resins of any weight-average molecular weight as long as it can form a coating film as a paint. As an example, the weight-average molecular weight of the resin contained in the curable resin component is usually between 1,000 and 1,000,000, preferably between 1,000 and 500,000. When using commercially available resins as the resin component of a curable resin, the weight-average molecular weight of the resin can be determined from the catalog data. If 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 the standard substance.

[0049] A commercially available resin may be used as the resin component included in the curable resin. Commercially available silicone resins can be obtained from companies such as Toray Dow Corning and Shin-Etsu Chemical Co., Ltd. Examples include RSN-0409, RSN-0431, RSN-0804, RSN-0805, RSN-0806, RSN-0808, RSN-0840 (manufactured by Toray Dow Corning), 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, X-22-173BX (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0050] As mentioned above, the curable resin component may include monomers or oligomers instead of resins. 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 2 to 6 (meth)acrylic structures in one molecule.

[0051] The curable resin component preferably contains a polymerization initiator along with monomers and oligomers. For example, if the curable resin component contains a (meth)acrylate monomer, it is preferable to use it in combination with a radical polymerization initiator. A radical polymerization initiator generates radicals when exposed to heat or active light.

[0052] The curable resin component can be any component known in the field of paints, in addition to the silicone resins and combinations of (meth)acrylate monomers and polymerization initiators mentioned above. The curable resin component may be, for example, (i) a urethane-based resin containing a polyol and a polyisocyanate, or (ii) an epoxy-based resin.

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

[0054] (i) The polyisocyanate can preferably be a bifunctional, more preferably bifunctional, polyisocyanate with 2 to 6 functions. Specifically, examples include aliphatic diisocyanates, cyclic aliphatic diisocyanates, isocyanurates and biuret adducts which are polymers of isocyanate compounds, and polyisocyanate compounds added to polyhydric alcohols or low molecular weight polyester resins. Biuret type, isocyanurate type, adduct type, and allophanate type polyisocyanates are also known. Any of these can be used.

[0055] (i) The polyisocyanate 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, which are blocked by a protecting group. For example, isocyanate groups are blocked by active hydrogen compounds such as alcohols, phenols, lactams, oximes, and active methylene compounds to form blocked isocyanate groups.

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

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

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

[0059] (Flow modifier) The phosphorescent coating of this embodiment preferably contains a fluidity modifier. This may allow for adjustment of the coating's flow characteristics and applicability.

[0060] Suitable fluidity modifiers include silica particles such as hydrophobic silica and hydrophilic silica, as well as aluminum oxide. Fumed silica is particularly preferred. Examples of commercially available fluidity 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, Inc., trade name).

[0061] If the phosphor coating of this embodiment contains a fluidity modifier, it may contain only one type of fluidity modifier, or it may contain two or more types of fluidity modifiers. If the phosphor coating of this embodiment contains a flow modifier, its amount is, for example, 10 vol% or less, preferably 1 vol% to 5 vol% of the total nonvolatile components. On a mass basis rather than a volume basis, the amount of the flow modifier is, for example, 5 mass% or less, preferably 0.1 mass% to 5 mass% of the total nonvolatile components.

[0062] (solvent) The phosphor coating of this embodiment preferably contains a solvent. This makes it possible to obtain a phosphor coating with good applicability. The solvent includes 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. Specifically, these include methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-butanol, and t-butanol. Ether-containing alcohols such as butyl carbitol (diethylene glycol monobutyl ether) and ethyl carbitol (diethylene glycol monoethyl ether) are also preferred. These are particularly preferred when using silicone resin as the resin, as they effectively dissolve and disperse the silicone resin, allowing for the preparation of a phosphorescent coating with good coatability.

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

[0065] When using solvents, one type of solvent may be used, or two or more solvents may be used in combination. For example, the above-mentioned alcohol-based solvent and aromatic hydrocarbon solvent may be used in combination. When using solvents in combination, it is preferable that each solvent be present in an amount of at least 1% by mass of the total solvent to obtain sufficient effects from the combination. When the phosphorescent coating of this embodiment contains a solvent, it is preferable to include the solvent in an amount such that the concentration of non-volatile components is 90% by mass or less. However, the concentration of non-volatile components is not limited to this, and the amount may be adjusted as appropriate as long as a coating film can be formed.

