阅读说明：本技术 包覆荧光体、其制造方法、以及荧光体片和发光装置 (Coated phosphor, method for producing same, phosphor sheet, and light-emitting device ) 是由 山菅雄大 阿部守晃 八木桥和弘 楠木常夫 于 2018-11-05 设计创作，主要内容包括：本发明涉及一种包覆荧光体,该包覆荧光体具有无机荧光体颗粒和包覆上述无机荧光体颗粒的氧化硅覆膜,关于上述包覆荧光体的在ICP发光分光分析中的上述氧化硅覆膜的氧原子与硅原子的摩尔比(O/Si)为2.60以下。(The present invention relates to a coated phosphor having inorganic phosphor particles and a silicon oxide film coating the inorganic phosphor particles, wherein a molar ratio (O/Si) of oxygen atoms to silicon atoms of the silicon oxide film in ICP emission spectroscopy of the coated phosphor is 2.60 or less.)

1. A coated phosphor is characterized by comprising:

inorganic phosphor particles; and

a silicon oxide coating film covering the inorganic phosphor particles,

the silicon oxide film has an O/Si ratio of 2.60 or less, which is a molar ratio of oxygen atoms to silicon atoms in ICP emission spectroscopy of the coated phosphor.

2. The coated phosphor of claim 1,

the average thickness of the silicon oxide coating is 3nm to 200 nm.

3. The coated phosphor of claim 1 or 2,

the inorganic phosphor particles are represented by any one of the following general formulae (1) to (3):

Sr_1－xGa₂S₄：Eu_xgeneral formula (1);

(Sr_1－yCa_y)_1－xGa₂S₄：Eu_xgeneral formula (2);

(Ba_zSr_1－z)_1－xGa₂S₄：Eu_xgeneral formula (3);

in the general formulas (1) to (3), x is 0 < x < 1, y is 0 < y < 1, and z is 0 < z < 1.

4. A method for producing a coated phosphor, comprising the steps of:

a coating step of forming a silicon oxide coating on the surface of the inorganic phosphor particles to obtain a coated phosphor; and

and a heating step of heating the coated phosphor at a temperature exceeding the temperature at which the silicon oxide coating film is formed and in an inert atmosphere.

5. The method for producing a coated phosphor according to claim 4,

the temperature of the heating is less than 1000 ℃.

6. The method for producing a coated phosphor according to claim 4 or 5, wherein,

the method for producing a coated phosphor according to any one of claims 1 to 3.

7. A phosphor sheet, characterized in that,

the coated phosphor according to any one of claims 1 to 3.

8. A light-emitting device is characterized in that,

having the phosphor plate of claim 7.

Technical Field

The present invention relates to a coated phosphor, a method for producing the same, a phosphor sheet, and a light-emitting device.

Background

Pseudo-white L ED using yellow phosphors YAG: Ce has been used for low-cost TVs and displays.

In order to expand the color gamut (to realize a wide color gamut), it is advantageous to use a three-wavelength white L ED in which a green-emitting phosphor and a red-emitting phosphor having transmission characteristics of a color filter are used instead of a yellow phosphor.

In this way, inorganic phosphors of respective colors are used in the light emitting device.

Inorganic phosphors are more stable to the external environment than organic phosphors. However, the inorganic phosphor is deteriorated with time, and the light emission characteristics of the inorganic phosphor are sometimes degraded.

Thus, it has been proposed to coat the surface of an inorganic phosphor with another inorganic substance (see, for example, patent documents 1 to 3). Examples of the inorganic coating include a silica coating (see, for example, patent document 1). The silica coating film is generally formed by a sol-gel method using a silicon compound represented by a silane coupling agent.

However, particularly under high temperature and high humidity conditions in a state where L ED (light emitting diode) is lit, further improvement in stability is required.

Disclosure of Invention

Technical problem

The present invention has been made in view of the above circumstances, and an object thereof is to provide a coated phosphor in which an inorganic phosphor is coated with a silicon oxide coating, which is excellent in stability under high temperature and high humidity in an L ED lit state, a method for producing the same, and a phosphor sheet and a light-emitting device using the same.

Means for solving the problems

Means for solving the above problems are as follows. That is to say that the first and second electrodes,

< 1 > a coated phosphor, characterized by having:

inorganic phosphor particles; and

a silica coating film covering the inorganic phosphor particles,

the silicon oxide film has a molar ratio of oxygen atoms to silicon atoms (O/Si) of 2.60 or less in ICP emission spectroscopy of the coated phosphor.

