Light-emitting device, light-reflecting resin composition, and method for manufacturing the same

Abstract

To provide a light-reflecting member in which the reflectance of white pigment particles is improved by inorganic particles, and the fluidity of the resin can be maintained in an uncured state.SOLUTION: A reflective member includes a transparent resin, and white pigment particles and inorganic particles dispersed in the transparent resin. The white pigment particles have a refractive index greater than that of the transparent resin and a particle size equal to or less than the wavelength of light. The inorganic particles have a refractive index smaller than that of the transparent resin and a particle size smaller than that of the white pigment particles. The inorganic particles are unevenly distributed within a predetermined distance from the surface of the white pigment particles.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light-emitting device in which a reflective member is formed using a light-reflective resin composition. [Background technology]

[0002] BACKGROUND ART Light-reflective resin compositions are known that reflect light emitted from light-emitting diodes (LEDs) with high reflectance, thereby realizing high-brightness light-emitting devices.

[0003] For example, Patent Document 1 discloses a light-reflecting thermosetting resin composition in which a white pigment (particle size 0.05 to 10 μm) such as titanium oxide and inorganic hollow particles (1 to 100 μm) as an inorganic filler are dispersed in 100 parts by mass of a transparent resin. The inorganic filler is used for the purpose of improving the moldability of the resin. Examples of white pigments include alumina oxide, titanium oxide, and zirconium oxide. The content of the inorganic hollow particles as an inorganic filler is 10 to 200 parts by mass relative to 100 parts by mass of the epoxy resin.

[0004] Patent Document 2 discloses a light-reflecting substrate in which a resin composition containing a white inorganic pigment and an inorganic filler such as hollow silica for improving adhesion to the substrate is laminated on the substrate and then thermally cured. The content of the inorganic filler is 1% by mass or more and 70% by mass or less, based on 100% by mass of the nonvolatile components of the resin composition. The total content of the white inorganic pigment and the inorganic filler is 20% by mass or more and 90% by mass or less, based on 100% by mass of the nonvolatile components of the resin composition. The mass ratio of the inorganic filler to the white inorganic pigment is 0.1 or more and 1.5 or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-053019 [Patent Document 2] Japanese Patent Publication No. 2022-047123 Summary of the Invention [Problem to be solved by the invention]

[0006] The resin composition of Patent Document 1 contains a large amount of white pigment and inorganic filler to improve the moldability of the resin in addition to improving reflectance, while the resin composition of Patent Document 2 contains a large amount of white pigment and inorganic filler to improve adhesion to a substrate. For example, the resin composition of Patent Document 1 contains 10 to 200 parts by mass of inorganic filler per 100 parts by mass of epoxy resin. In the resin composition of Patent Document 2, the total content of the white inorganic pigment and inorganic filler is 20% by mass or more and 90% by mass or less, based on 100% by mass of the nonvolatile components of the resin composition. The content of the inorganic filler is 1% by mass or more and 70% by mass or less, based on 100% by mass of the nonvolatile components of the resin composition.

[0007] When a large amount of inorganic filler is added to a resin, the added inorganic filler is prone to agglomeration, and if agglomeration occurs, it becomes difficult to obtain the desired reflective properties. Specifically, the inorganic filler forms aggregates larger than the white inorganic pigment, which is the primary reflective material. This causes the particle concentration in the white resin to become uneven, making it impossible to obtain the desired reflective performance and resulting in variations in reflectance. Furthermore, if inorganic filler aggregates connect to each other to form a light propagation path, the reflective effect of the white resin is reduced. Furthermore, unintended voids may form within the aggregates, which may impair the long-term reliability of products using the white resin composition.

[0008] The aggregation of inorganic fillers becomes significant when nanoparticles with a particle size of 100 nm or less are used as inorganic fillers.

[0009] An object of the present invention is to provide a light-reflecting member in which the reflectance of white pigment particles is improved by the inorganic particles, and the fluidity of the resin can be maintained in an uncured state. [Means for solving the problem]