[0066] (Other ingredients) The phosphor coating of this embodiment may also contain other components besides those listed above. Examples of other components include rust-preventive pigments, extender pigments, surface modifiers, waxes, defoamers, dispersants, ultraviolet absorbers, light stabilizers, antioxidants, leveling agents, anti-corrosion agents, plasticizers, and static charge control agents.

[0067] (viscosity) The viscosity of the phosphor coating in this embodiment is preferably adjusted appropriately. Appropriate viscosity leads to improved coatability, easier formation of thin coating films, and other enhancements. Specifically, the viscosity of the phosphor coating, measured using a Type B viscometer at 25°C and a rotation speed of 20 rpm, is preferably 60. dPa·s Above 500 dPa·s or less, more preferably 80 dPa·s The viscosity is 400 dPa·s or less. This viscosity is particularly effective in improving film formation when using screen printing. When forming a coating by a method other than screen printing, the optimal viscosity may differ from the above numerical range.

[0068] (Form of paint) The phosphor coating of this embodiment may be a one-component type or a multi-component type with 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 (a two-component kit) consisting of liquid A containing some of the components and liquid B containing the remaining components. From the standpoint of storage stability before application, it is sometimes preferable to use a multi-component type of fluorescent coating. In the case where the phosphor coating of this embodiment is a multi-component type, the liquids are uniformly mixed immediately before forming the coating film to obtain a coating paint. In this coating paint, the content of phosphor particles in the total non-volatile components is 25 vol% or more and 50 vol% or less.

[0069] <Coating films, phosphor substrates, lighting devices> Using the above-mentioned phosphorescent paint, a coating film containing phosphorescent particles can be formed. Furthermore, a phosphor substrate having a coating film containing phosphor particles can be manufactured using the above-mentioned phosphor coating. Furthermore, using the above-mentioned phosphor paint, a lighting device can be manufactured comprising an insulating substrate, a coating film provided on one side of the insulating substrate using the above-mentioned phosphor paint, and a light-emitting element (such as an LED element) installed on the side of the coating film opposite to the insulating substrate.

[0070] The following describes the coating, phosphor substrate, and lighting device, illustrating an example of the lighting device configuration.

[0071] Figure 1 is a schematic cross-sectional view of a lighting device. In the lighting device shown in Figure 1, a fluorescent coating 26 is provided on one side of the insulating substrate 20. Between the insulating substrate 20 and the fluorescent coating 26, a first copper foil 22 and a white layer 24 are provided in 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-mount LED element 28 (light-emitting element) is installed on the side of the fluorescent coating 26 opposite to the insulating substrate 20. The surface-mount LED element 28 is electrically connected to the first copper foil 22 by solder 30 that penetrates the white layer 24 and the fluorescent coating 26. Electricity is supplied to the surface-mount LED element 28 via the first copper foil 22 and the solder 30, causing the surface-mount LED element 28 to emit light. From the viewpoint of improving the luminous efficiency of the phosphor coating, it is preferable to provide a white layer 32 (more specifically, a white resin layer 32) on the lower part of the surface-mount LED element 28. This suppresses light leakage (transmission). In addition, at least a portion of the light entering from the fluorescent coating 26 is reflected at the interface between the white layer 32 and the fluorescent coating 26. The lighting device shown in Figure 1 can be equipped with multiple surface-mount LED elements 28.

[0073] A second copper foil 22B can be provided on the other side of the insulating substrate 20 (the side opposite to the side on which the fluorescent coating 26 is provided). Having the first copper foil 22 on one side of the insulating substrate 20 and the second copper foil 22B on the other side balances the forces on both sides of the insulating substrate 20, which suppresses, for example, the occurrence of warping.