< 2 > the coated phosphor of < 1 > wherein the average thickness of the silicon oxide coating is 3nm to 200 nm.

The coated phosphor of any one of < 3 > the above < 1 > - < 2 >, wherein the inorganic phosphor particles are represented by any one of the following general formulae (1) to (3).

Sr_1－xGa₂S₄：Eu_xGeneral formula (1)

(Sr_1－yCa_y)_1－xGa₂S₄：Eu_xGeneral formula (2)

(Ba_zSr_1－z)_1－xGa₂S₄：Eu_xGeneral formula (3)

In the general formulae (1) to (3), x satisfies 0 < x < 1. y is 0 < y < 1. z satisfies 0 < z < 1.

< 4 > a method for producing a coated phosphor, comprising the steps of:

a coating step of forming a silicon oxide coating on the surface of the inorganic phosphor particles to obtain a coated phosphor; and

and a heating step of heating the coated phosphor at a temperature exceeding the temperature at which the silicon oxide film is formed and in an inert atmosphere.

< 5 > and < 4 > wherein the heating temperature is less than 1000 ℃.

The method for producing a coated phosphor according to any one of < 6 > to < 4 > to < 5 >, wherein the method for producing a coated phosphor according to any one of < 1 > to < 3 > is provided.

< 7 > a phosphor sheet, characterized by containing the coated phosphor described in any one of the above < 1 > to < 3 >.

< 8 > a light-emitting device, characterized in that: the phosphor sheet having the above-mentioned < 7 >.

Effects of the invention

The present invention provides a coated phosphor which is excellent in stability under high temperature and high humidity in an L ED lit state among coated phosphors in which an inorganic phosphor is coated with a silicon oxide coating, a method for producing the same, and a phosphor sheet and a light-emitting device using the same.

Drawings

FIG. 1 is a schematic sectional view showing an example of the structure of an end portion of a phosphor sheet.

Fig. 2 is a schematic cross-sectional view showing an edge-light type light emitting device.

FIG. 3 is a schematic sectional view showing a direct type light-emitting device.

FIG. 4 is a graph showing the molar ratio (O/Si) of the coated phosphors of examples 1 to 5 and comparative example 1 by ICP-AES analysis.

Fig. 5A is an SEM photograph of the coated phosphor not subjected to the annealing treatment.

FIG. 5B is an SEM photograph of the coated phosphor annealed at 600 ℃.

FIG. 5C is an SEM photograph of a coated phosphor annealed at 700 ℃.

FIG. 5D is an SEM photograph of a coated phosphor annealed at 800 ℃.

FIG. 5E is an SEM photograph of a coated phosphor annealed at 900 ℃.

Fig. 6A is a graph showing the result of the beam maintenance ratio at 140mA energization in the reliability test.

Fig. 6B is a graph showing the result of the beam maintenance ratio in the storage (unlit) in the reliability test.

Fig. 7A is a graph showing the result of the index of change in chromaticity when 140mA was energized in the reliability test.

Fig. 7B is a diagram showing the result of the chromaticity change index in the storage (unlit) in the reliability test.

Detailed Description

(coated phosphor)

The coated phosphor of the present invention has inorganic phosphor particles and a silica coating, and further has other components as necessary.

The present inventors have conducted intensive studies to provide a coated phosphor which is coated with an inorganic phosphor by a silicon oxide coating and has excellent stability under high temperature and high humidity in an L ED lit state.

As a result, they have found that a coated phosphor obtained by coating an inorganic phosphor with a silicon oxide film and then heating the silicon oxide film is excellent in stability under high temperature and high humidity in an L ED lit state.

When the change of the silicon oxide film before and after the application of heat was observed, it was found that the molar ratio of oxygen atoms to silicon atoms (O/Si) was changed. This is considered to be influenced by the densification of the silicon oxide coating.

From the above findings, the present inventors have found that a coated phosphor in which an inorganic phosphor is coated with a silicon oxide film has an excellent stability under high temperature and high humidity in an L ED lit state can be obtained by setting the molar ratio (O/Si) of oxygen atoms to silicon atoms in the silicon oxide film to 2.60 or less in ICP emission spectroscopy, and have completed the present invention.

