Fluorescent paint, coating film, phosphor substrate and illumination device

Abstract

To provide a material capable of simply forming a phosphor layer.SOLUTION: A phosphor paint contains phosphor particles, and a curable resin component. Viscosity of the phosphor paint measured at 25°C and rotation frequency of 20 rpm using a B type viscometer is 60 dPa s or more and 450 dPa s or less. A coating film (phosphor layer), a phosphor substrate and an illumination device can be manufactured using the phosphor paint.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Various developments are underway for lighting devices that use LEDs (Light Emitting Devices). Not only the development of LEDs themselves, but also the development of mounting boards that have LEDs is also known.

[0003] For example, Example 2 of Patent Document 1 describes the following: (i) a glass binder paint containing 30 vol% phosphor was applied to the surface of a glass substrate to form a phosphor layer having a thickness of 200 μm; (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 design in which the LED chip is wrapped in phosphor resin and consists of only the LED chip and phosphor resin.) [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 093339 Summary of the Invention [Problem to be solved by the invention]

[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 sufficiently harden the glass binder paint, there is room for improvement in terms of the ease of providing the phosphor layer. In addition, the housing / substrate to which the glass binder paint is applied 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 the above circumstances, and an object of the present invention is to provide a material from which a phosphor layer can be easily formed. [Means for solving the problem]

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

[0008] According to the present invention, [1] A phosphor coating material comprising phosphor particles and a curable resin component, A phosphor paint with a viscosity of 60 dPa·s or more and 450 dPa·s or less, measured at 25°C and 20 rpm using a B-type viscometer. [2] The phosphor coating material according to [1], The curable resin component is a phosphor paint containing a thermosetting resin component. [3] The phosphor coating material according to [1] or [2], The curable resin component is a phosphor paint containing a silicone resin. [4] The phosphor coating material according to any one of [1] to [3], The curable resin component is a phosphor paint containing a silicone resin having a phenyl group and a methyl group. [5] The phosphor coating material according to any one of [1] to [4], The curable resin component is a phosphor paint containing a silicone resin containing a silanol group. [6] [1] to [5], The median diameter D of the phosphor particles 50 is a phosphor paint with a thickness of 1 μm or more and 20 μm or less [7] [1] to [6], wherein the phosphor coating material is A phosphor coating material in which two or more maxima are observed in the particle size distribution curve of the phosphor particles. [8] [7] The phosphor coating material according to the present invention, A phosphor coating material in which a particle size distribution curve of the phosphor particles shows a maximum in both a particle size region of 1 μm to 6 μm and a particle size region of 10 μm to 25 μm. [9] [1] to [8], wherein the phosphor coating material is The phosphor particles are CASN-based phosphors, SCASN-based phosphors, La3Si6N 11 a phosphor coating material containing one or more selected from the group consisting of a ZnO-based phosphor, a Sr2Si5N8-based phosphor, a Ba2Si5N8-based phosphor, an α-type sialon-based phosphor, a β-type sialon-based phosphor, a LuAG-based phosphor, and a YAG-based phosphor.

[10] [1] to [9], Phosphor paint containing flow control agent

[11] [1] Any one of the phosphor coating materials according to [1] to

[10] , Further, phosphor paint containing solvent

[12]

[11] The phosphor coating material according to the present invention, The solvent is a phosphor paint containing an aromatic hydrocarbon solvent. is provided.

[0009] Further, according to the present invention,

[13] A coating film formed from the phosphor coating material according to any one of [1] to

[12] .

[14]

[13] The coating film according to the present invention, Coating film with a thickness of 150 μm or less is provided.

[0010] Further, according to the present invention,

[15] A phosphor substrate having the coating film according to

[13] or

[14] . is provided.

[0011] Further, according to the present invention,

[16] A lighting device comprising: an insulating substrate; a coating film formed on one side of the insulating substrate using the phosphor coating material according to any one of [1] to

[12] ; and a light-emitting element disposed on a surface of the coating film opposite the insulating substrate.