[0074] The material of the insulating substrate 20 is not particularly limited as long as it is suitable for use in printed circuit boards (PWBs). For example, polyimide resin, silicone resin, (meth)acrylic resin, urea resin, epoxy resin, fluororesin, glass, and metals (aluminum, copper, iron, stainless steel, etc.) can be used. Preferably, from the viewpoint of heat resistance, polyimide resin, silicone resin, glass, or metal (such as a so-called "metal substrate" with aluminum or copper as the base metal and an insulating layer) can be used. It is also preferable to use commercially available materials under names such as "bonding sheet". The thickness of the insulating substrate 20 is not particularly limited as long as it is within the range that can be used in lighting fixtures. For example, it can be between 50 μm and 1000 μm, specifically between 50 μm and 500 μm.

[0075] The white layer 24 and the white layer 32 can be formed, for example, using 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 phosphor particles in the above-mentioned paint composition can be cited. The application method can be the same as that for the fluorescent coating film 26 described below. Examples of white pigments include well-known pigments such as titanium dioxide. Inorganic pigments are preferred from the viewpoint of stability and other factors. The thickness of the white layer 24 is, for example, between 10 μm and 500 μm, specifically between 20 μm and 400 μm.

[0076] The fluorescent coating 26 can be provided by applying the above-mentioned paint composition. The fluorescent coating 26 converts the light emitted from the light-emitting element into light of a different wavelength / color temperature. The application method is not particularly limited. For example, the paint composition may be applied using various coaters known in the paint industry. Alternatively, the paint composition may be applied by printing methods such as screen printing. It is preferable to perform a drying treatment and a curing treatment after application. The drying treatment conditions are, for example, 60°C to 100°C for 15 minutes to 60 minutes. The curing treatment conditions are, for example, 100°C to 200°C for 30 minutes to 240 minutes.

[0077] The amount of paint composition applied is adjusted so that the thickness of the 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. By ensuring that the phosphor particle content 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 the fluorescent coating film 26 is 150 μm or less, the light emitted from the surface-mount LED element 28 can be sufficiently converted into fluorescence, and the light emitted from the surface-mount LED element 28 does not easily pass through the phosphor layer.

[0078] Furthermore, holes can be created in the cured white layer 24 and / or fluorescent coating 26 by mechanically drilling holes through which the solder 30 can pass. For the subsequent connection of the surface-mount LED element 28 (light-emitting element) and the first copper foil 22 with the solder 30, known methods can be applied as appropriate.

[0079] Examples of surface-mount LED elements 28 (light-emitting elements) include CSPs, SMDs (Surface Mount Devices), and flip-chip elements. In this embodiment, CSPs are preferred as the light-emitting elements. Furthermore, the light-emitting elements typically emit blue light.

[0080] In this embodiment, it is particularly preferable that the light-emitting element does not have a reflector. Specifically, some known surface-mount LED elements (light-emitting elements), as shown in Figure 2A, have a reflector to prevent light from leaking out laterally or downwards from the LED chip. However, in this embodiment, it is preferable that the surface-mount LED element 28 (light-emitting element) does not have a reflector, as shown in Figure 2B. By using a light-emitting element without a reflector, light from the LED chip leaks out laterally and downwards. This leaked light then strikes the area indicated by α in the fluorescent coating 26, causing that area to emit light. This further reduces problems such as glare and multiple shadows.

[0081] In the light-emitting element shown in Figure 2A, a semiconductor light-emitting element 100 is placed 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 be provided with wiring 112. In Figure 2B, the same elements as in Figure 2A are denoted by the same reference numerals. In the light-emitting element of Figure 2B, a housing (reflector) is not used. As shown in the figure, after mounting the semiconductor light-emitting element 100, the sealing member 110 can be formed by molding using a desired mold. Alternatively, a sealing member 110 molded in advance into a desired shape may be prepared and bonded to the substrate 102 so as to cover the semiconductor light-emitting element 100.

[0082] Although embodiments of the present invention have been described above, these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0083] Embodiments of the present invention will be described in detail based on examples and comparative examples. It should be noted that the present invention is not limited to these examples.