The molar ratio (O/Si) of the oxygen atoms to the silicon atoms of the silicon oxide film in ICP emission spectroscopy of the coated phosphor is 2.60 or less, and when the molar ratio (O/Si) exceeds 2.60, the stability under high temperature and high humidity in the L ED lit state is lowered.

The molar ratio (O/Si) is preferably 2.00 or more and 2.60 or less, more preferably 2.30 or more and 2.55 or less, and particularly preferably 2.30 or more and 2.45 or less.

The molar ratio (O/Si) can be determined by ICP emission spectroscopy.

In the ICP emission spectroscopic analysis, a solution obtained by dissolving the entire coated phosphor may be used as a measurement sample, or a solution obtained by separating the silica coating from the coated phosphor and dissolving the separated silica coating may be used as a measurement sample.

For example, a solution obtained by dissolving the whole of the coated phosphor by an alkali dissolution method using sodium carbonate (JIS R9301-3-3) can be used as a measurement sample.

< inorganic phosphor particle >

The inorganic phosphor particles are not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: green phosphor, red phosphor, yellow phosphor, and the like. Among them, a green phosphor is preferable.

The emission peak wavelength of the green phosphor is, for example, 530nm to 550 nm.

The emission peak wavelength of the red phosphor is, for example, 620nm to 670 nm.

Examples of the inorganic phosphor particles include: sulfide-based phosphors, oxide-based phosphors, nitride-based phosphors, fluoride-based phosphors, and the like. These phosphors may be used alone or in combination of two or more.

The inorganic phosphor particles preferably contain sulfur as a constituent.

Sulfide phosphor

Examples of the sulfide-based phosphor include the following phosphors.

(i) A red sulfide phosphor (CaS: Eu (calcium sulfide (CS) phosphor), SrS: Eu) having a red fluorescence peak with a wavelength of 620nm to 670nm upon irradiation with blue excitation light;

(ii) a green sulfide phosphor (thiogallate (SGS) phosphor (Sr) having a green fluorescence peak with a wavelength of 530nm to 550nm upon irradiation with blue excitation light_xM_1－x－y)Ga₂S₄：Eu_y(M is any one of Ca, Mg and Ba, x is more than or equal to 0 and less than 1, and y is more than 0 and less than 0.2);

(iii) the green sulfide phosphor and the red sulfide phosphor (Ca)_1－x)S：Eu_x(satisfying 0 < x < 0.05).

Specific examples of the sulfide-based phosphor are not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: and (2) CaS: eu (calcium sulfide (CS) phosphor), SrS: eu, SrGa₂S₄：Eu、CaGa₂S₄：Eu、(Sr、Ca、Ba、Mg)Ga₂S₄: eu (thiogallate (SGS) phosphor), (Sr, Ca, Ba) S: eu, Y₂O₂S：Eu、La₂O₂S：Eu、Gd₂O₂S: eu, and the like. These phosphors may be used alone or in combination of two or more.

Oxide phosphor

Specific examples of the oxide phosphor are not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: (Ba, Sr)₃SiO₅：Eu、(Ba、Sr)₂SiO₄：Eu、Tb₃Al₅O₁₂：Ce、Ca₃Sc₂Si₃O₁₂: ce, and the like. These phosphors may be used alone or in combination of two or more.

The oxide phosphor includes an oxide phosphor that emits red fluorescence having a wavelength of 590nm to 620nm upon irradiation with blue excitation light, and is preferably (Ba, Sr)₃SiO₅：Eu、(Ba、Sr)₂SiO₄: eu, and the like.

Nitride phosphor

Specific examples of the nitride-based phosphor are not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include Ca₂Si₅N₈：Eu、Sr₂Si₅N₈：Eu、Ba₂Si₅N₈：Eu、(Ca、Sr、Ba)₂Si₅N₈：Eu、Ca_x(Al、Si)₁₂(O、N)₁₆：Eu(0＜x≦1.5)、CaSi₂O₂N₂：Eu、SrSi₂O₂N₂：Eu、BaSi₂O₂N₂：Eu、(Ca、Sr、Ba)Si₂O₂N₂：Eu、CaAl₂Si₄N₈：Eu、CaSiN₂：Eu、CaAlSiN₃：Eu、(Sr、Ca)AlSiN₃: eu, and the like. These phosphors may be used alone or in combination of two or more.