[17]

[16] The lighting device according to

[16] , A lighting device having a plurality of the light emitting elements

[18]

[16] or

[17] , wherein the lighting device comprises: The light emitting element is a lighting device without a reflector. is provided. Effect of the Invention

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

[0013] [Figure 1] FIG. 2 is a schematic cross-sectional view of a lighting device. [Diagram 2] 1A and 1B are diagrams for explaining an LED chip without a reflector and an LED chip with a reflector. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all drawings, similar components are given similar symbols and descriptions thereof are 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 the actual objects.

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

[0016] <Phosphor paint> The phosphor coating material of the present embodiment contains phosphor particles and a curable resin component. The phosphor coating material of this embodiment has a viscosity of 60 dPa·s or more and 450 dPa·s or less when measured using a Brookfield viscometer at 25° C. and a rotation speed of 20 rpm. 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 the present 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] Not needing sintering at high temperatures means that usable phosphors are not limited. Specifically, when trying to obtain a cured film with a glass binder, firing at a high temperature of about 600°C is required. When such a high temperature is required, it is necessary to select a phosphor that can withstand high temperatures, which may limit the usable phosphors. Also, peeling is likely to occur when cooling from a high temperature. However, by preparing a phosphor coating using a curable resin component, it is possible to form a phosphor layer that is less likely to peel off without requiring a high temperature of about 600°C. The fact that high-temperature sintering is not required also has the advantage that there are fewer restrictions on the heat resistance and optimization of the expansion coefficient of the housing / substrate to which the paint is applied or printed.

[0019] In addition, by using a curable resin component, it is easy to form a suitably thin phosphor layer by coating or printing, which is particularly effective when the phosphor coating contains a large amount 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 appropriate thickness and with little unevenness can be formed on a substrate by, for example, a screen printing method suitable for mass production.

[0020] In this embodiment, a phosphor coating having a viscosity of 60 dPa·s or more and 450 dPa·s or less can be obtained by using an appropriate amount of an appropriate material, etc. Specifically, the phosphor coating of this embodiment can be manufactured by using an appropriate amount of phosphor particles having an appropriate particle size distribution, an appropriate amount of an appropriate flowability modifier, an appropriate amount of an appropriate 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 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 and color temperature, only one type of specific phosphor particles may be used, or two or more types of phosphor particles may be used in combination.

[0023] The phosphor particles are CASN phosphor, SCASN phosphor, La3Si6N 11 The phosphor may be one or more selected from the group consisting of α-type SiAlON phosphors, Sr2Si5N8-type phosphors, Ba2Si5N8-type phosphors, α-type SiAlON phosphors, β-type SiAlON phosphors, LuAG-type phosphors, and YAG-type phosphors. These phosphors usually contain activating elements such as Eu and Ce.

[0024] The CASN phosphor (a type of nitride phosphor) preferably contains Eu. The CASN phosphor is, for example, represented by the formula CaAlSiN3:Eu 2+ It is represented by Eu 2+ This refers to a red phosphor that uses as an activator and has a crystal matrix made of alkaline earth silicon nitride. In the definition of Eu-containing CASN-based phosphors in this specification, Eu-containing SCASN-based phosphors are excluded.

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

[0026] La3Si6N 11 Specifically, the phosphor is La3Si6N 11 :Ce phosphors, etc. This usually converts the blue light from a blue LED into yellow light.

[0027] Specifically, the Sr2Si5N8 phosphor is Sr2Si5N8:Eu 2+ Phosphors and Sr2Si5N8:Ce 3+ These usually convert the blue light from a blue LED into yellow to red light.

[0028] A Ba2Si5N8 phosphor is specifically Ba2Si5N8:Eu, which usually 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, represented by the general formula: x EU y S 12-(m+n) Al (m+n) O n N 16-nIt is represented by. 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 + 2y = m, where 0 < x ≦ 1.5, 0.3 ≦ m < 4.5, and 0 < n < 2.25.

[0030] The β - type sialon - based phosphor preferably contains Eu. The β - type 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 - type sialon in which Eu 2+ is solid - dissolved. 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 - type sialon, it is preferably 0.005 or more and 1.0 or less. Also, the europium content is preferably 0.1 mass% or more and 2.0 mass% or less.

[0031] The LuAG - based phosphor usually means a lutetium aluminum garnet crystal. Considering its application to lighting devices, 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.