[0084] <Materials> I prepared the following: (Phosphor particles) • CASN-1: CASN-type phosphor manufactured by Denka Corporation, product numbers RE-650YMDB, D 50 = 15.7 μm • CASN-2: CASN-type phosphor manufactured by Denka Corporation, product number RE-Sample 650SD4, D 50 = 3.2 μm

[0085] Particle size distribution of phosphor particles (D 50 The following was measured: (1) Dispersion treatment using ultrasound A dispersion of 30 mg of phosphorescent particles was uniformly dispersed in 100 mL of a 0.2% sodium hexametaphosphate aqueous solution. This dispersion was placed in a cylindrical container with a base radius of 2.75 cm. A cylindrical tip with a radius of 10 mm from an ultrasonic homogenizer (US-150E, manufactured by Nippon Seiki Seisakusho Co., Ltd.) was immersed in the dispersion for at least 1.0 cm, 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 described in (1) above was measured using a laser diffraction scattering particle size distribution analyzer (Microtrac Bell, MT3300EXII) to determine the particle size distribution. Furthermore, D was obtained from the particle size distribution data. 50 They sought it.

[0086] (curable resin component) Toray Dow Corning's silicone resin "RSN-0805" (contains silanol groups, silanol content (OH weight) 1%, silicon dioxide content 48% by weight, phenyl:methyl ratio = 1.1:1, weight-average molecular weight 200-300 x 10) 3 xylene-containing, resin solids content 50% by weight

[0087] (Flow modifier) Aerosil 200 Fumed Silica from Nippon Aerosil Co., Ltd.

[0088] (solvent) Butylcarbitol

[0089] <Preparation of paint composition> First, a homogeneous solution was obtained by mixing the curable resin component (silicone resin) and the solvent from the components listed in the table below. Subsequently, phosphor particles and a fluidity modifier (only in Example 3) were added to the solution and uniformly mixed and dispersed to obtain a paint composition. The viscosity of the obtained paint composition was measured using a Type B viscometer with rotor No. 4 at 25°C and a rotation speed of 20 rpm.

[0090] <Formation of coating film (phosphor layer) / Fabrication of lighting device> Using the paint composition prepared above, a lighting device with the structure described in Figure 1 (multiple CSPs arranged at regular intervals on a phosphor layer) was fabricated. The manufacturing procedure is briefly shown below. (1) As the material for the insulating substrate, a bonding sheet CS-3305A manufactured by Rishou Kogyo Co., Ltd., which has copper foil laminated on both sides, was prepared. The copper foil of this sheet 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 a white paint (a mixture of 50 vol% titanium oxide / alumina in a silicone binder). (3) The above-mentioned phosphor coating was printed (film formed) onto the white layer using a screen printing method with a mesh count of 86, pre-cured at 80°C for 30 minutes, and then post-cured (fully cured) at 180°C for 60 minutes. This formed a phosphor layer. The target thickness of the phosphor layer at this time was 50 μm. (4) Holes were drilled in parts of the white layer and phosphor layer to create holes for soldering. Then, a commercially available surface-mount LED element, CSP (WICOP SZ8-Y15-WW-C8, manufactured by Seoul Semiconductor Co., Ltd., without reflector, color temperature 2200~2300K), and the first copper foil (copper circuit) were electrically connected by solder.

[0091] <Evaluation: Printability> In (3) above, if a phosphor layer with a thickness of 45-55 μm was formed, it was evaluated as having good printability (○), and if a phosphor layer of sufficient thickness could not be formed, it was evaluated as having poor printability (×).

[0092] <Evaluation: Appearance of the phosphor layer> The appearance of the phosphor layer formed in (3) above was observed. In Table 2 below, "No abnormalities" is indicated if no abnormalities that could pose practical problems were observed, and the nature of any abnormalities that could pose practical problems is described.

[0093] <Evaluation: Durability of the phosphor layer, etc.> For samples that showed "no abnormalities" in the visual evaluation of the phosphor layer described above, the tests listed in Table 1 below were performed. Samples that met the pass criteria for all items in Table 1 were marked "passed" in Table 2.

[0094] [Table 1]

[0095] <Evaluation: Color temperature conversion> Current was passed through the lighting device prepared as described above, causing it 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. The measured color temperature was 2000-2100K, and if the color temperature was converted by at least 100K from the color temperature of the CSP itself (2200-2300K), it was evaluated as having good color temperature conversion performance ("○"). However, this evaluation was not performed in Comparative Examples 1 and 2, where there were abnormalities in the properties of the phosphor layer.