Fluoride phosphor

Specific examples of the fluoride-based phosphor are not particularly limited, and may be appropriately selected depending on the purpose, and examples thereof include K₂TiF₆：Mn⁴⁺、Ba₂TiF₆：Mn⁴⁺、Na₂TiF₆：Mn⁴⁺、K₃ZrF₇：Mn⁴⁺、K₂SiF₆：Mn⁴⁺And the like. These phosphors may be used alone or in combination of two or more.

Among these inorganic phosphor particles, inorganic phosphor particles represented by any one of the following general formulae (1) to (3) are preferably used in the coated phosphor of the present invention.

Sr_1－xGa₂S₄：Eu_xGeneral formula (1);

(Sr_1－yCa_y)_1－xGa₂S₄：Eu_xgeneral formula (2);

(Ba_zSr_1－z)_1－xGa₂S₄：Eu_xgeneral formula (3).

In the general formulae (1) to (3), x satisfies 0 < x < 1. y is 0 < y < 1. z satisfies 0 < z < 1.

As x, it is preferably 0.03. ltoreq. x.ltoreq.0.20, more preferably 0.05. ltoreq. x.ltoreq.0.18.

As y, it preferably satisfies 0.005. ltoreq. y.ltoreq.0.45, more preferably satisfies 0.05. ltoreq. y.ltoreq.0.20.

As z, it preferably satisfies 0.005. ltoreq. z.ltoreq.0.45, more preferably satisfies 0.20. ltoreq. z.ltoreq.0.40.

< silicon oxide coating film >

In the coated phosphor, the silica coating film coats the inorganic phosphor particles.

The inorganic phosphor particles are preferably completely coated to the extent that the effect of the present invention can be obtained, but the inorganic phosphor particles are not necessarily completely coated.

The silicon oxide film is not particularly limited as long as it is a silicon oxide film, and may be appropriately selected according to the purpose. Further, when the molar ratio of oxygen atoms to silicon atoms in the silicon oxide film is measured by ICP emission spectrometry as described above, the molar ratio (O/Si) is different from that of SiO₂2.00 of the theoretical ratio of (a). In this respect, the molar ratio of oxygen atoms to silicon atoms (O/Si) of the above-described silicon oxide film in the present invention is not necessarily 2.00.

The average thickness of the silicon oxide film is not particularly limited, and may be appropriately selected according to the purpose, and is preferably 3nm to 200nm, more preferably 3nm to 100nm, still more preferably 10nm to 50nm, and particularly preferably 10nm to 30 nm.

The average thickness can be determined, for example, by observing the cross section of the coated phosphor with a scanning or transmission electron microscope and measuring the thickness of the silicon oxide film at any 10 points.

The silicon oxide film may contain other components within limits that can achieve the object of the present invention. In the case where the silicon oxide film contains other components, the molar ratio (O/Si) is calculated as a molar ratio (O/Si) of Si to O of the silicon oxide in the silicon oxide film.

The method for forming the silicon oxide coating is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include a coating step in the method for producing a coated phosphor of the present invention, which will be described later.

The maximum emission wavelength of the coated phosphor is not particularly limited, and may be appropriately selected according to the purpose, and is preferably 500nm to 600 nm.

The average particle size of the coated phosphor is not particularly limited and may be appropriately selected according to the purpose, but is preferably 0.5 μm or more and 30 μm or less, more preferably 1 μm or more and 20 μm or less, and particularly preferably 3 μm or more and 15 μm or less.

The average particle diameter can be measured by a laser diffraction particle size distribution meter (for example, L A-960 manufactured by HORIBA).

The particle diameter D90 of the coated phosphor is not particularly limited and may be appropriately selected according to the purpose, but is preferably 40 μm or less, more preferably 3 μm or more and 30 μm or less, and particularly preferably 5 μm or more and 25 μm or less.

Here, D90 represents a particle size value at which the cumulative value in the particle size distribution of the particles is 90%.

(method for producing coated phosphor)

The method for producing a coated phosphor of the present invention includes at least a coating step and a heating step, and further includes other steps as necessary.

< coating Process >

The coating step is not particularly limited as long as it is a step of forming a silicon oxide coating on the surface of the inorganic phosphor particles to obtain a coated phosphor, and may be appropriately selected according to the purpose, and for example, the following treatments may be performed: a treatment of immersing the inorganic phosphor particles in a liquid containing a silicon oxide precursor; and a process of heating the inorganic phosphor particles having the silicon oxide precursor attached to the surface thereof. These treatments may be the so-called hydrolysis of alkoxysilanes (sol-gel process).