[0010] In order to achieve the above object, the method for manufacturing a semiconductor light-emitting device of the present invention provides a light-emitting device having a light-emitting element and a reflecting member that reflects light emitted by the light-emitting element, the reflecting member including a transparent resin and white pigment particles and inorganic particles dispersed in the transparent resin. The white pigment particles have a refractive index greater than that of the transparent resin and a particle size equal to or less than the wavelength of light. The inorganic particles have a refractive index smaller than that of the transparent resin and a particle size smaller than that of the white pigment particles. The inorganic particles are present at a higher density within a range within a predetermined distance from the surface of the white pigment particles than in other ranges. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a light-reflective resin composition that improves the reflectance of white pigment particles by using inorganic particles and maintains the fluidity of the resin in an uncured state, and a light-emitting device in which a reflective member is formed using the same. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view of a light emitting device according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing the structure of a reflective member formed from the light-reflective resin composition of the embodiment. [Figure 3] FIG. 2(a) is a diagram showing multiple reflections within a reflecting member formed from a light-reflecting resin composition, and FIG. 2(b) is a diagram explaining scattering of white pigment particles. [Figure 4] FIG. 1 is a diagram for explaining how scattering of white pigment particles changes depending on the refractive index of a transparent resin. [Figure 5] 1 is a flowchart showing a manufacturing process of a light-reflective resin composition of an example. [Figure 6] 1 is a table showing the compositions and reflectances of Examples 1 to 3 and Comparative Examples 1 to 6. [Figure 7] 1 is a cross-sectional photograph of a reflective member formed from the light-reflective resin composition of an example. [Figure 8] 1 is a cross-sectional photograph of a reflective member formed from the light-reflective resin composition of an example. [Figure 9] 3(a) to 3(c) are graphs showing the reflectance for each wavelength of the reflective members formed from the light-reflective resin compositions of Examples 1-3 and Comparative Examples 1-6. [Figure 10] Photograph showing aggregated hollow silica. [Figure 11] 1 is a graph showing the reflectance of a reflective member formed from the light-reflective resin composition of Example 1-3 for each wavelength. [Figure 12] 10 is a graph showing the bleed light (brightness glare) of a light emitting device formed using the light-reflective resin composition of Example 4, for each amount of hollow silica added. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present invention will be described below.

[0014] The reflective member of the present invention is obtained by curing a light-reflective resin composition in which white pigment particles and inorganic particles are added to a transparent resin, and is characterized by the large number of inorganic particles present (distributed unevenly) near the white pigment particles. The refractive index of the inorganic particles is smaller than that of the transparent resin. This structure allows the distributed inorganic particles to reduce the effective refractive index of the transparent resin surrounding the white pigment particles, thereby improving the reflectance of the white pigment particles. Therefore, even if the amount of inorganic particles added is small, the fluidity of the reflective member can be maintained in the uncured state. This will be explained in more detail below.

[0015] The light emitting device of this embodiment has a light emitting element and a reflective member that reflects light emitted by the light emitting element. The positions of the light emitting element and the reflective member may be any arrangement. As an example, a structure such as that shown in FIG. 1 may be used. The light emitting device of FIG. 1 has a light emitting element 10, which has a light emitting layer 12 mounted on an element substrate 11, mounted on a submount substrate 13. A phosphor layer 14 is fixed on top of the light emitting layer 12 by an adhesive layer 15. A reflective member 16 is filled in so as to contact the side surfaces of the light emitting element 10 and the phosphor layer 14. The lower surface and side surfaces of the submount substrate 13 and the outer periphery of the reflective member 16 contact the housing.

[0016] The light emitted upward from the light-emitting layer 12 is partially converted into fluorescence by the phosphor layer 14 and emitted from the upper surface of the phosphor layer 14. The light emitted from the side surface of the light-emitting layer 12 is reflected by the reflecting member 16 and directed upward. The light emitted from the side surface of the phosphor layer 14 is also reflected by the reflecting member 16 and directed upward. This allows light to be efficiently emitted from the upper surface of the phosphor layer 14.

[0017] If the reflectance of the reflective member 16 is low, a portion of the light incident on the reflective member 16 travels within the reflective member 16 and is emitted from the upper surface of the reflective member 16. As a result, a small amount of light is emitted not only from the upper surface of the phosphor layer 14 but also from the upper surface of the reflective member 16. The light emitted from the upper surface of the reflective member 16 is called bleed light, and is undesirable for an optical system that collects light emitted from a light-emitting device. Therefore, in this embodiment, the reflective member 16 is structured as follows to improve the reflectance. Furthermore, the fluidity of the reflective member 16 in its uncured state is maintained, allowing it to be filled into a desired shape, etc.

[0018] As shown in FIG. 2, the reflecting member 16 includes a transparent resin 21, and white pigment particles 22 and inorganic particles 23 dispersed in the transparent resin 21.

[0019] The average particle size of the white pigment particles 22 is equal to or less than the wavelength of light emitted from the light emitting element 10. Furthermore, in the case where the light emitting device of this embodiment has a phosphor layer 14, the average particle size of the white pigment particles 22 is equal to or less than the wavelength of light emitted from the phosphor layer 14. The refractive index of the white pigment particles 22 is higher than the refractive index of the transparent resin 21. In the light emitting device of this embodiment, the average particle size of the white pigment particles 22 is preferably 100 nm or more and 500 nm or less.

[0020] The inorganic particles 23 have a smaller refractive index than the transparent resin 21. The average particle size of the inorganic particles 23 is smaller than the average particle size of the white pigment particles 22. The inorganic particles 23 are unevenly distributed in large numbers within a range of a predetermined distance L from the surface of the white pigment particles 22. That is, the inorganic particles 23 are present at a higher density within the range of the predetermined distance L from the surface of the white pigment particles 22 than in other ranges.

[0021] The average particle size of the white pigment particles and inorganic particles can be determined as the circle equivalent diameter obtained by analyzing a cross-sectional observation image of the reflective member 16 using a transmission electron microscope (TEM), or as the volume average calculated from the particle size distribution obtained by a laser diffraction / scattering method for the particles before addition.