[0032] The YAG - based phosphor usually means a yttrium aluminum garnet crystal. Considering its application to lighting devices, the YAG - based phosphor is preferably activated with Ce. More specifically, the YAG - based phosphor can be represented by the composition formula of Y3Al5O 12 :Ce, but the composition of the YAG - based phosphor does not necessarily have to follow stoichiometry.

[0033] Commercially available phosphor particles may be used. Examples of commercially available phosphor particles include Alonbright (registered trademark) from Denka Co., Ltd. In addition, they are also commercially available from Mitsubishi Chemical Corporation.

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

[0035] It is preferable that the particle size distribution curve of the phosphor particles has two or more maxima. Specifically, it is preferable that the maxima are found in both the region of particle size 1 μm to 6 μm and the region of particle size 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 using only large particles. In addition, even if the phosphor particle content is increased, the various physical properties of the paint are easily maintained. Furthermore, when the paint is made into a coating film, the light emitted from the light emitting element is less likely to transmit.

[0036] Median diameter of phosphor particles D 50 The particle size distribution curve can be adjusted by devising a method for preparing phosphor particles, by appropriately crushing 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 phosphor particles in a dispersion medium using an ultrasonic homogenizer and then using a laser diffraction scattering type particle size distribution measuring device. From the particle size distribution curve obtained, the median diameter D 50 For details of the dispersion treatment and the measurement device, see the Examples described later. Just to be clear, in this specification, the median diameter D 50 and particle size distribution curves are measured on a volume basis.

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

[0039] By setting the content of phosphor particles in the total non-volatile components of the phosphor coating material to 25 vol % or more, for example, light emitted from a light emitting element can be sufficiently converted into fluorescence. Another advantage is that the coating or printing suitability is further improved. Since the content of phosphor particles in the phosphor coating material is appropriately high, the phosphor coating material becomes appropriately less prone to flow, and as a result, it becomes easier to form a phosphor layer with an appropriate thickness. By making the phosphor particle content in the total non-volatile components of the phosphor paint 25 vol% or more, there is also the advantage that cracks are less likely to occur in the phosphor layer. Based on general knowledge, one of the causes 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 provided. By making the phosphor particle content in the total non-volatile components of the phosphor paint 25 vol% or more, the curable resin component is relatively reduced. This reduces the difference in thermal expansion coefficient between the phosphor layer and the substrate on which the phosphor layer is provided. As a result, it is thought that cracks are 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, for example, even if the phosphor layer is thin, the light emitted from the light-emitting element can be sufficiently converted into fluorescence, and the color temperature of the light emitted from the light-emitting element can be significantly changed.

[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 the present 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 the formation of a coating film, but that can be polymerized to form a resin (polymer) by the action of heat, light, etc. after the formation of a coating film. In relation to the above, in this specification, in addition to polymers, monomers, or oligomers, polymerization initiators, curing agents, and the like are also included in the "curable resin component".

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

[0044] The curable resin component preferably contains a thermosetting resin component. This allows a lighting device with high durability to be manufactured. Of course, depending on the purpose or use, the curable resin component may 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, and the like.

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

[0047] The hardenable resin component may contain reactive groups, which allows the hardenable resin component to cure by itself. As an example, the curable resin component preferably contains a silicone resin containing a silanol group (-Si-OH). This causes a condensation reaction of the silanol group during coating film formation, resulting in a cured coating film. The silanol content (OH weight %) of the silicone resin containing a silanol group (-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 by 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, and as long as it can form a coating film as a coating material, a resin of any weight average molecular weight can be contained. 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, and 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] The resin contained in the curable resin component may be a commercially available product. Commercially available silicone resins are available from, for example, Dow Corning Toray Co., Ltd. and Shin-Etsu Chemical Co., Ltd. Examples of such products include RSN-0409, RSN-0431, RSN-0804, RSN-0805, RSN-0806, RSN-0808, RSN-0840, etc. (manufactured by Dow Corning Toray Co., Ltd.), 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, etc. (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0050] As mentioned above, the curable resin component may include monomers or oligomers rather than 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 in addition to a monomer or oligomer. For example, when the curable resin component contains a (meth)acrylate monomer, it is preferable to use it in combination with a radical polymerization initiator. The radical polymerization initiator generates radicals by heat or active light.