Examples of the silica precursor include alkoxysilanes.

The alkoxysilane may be selected from, for example, ethoxide, methoxide, isopropoxide, and the like, and examples thereof include tetraethoxysilane and tetramethoxysilane. The alkoxysilane may be an alkoxysilane oligomer such as polyethyl silicate or a hydrolysis condensate. The alkoxysilane may be a silane coupling agent having an alkyl group, an amino group, a mercapto group, or the like, which does not contribute to the sol-gel reaction, such as alkylalkoxysilane.

The liquid may contain a solvent. Examples of the solvent include water and organic solvents.

Examples of the organic solvent include alcohols, ethers, ketones, and polyhydric alcohols. Examples of the alcohol include methanol, ethanol, propanol, and pentanol. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, and diethylene glycol.

In addition, a combination of two or more of the solvents may be used.

The formation of the silicon oxide film in the coating step may be performed using a catalyst.

In the case where the silica precursor is the alkoxysilane, the catalyst is a substance for initiating a hydrolysis or polycondensation reaction of the alkoxysilane, and an acidic catalyst or a basic catalyst, for example, can be used. Examples of the acidic catalyst include: hydrochloric acid, sulfuric acid, boric acid, nitric acid, perchloric acid, tetrafluoroboric acid, hexafluoroarsenic acid, hydrobromic acid, acetic acid, oxalic acid, methanesulfonic acid, and the like. Examples of the basic catalyst include: hydroxides of alkali metals such as sodium hydroxide, and ammonia. Among these catalysts, a basic catalyst is preferably used from the viewpoint of effectively preventing deterioration of the inorganic phosphor particles. Two or more of these acidic catalysts and basic catalysts may be used in combination as the catalyst.

< heating Process >

The heating step is not particularly limited as long as it is a step of heating the coated phosphor at a temperature exceeding the temperature at which the silicon oxide film is formed and in an inert atmosphere, and may be appropriately selected according to the purpose.

The temperature for forming the silicon oxide film may be, for example, 300 ℃ or lower, or may be 100 to 250 ℃.

The lower limit of the heating temperature in the heating step is not particularly limited as long as it is a temperature exceeding the temperature at which the silicon oxide film is formed, and may be appropriately selected according to the purpose, and for example, the heating temperature may be 500 ℃ or higher, or 550 ℃ or higher.

The upper limit of the heating temperature is not particularly limited and may be appropriately selected according to the purpose, and the heating temperature is preferably 1200 ℃ or less, more preferably less than 1000 ℃, and particularly preferably less than 900 ℃ from the viewpoint of preventing aggregation of the silicon oxide film.

Examples of the inert atmosphere include a nitrogen atmosphere.

It is considered that the above-mentioned silicon oxide film becomes dense by performing the above-mentioned heating step, and as a result, it is considered that a coated phosphor having excellent stability under high temperature and high humidity in the L ED lit state can be obtained.

(phosphor sheet)

The phosphor sheet of the present invention contains at least the coated phosphor of the present invention, preferably contains a resin, and further contains other components as necessary.

The phosphor sheet can be obtained, for example, by applying a phosphor-containing resin composition (so-called phosphor coating) containing the coated phosphor and a resin onto a transparent base material.

The thickness of the phosphor sheet is not particularly limited, and may be appropriately selected according to the purpose.

The content of the coated phosphor in the phosphor sheet is not particularly limited, and may be appropriately selected according to the purpose.

< resin >

The resin is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: thermoplastic resins, photocurable resins, and the like.

Thermoplastic resin

The thermoplastic resin is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: hydrogenated styrenic copolymers, acrylic copolymers, and the like.

The hydrogenated styrenic copolymer is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: hydrogenated products of styrene-ethylene-butylene-styrene block copolymers, and the like.

The proportion of the styrene unit in the styrene-ethylene-butylene-styrene block copolymer is not particularly limited, and may be appropriately selected depending on the purpose, and is preferably 20 to 30 mol%.

The acrylic copolymer is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: and block copolymers of Methyl Methacrylate (MMA) and Butyl Acrylate (BA). When the fluorescent material is a sulfide, the thermoplastic resin is preferably a hydrogenated styrene copolymer as compared with an acrylic copolymer.