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

[0097] [Table 2]

[0098] By using a phosphor coating containing phosphor particles and a curable resin component, with a phosphor particle content of 25 vol% to 60 vol% in the total non-volatile components, it was possible to form a phosphor layer at a relatively low temperature of around 180°C without requiring high-temperature sintering like with a glass binder. Furthermore, the appearance and durability of the formed phosphor layer were good. In addition, the color temperature of the light emitted from the CSP was significantly altered by the formed phosphor layer.

[0099] This application claims priority based on Japanese Patent Application No. 2020-134386, filed on 7 August 2020, and incorporates all of its disclosures herein. [Explanation of Symbols]

[0100] 20 Insulating substrate 22 Copper foil 22B Cupric foil 24 White layer 26 Fluorescent coating 28 Surface-mount LED elements 30 solder 32 White layer (white resin layer) 100 Semiconductor light-emitting elements 102 circuit boards 104 Reflector (Housing) 108 Package-like part 110 Sealing member 112 Wiring

Claims

1. A phosphor coating comprising phosphor particles and a curable resin component, The content of the fluorescent particles in the total nonvolatile components is 35 vol% or more and 60 vol% or less. In the particle size distribution curve of the aforementioned phosphor particles, two or more maxima are observed. A phosphor coating in which a maximum is observed in both the region of particle size between 1 μm and 6 μm and the region of particle size between 10 μm and 25 μm in the particle size distribution curve of the phosphor particles.

2. A phosphor coating according to claim 1, The curable resin component is a fluorescent paint containing a thermosetting resin component.

3. A phosphor coating according to claim 1 or 2, The curable resin component is a phosphorescent paint containing a silicone resin.

4. A phosphor coating according to any one of claims 1 to 3, The curable resin component is a phosphorescent coating containing a silicone resin having phenyl and methyl groups.

5. A phosphor coating according to any one of claims 1 to 4, The curable resin component is a phosphorescent coating containing a silicone resin containing a silanol group.

6. A phosphor coating according to any one of claims 1 to 5, Median diameter D of the aforementioned phosphor particles ５０ A phosphor coating having a particle size of 1 μm or more and 20 μm or less.

7. A phosphor coating according to any one of claims 1 to 6, The phosphor particles are one or more selected from the group consisting of CASN-based phosphors, SCASN-based phosphors, La ３ Si ６ N １１ -based phosphors, Sr ２ Si ５ N<s ８ -based phosphors, Ba ２ Si ５ N ８ -based phosphors, α-type sialon-based phosphors, β-type sialon-based phosphors, LuAG-based phosphors, and YAG-based phosphors, and the phosphor paint contains one or more of them. It should be noted that there seems to be an incorrect tag format in your original text, such as ３ which might need to be checked and corrected if it's not a standard format in the context of patent text. I've translated it as it is for now following the rules.

8. A phosphor coating according to any one of claims 1 to 7, A fluorescent paint containing a fluidity modifier.

9. A phosphor coating according to any one of claims 1 to 8, Furthermore, it is a phosphorescent paint containing a solvent.

10. A phosphor coating according to claim 9, The solvent is a phosphorescent paint containing an aromatic hydrocarbon solvent.

11. A phosphor coating according to any one of claims 1 to 10, A phosphorescent paint having a viscosity of 60 dPa·s or more and 500 dPa·s or less, as measured using a B-type viscometer at 25°C and a rotation speed of 20 rpm.

12. A coating film formed by a phosphorescent paint according to any one of claims 1 to 11.

13. The coating film according to claim 12, A coating film with a thickness of 150 μm or less.

14. A phosphor substrate comprising the coating film according to claim 12 or 13.

15. A lighting device comprising: an insulating substrate; a coating film provided on one side of the insulating substrate using a phosphor paint according to any one of claims 1 to 11; and a light-emitting element installed on the side of the coating film opposite to the insulating substrate.

16. A lighting device according to claim 15, A lighting device on which multiple of the aforementioned light-emitting elements are installed.

17. A lighting device according to claim 15 or 16, The aforementioned light-emitting element is a lighting device without a reflector.

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