[0052] The curable resin component may be any component known in the coating field, such as the silicone resin 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 bifunctional to hexafunctional, more preferably bifunctional to tetrafunctional. Specific examples include aliphatic diisocyanates, cyclic aliphatic diisocyanates, isocyanurate and biuret adducts which are polymers of isocyanate compounds, and isocyanate compounds added to polyhydric alcohols or low molecular weight polyester resins. Biuret, isocyanurate, adduct, and allophanate types of polyisocyanates are also known. Any of these can be used.

[0055] The polyisocyanate (i) may be a so-called blocked isocyanate. In other words, a part or all of the isocyanate groups of the polyisocyanate may be in the form of blocked isocyanate groups blocked by protective 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 methylenes.

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

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

[0058] The phosphor coating material of the present 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 % or more and 65 vol % or less, more preferably 45 vol % or more and 60 vol % or less, based on the total non-volatile components.

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

[0060] As the flowability adjusting agent, silica particles such as hydrophobic silica and hydrophilic silica, aluminum oxide, etc. can be used. In particular, fumed silica is preferably used. Examples of commercially available flow adjusters 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, product name).

[0061] When the phosphor coating material of the present embodiment contains a flowability modifier, it may contain only one type of flowability modifier, or may contain two or more types of flowability modifiers. When the phosphor coating material of the present embodiment contains a flowability modifier, the amount of the flowability modifier is, for example, 10 vol% or less, preferably 1 vol% to 5 vol% of 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% to 5 mass% of the total non-volatile components.

[0062] (solvent) The phosphor coating material of the present embodiment preferably contains a solvent. This makes it possible to obtain a phosphor coating material with good coatability. The solvent contains water and / or an organic solvent. Examples of the organic solvent 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. In addition, ether bond-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 silicone resin is used as the resin, because they can dissolve / disperse the silicone resin well and prepare a phosphor coating material with good coatability.

[0064] In addition, the solvent preferably contains an aromatic hydrocarbon solvent. In particular, when a silicone resin is used, it is easy to prepare a phosphor coating material with a good balance of various performances by using the silicone resin in combination with an aromatic hydrocarbon solvent. Examples of the aromatic hydrocarbon solvent include toluene and xylene.

[0065] When using a solvent, 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 using solvents in combination, it is preferable that each solvent is 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 the present embodiment contains a solvent, it is preferable that the solvent is contained in an amount such that the concentration of non-volatile components is 90 mass % or less. However, the concentration of non-volatile components is not limited to this, and the amount may be appropriately adjusted as long as a coating film can be formed.

[0066] (Other ingredients) The phosphor coating material of the present 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 using a Brookfield viscometer at 25°C and 20 rpm, is 60 dPa·s or more and 450 dPa·s or less. The viscosity is preferably 80 dPs·s or more and 350 dPa·s or less, and more preferably 90 dPs·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 a screen printing method.

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

[0069] <Coating film, phosphor substrate, lighting device> The above phosphor coating material can be used to form a coating film containing phosphor particles. Moreover, by using the above phosphor coating material, a phosphor substrate having a coating film containing phosphor particles can be manufactured. Furthermore, using the above-mentioned phosphor paint, a lighting device can be manufactured that includes an insulating substrate, a coating film made of the above-mentioned phosphor paint provided on one side of the insulating substrate, and a light-emitting element (such as an LED element) installed on the surface of the coating film opposite the insulating substrate.

[0070] Hereinafter, the coating film, the phosphor substrate, and the lighting device will be described with reference to examples of the configuration of the lighting device.