Photocurable resin

The photocurable resin is prepared using a photocurable compound.

The photocurable compound is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: and photocurable (meth) acrylates such as urethane (meth) acrylates. The urethane (meth) acrylate is obtained by, for example, esterifying an isocyanate group-containing product obtained by reacting a polyol with a polyisocyanate (e.g., isophorone diisocyanate) with a hydroxyalkyl (meth) acrylate (e.g., 2-hydroxypropyl acrylate).

The content of the urethane (meth) acrylate in 100 parts by mass of the photocurable (meth) acrylate is not particularly limited, and may be appropriately selected according to the purpose, and is preferably 10 parts by mass or more.

Resin composition

The resin composition containing the resin preferably contains either a polyolefin copolymer component or a photocurable (meth) acrylic resin component.

The polyolefin copolymer is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include styrene copolymers and hydrogenated products of styrene copolymers.

The styrene-based copolymer is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: styrene-ethylene-butylene-styrene block copolymers, styrene-ethylene-propylene block copolymers, and the like. Among them, a hydrogenated product of a styrene-ethylene-butylene-styrene block copolymer is preferable in terms of transparency and gas barrier properties. By containing the above polyolefin copolymer component, excellent light resistance and low water absorption can be obtained.

The content of the styrene unit in the hydrogenated styrene-based copolymer is preferably 10 to 70% by mass, more preferably 20 to 30% by mass, because the content tends to decrease the mechanical strength when the content is too low and to become brittle when the content is too high. If the hydrogenation ratio of the hydrogenated styrene-based copolymer is too low, the weather resistance tends to be poor, and it is preferably 50% or more, more preferably 95% or more.

The photocurable acrylate resin component is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and the like. Among them, urethane (meth) acrylates are preferable from the viewpoint of heat resistance after photocuring. By containing such a photocurable (meth) acrylate resin component, excellent light resistance and low water absorption can be obtained.

In addition, in the phosphor sheet, particles (diffusing material) of an inorganic substance or the like having very little light absorption can be added as needed, and when the refractive index of the sealing material is different from that of the added particles, the particles diffuse (scatter) the excitation light, thereby making it possible to increase the absorption of the excitation light by the coated phosphor, and therefore the amount of the added coated phosphor can be reduced.

< transparent substrate >

The transparent substrate is not particularly limited, and may be appropriately selected according to the purpose, and includes: thermoplastic resin films, thermosetting resin films, photocurable resin films, and the like (Japanese patent application laid-open Nos. 2011-13567, 2013-32515, and 2015-967).

The material of the transparent substrate is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include: polyester films such as polyethylene terephthalate (PET) films and polyethylene naphthalate (PEN) films; a polyamide film; a polyimide film; a polysulfone membrane; cellulose triacetate films; a polyolefin film; polycarbonate (PC) films; a Polystyrene (PS) film; polyethersulfone (PES) membranes; a cyclic amorphous polyolefin film; a multifunctional acrylate film; a multifunctional polyolefin film; an unsaturated polyester film; an epoxy film; and fluororesin films such as PVDF, FEP, and PFA. These base materials may be used alone or in combination of two or more.

Among them, a polyethylene terephthalate (PET) film and a polyethylene naphthalate (PEN) film are particularly preferable.

In order to improve the adhesion to the phosphor-containing resin composition, the surface of such a film may be subjected to corona discharge treatment, silane coupling agent treatment, or the like, as necessary.

The thickness of the transparent substrate is not particularly limited, and may be appropriately selected according to the purpose, and is preferably 10 to 100 μm.

In addition, the transparent base material is preferably a water vapor barrier film in terms of reducing hydrolysis of the inorganic phosphor particles.

The water vapor barrier film is a gas barrier film formed by forming a thin film of a metal oxide such as aluminum oxide, magnesium oxide, or silicon oxide on the surface of a plastic substrate or film such as PET (polyethylene terephthalate). In addition, PET/SiO may be used_xPET and the like.

The water vapor permeability of the barrier film is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 0.05g/m²5 g/m/day²About a day (e.g., 0.1 g/m)²Lower barrier performance on the order of a day). Within such a range, the intrusion of water vapor can be suppressed, and the phosphor sheet can be protected from the water vapor.

Here, an example of the phosphor sheet will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of the structure of an end portion of a phosphor sheet. The phosphor layer 11 of the phosphor sheet is sandwiched between the 1 st water vapor barrier film 12 and the 2 nd water vapor barrier film 13.

The phosphor layer 11 is composed of the coated phosphor of the present invention and a resin, and the coated phosphor is dispersed in the resin.

In the phosphor sheet of FIG. 1, the end portions of the 1 st water vapor barrier film 12 and the 2 nd water vapor barrier film 13 are preferably formed to have a thickness of 1g/m²The covering member 14 having a water vapor permeability of less than one day is sealed.

As the covering member 14, a member having a thickness of 1g/m can be used²An adhesive tape having an adhesive 142 coated on a substrate 141 having a water vapor permeability of less than one day. As the substrate 141, a metal foil such as aluminum foil or water can be usedVapor barrier films 12, 13. Any of glossy white aluminum and matte black aluminum may be used for the aluminum foil, and when a good color tone is required at the end of the phosphor sheet, white aluminum is preferably used. The width W of the covering member 14 attached to the water vapor barrier film is preferably 1mm to 10mm, more preferably 1mm to 5mm, from the viewpoint of water vapor barrier property and strength. According to the covering member 14 including such a configuration, it is possible to prevent water vapor from entering the phosphor layer from the end of the water vapor barrier film, and to prevent deterioration of the phosphor in the phosphor layer.

(light-emitting device)

The light-emitting device of the present invention includes at least the phosphor sheet of the present invention and, if necessary, other members.

An example of a light-emitting device of the present invention will be described with reference to the drawings.

Fig. 2 is a schematic cross-sectional view showing an edge light type light emitting device, and as shown in fig. 2, the light emitting device constitutes a so-called "edge light type backlight" and includes a blue L ED31, a light guide plate 32 for diffusing blue light of a blue L ED31 incident from a side surface and emitting uniform light to a surface, a phosphor sheet 33 for obtaining white light from the blue light, and an optical film 34.

The blue L ED31 constitutes a so-called "L ED package" having, for example, InGaN-based L ED chips as blue light emitting elements, the light guide plate 32 uniformly ground-emits light entering from an end face of a transparent substrate such as an acrylic plate, the phosphor sheet 33 is, for example, a phosphor sheet shown in FIG. 1, the phosphor sheet 33 contains phosphor powder having an average particle diameter of several μm to several tens μm, and thereby the light scattering effect of the phosphor sheet 33 can be improved, and the optical film 34 is, for example, composed of a reflective polarizing film, a diffusion film, or the like for improving the visibility of a liquid crystal display device.

As shown in fig. 3, the light emitting device constitutes a so-called "direct backlight" and includes a substrate 42 on which a blue light L ED41 is two-dimensionally arranged, a diffuser plate 43 for diffusing blue light of the blue light L ED41, a phosphor sheet 33 arranged to be spaced from the substrate 42 and obtaining white light from the blue light, and an optical film 34.

Blue L ED41 constitutes a so-called "L ED package" having, for example, an InGaN-based L ED chip as a blue light emitting element, a substrate 42 is made of a glass cloth substrate using a resin such as a phenol resin, an epoxy resin, or a polyimide, and blue L ED41 is two-dimensionally arranged at a predetermined pitch so as to correspond to the entire surface of a phosphor sheet 33, and a mounting surface of blue L ED41 on the substrate 42 is subjected to a reflection treatment as necessary, the substrate 42 and the phosphor sheet 33 are arranged at a distance of about 10 to 50mm, and a light emitting device constitutes a so-called "remote phosphor structure", a gap between the substrate 42 and the phosphor sheet 33 is held by a plurality of support columns or reflection plates provided so as to surround a space formed by the substrate 42 and the phosphor sheet 33 from the periphery, and a diffusion plate 43 diffuses a light from the blue L ED41 to a large extent that the light cannot be seen in the shape of a light source, and has a total light transmittance of, for example, 20% or more and 80% or less.

The present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention. For example, although the light-emitting device is applied to the backlight light source for the display device in the above-described embodiment, the light-emitting device may be applied to the light source for illumination. When applied to a light source for illumination, the optical film 34 is not required in many cases. The phosphor-containing resin may have a three-dimensional shape such as a cup shape, as well as a planar sheet shape.