[0071] FIG. 1 is a schematic cross-sectional view of a lighting device. 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 part 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 provided 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 so as to penetrate the white layer 24 and the fluorescent coating 26. Electricity is supplied to the surface-mounted LED element 28 by the first copper foil 22 and the solder 30, causing the surface-mounted LED element 28 to emit light. From the viewpoint of increasing the luminous efficiency of the phosphor coating, it is preferable to provide a white layer 32 (more specifically, a white resin layer 32) under the surface-mounted LED element 28. This prevents light from escaping (transmitting). In addition, at least a part of the light incident from the phosphor coating 26 is reflected at the interface between the white layer 32 and the phosphor coating 26. The lighting device of FIG. 1 may include a number of 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 PWB (printed wiring board). For example, polyimide resin, silicone resin, (meth)acrylic resin, urea resin, epoxy resin, fluororesin, glass, metal (aluminum, copper, iron, stainless steel, etc.) can be used. From the viewpoint of heat resistance, it is preferable to use polyimide resin, silicone resin, glass, or metal (such as a so-called "metal substrate" using aluminum or copper as a base metal and provided with an insulating layer). It is also preferable to use a material that is commercially available under the name of "bonding sheet" or the like. The thickness of the insulating substrate 20 is not particularly limited as long as it is within a range that allows use in a lighting fixture, and is, for example, 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 provided by 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 mentioned. The coating method can be the same as that of the fluorescent coating film 26 described below. Examples of the white pigment include known pigments such as titanium oxide, etc. From the viewpoint of stability, inorganic pigments are preferred. 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 provided by applying the above-mentioned coating 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. A preferred method is a printing method such as a screen printing method. In this embodiment, the viscosity of the coating composition is 60 dPa·s or more and 450 dPa·s or less, so that a uniform fluorescent coating film 26 with an appropriate thickness can be provided by applying a screen printing method. Of course, the application method may be other methods, and for example, the coating composition may be applied using various coaters known in the coating field. After application, it is preferable to carry out a drying treatment and a hardening treatment. The drying treatment conditions are, for example, 60° C. to 100° C. and 15 minutes to 60 minutes. The hardening treatment conditions are, for example, 100° C. to 200° C. and 30 minutes to 240 minutes.

[0077] The amount of the coating 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 or more and 100 μm or less, and even more preferably 30 μm or more and 80 μm or less. By ensuring that 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 the fluorescent coating film 26 is 150 μm or less, the light emitted from the surface-mounted LED element 28 can be sufficiently converted into fluorescence, and the light emitted from the surface-mounted LED element 28 is less likely to pass through the phosphor layer.

[0078] Incidentally, holes through which the solder 30 penetrates can be provided by mechanically drilling the cured white layer 24 and / or the fluorescent coating film 26. The subsequent connection between the surface mount type LED element 28 (light emitting element) and the first copper foil 22 by the solder 30 can be appropriately performed using a known method.

[0079] Examples of the surface mount type 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 usually emits blue light.

[0080] In this embodiment, it is particularly preferable that the light-emitting element does not include a reflector. To be more specific, some known surface-mounted LED elements (light-emitting elements) are provided with a reflector as shown in Fig. 2A, so that light from the LED chip does not leak out in the lateral or downward directions. 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, the light from the LED chip leaks out sideways and downwards. The leaked light hits the part of the fluorescent coating 26 indicated by α, causing the part to emit light. This further reduces the problems of glare and multiple shadows.

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

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

[0083] The 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 the Examples.

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

[0085] Size distribution of phosphor particles (D 50 ) was measured as follows. (1) Dispersion treatment using ultrasonic waves A dispersion liquid in which 30 mg of phosphor particles were uniformly dispersed in 100 mL of a 0.2% aqueous solution of sodium hexametaphosphate was placed in a cylindrical container with a bottom radius of 2.75 cm. The cylindrical tip of an ultrasonic homogenizer (Nippon Seiki Seisakusho, US-150E) with a radius of 10 mm was immersed in the dispersion liquid to a depth of 1.0 cm or more, and ultrasonic waves were irradiated at a frequency of 19.5 kHz and an output of 150 W for 3 minutes. (2) Measurement of particle size distribution The dispersion liquid prepared as described above in (1) was measured using a laser diffraction scattering type particle size distribution measuring device (Microtrackbell, MT3300EXII) to obtain the particle size distribution. 50 asked for.

[0086] (curable resin component) Toray Dow Corning silicone resin "RSN-0805" (containing 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 × 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> Among the components shown in the table below, first, the curable resin component (silicone resin) and a solvent were mixed to obtain a homogeneous solution. Thereafter, phosphor particles and a flowability modifier (only in Example 3) were added to the solution, and mixed and dispersed uniformly to obtain a coating composition. The viscosity of the resulting coating composition was measured using a No. 4 rotor of a Brookfield type viscometer at 25° C. and a rotation speed of 20 rpm.

[0090] <Formation of coating film (phosphor layer) / production of lighting device> Using the coating composition prepared above, a lighting device with the structure described in Figure 1 (multiple CSPs aligned on a phosphor layer at regular intervals) was fabricated. The manufacturing procedure is briefly described below. (1) As the material for the insulating substrate, we prepared a bonding sheet CS-3305A manufactured by Risho Kogyo Co., Ltd., with copper foil on both sides. We etched the copper foil 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 mixture of titanium oxide / alumina at 50 vol% with a silicone binder). (3) On the white layer, the above phosphor paint was printed (film formation) by screen printing using a screen with a mesh number of 86, pre-cured at 80°C for 30 minutes, and then post-cured (main curing) at 180°C for 60 minutes. This formed the phosphor layer. The thickness of the phosphor layer was targeted to be 50 μm. (4) Part of the white layer and phosphor layer were drilled to provide holes for soldering. A commercially available CSP (WICOP SZ8-Y15-WW-C8, Seoul Semiconductor, reflector-less, color temperature 2200-2300K), which is a surface-mount type LED element, was electrically connected to the first copper foil (copper circuit) by soldering.

[0091] <Evaluation: Printability> In the above (3), If the printed phosphor coating does not flow before pre-curing and a uniform phosphor layer with a thickness of 45 to 55 μm is formed, the printability is considered to be good (○). Although the printed phosphor coating flows slightly before pre-curing, if a uniform phosphor layer with a thickness of 45 to 55 μm is formed, the printability is considered to be fair (△). If the phosphor layer is not thick enough or if there are uneven spots on the film, it is considered poor printability (×). It was rated as follows:

[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 problem in practical use was found are recorded as "no abnormality", and cases where an abnormality that could be a problem in practical use was found are recorded as the details of the abnormality.

[0093] <Evaluation: Durability of phosphor layer, etc.> Products that were found to be "normal" in the above appearance evaluation of the phosphor layer were subjected to the tests listed in Table 1. Products that met the pass criteria for all items in Table 1 are listed as "passed" in Table 2.

[0094] [Table 1]

[0095] <Evaluation: Color temperature conversion> A current was passed through the lighting device prepared above to cause the lighting device to emit light. The color temperature of the light emitted from the lighting device was measured using a total luminous flux measuring system (equipment equipped with an integrating sphere) manufactured by Otsuka Electronics Co., Ltd. When the measured color temperature was 2000-2100K and the color temperature was converted by at least 100K from the color temperature of the CSP itself (2200-2300K), the color temperature conversion property was evaluated as good (○). On the other hand, when the measured color temperature was 2100-2200K and the color temperature conversion was limited to within 100K, the color temperature conversion property was evaluated as insufficient (×). In addition, in Comparative Example 2 in which the phosphor layer had abnormal properties, this evaluation was not performed.

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

[0097] [Table 2]

[0098] By using a phosphor paint containing phosphor particles and a curable resin component, with a viscosity of 60 dPa·s to 450 dPa·s measured at 25°C and 20 rpm using a B-type viscometer, it was possible to form a phosphor layer at a relatively low temperature of around 180°C, without the need for high-temperature sintering as with glass binders. Furthermore, the appearance and durability of the formed phosphor layer were good. 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. [Explanation of symbols]

[0100] 20 Insulating substrate 22 Copper foil 22B Cupric foil 24 White layer 26 Fluorescent Coating 28 Surface-mounted LED elements 30 Solder 32 White layer (white resin layer) 100 Semiconductor light emitting element 102 Substrate 104 Reflector (Housing) 108 Package shape 110 Sealing member 112 Wiring

Claims

[Claim 1] A phosphor coating material comprising phosphor particles and a curable resin component, A phosphor coating material having a viscosity of 60 dPa·s or more and 450 dPa·s or less, measured at 25° C. and a rotation speed of 20 rpm using a Brookfield viscometer.

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