[0022] In this way, by distributing inorganic particles 23 having a refractive index smaller than that of the transparent resin 21 unevenly within the range of distance L from the surface of the white pigment particles 22, the average refractive index within the range of distance L from the surface of the white pigment particles 22 can be made lower than that of the transparent resin 21. This makes it possible to improve the rate at which Rayleigh scattering occurs in the white pigment particles 22, even with a small amount of inorganic particles 23 added. Compared to Mie scattering, Rayleigh scattering causes backscattering in the inorganic particles 23 with higher efficiency, and therefore can increase the reflectance of the white pigment particles 22. The improvement in the rate of Rayleigh scattering will be explained in more detail later.

[0023] The predetermined distance L is preferably approximately the wavelength of the light emitted from the light-emitting element 10 (the light to be reflected) in the translucent resin. If the wavelength of the light from the light-emitting element 10 is blue, the distance L is preferably 300 nm or more and 400 nm or less. Furthermore, if the phosphor layer 14 is provided, the predetermined distance L is preferably approximately the wavelength of the light emitted from the phosphor layer 14 in the translucent resin. For example, if the light emitted from the phosphor layer 14 is yellow, the distance L is preferably 300 nm or more and 460 nm or less. If the distance L is shorter than the wavelength of the light to be reflected, the refractive index of the light within the range of the distance L from the surface of the white pigment particles 22 cannot be sufficiently reduced. If the distance L is too longer than the wavelength of the light to be reflected, the fluidity of the uncured reflective member will be reduced.

[0024] It is preferable that 80% or more of the inorganic particles 23 in the reflecting member 16 are present within the range of the distance L.

[0025] It is preferable to use hollow particles or porous particles as the inorganic particles 23 so that the refractive index is lower than that of the transparent resin 21. In this case, the porosity of the inorganic particles 23 is preferably 20% by volume or more. For example, by setting the porosity of hollow silica particles as the inorganic particles 23 to 40%, the refractive index can be set to 1.28, which is lower than the refractive index of solid silica particles, 1.46.

[0026] The average particle size of the inorganic particles 23 is equal to or less than the wavelength of the light to be reflected in the transparent resin 21, and is preferably 20 nm or more and 100 nm or less. As a result, the light to be reflected is mainly reflected by the white pigment particles 22, and the apparent refractive index of the transparent resin 21 in the vicinity of the white pigment particles 22 decreases, thereby improving the reflectance of the white pigment particles 22.

[0027] The content of the white pigment particles 22 in the reflecting member 16 is preferably 5% by volume or more and 20% by volume or less, and the content of the inorganic particles 23 is preferably 3% by volume or more and 10% by volume or less.

[0028] By setting the content of inorganic particles 23 in the reflective member 16 to 3% by volume or more and 10% by volume or less, aggregation of white pigment particles can be suppressed, and the phenomenon in which the viscosity of the uncured reflective member 16 increases and its fluidity deteriorates can be suppressed.

[0029] Furthermore, by setting the content of the white pigment particles 22 in the reflective member 16 to 5% by volume or more and 20% by volume or less, more preferably 5% by volume or more and 15% by volume or less, it is possible to form a region with a high density of inorganic particles within a predetermined range from the surface of the white pigment particles 22, and to form a region with a low density of inorganic particles outside of that.

[0030] 1, the light emitting element 10 and the reflecting member 16 are in contact with each other, but they may be disposed apart. For example, a structure may be adopted in which the light emitting element 10 is disposed on the end face of the light guide plate, and the reflecting member 16 is disposed in a layer on the side face of the light guide plate.

[0031] The white pigment particles 22 and the inorganic particles 23 may contain a surface treatment agent that modifies the particle surface.

[0032] The transparent resin 21 may be epoxy, silicone, polyurethane, or the like.

[0033] Furthermore, the white pigment particles 22 can be particles made of metal oxides such as aluminum oxide, titanium oxide, zirconium oxide, and alumina. The white pigment particles 22 are particles made of metal oxides and have light scattering properties. The white pigment particles 22 can be made of one type of particles made of these metal oxides or a mixture of two or more types of particles. These white pigment particles 22 have a refractive index at least higher than that of the transparent resin 21. Furthermore, since the white pigment particles 22 have a refractive index higher than that of the transparent resin 21, they have high light scattering properties, so they are preferably solid particles.

[0034] The inorganic particles 23 may be hollow particles having an outer shell primarily composed of titanium oxide or silicon oxide and an internal void structure. Porous particles may also be used as the inorganic particles 23. The inorganic particles 23 are preferably nanoparticles with an average particle size of 100 nm or less, from the viewpoint of ensuring that the inorganic particles 23 are present in the vicinity of the white pigment particles 22, and more preferably 60 nm or less. In particular, when hollow inorganic particles 23 are used, the average particle size is preferably one-third or less, and even more preferably one-quarter or less, of the average particle size of the white pigment particles 22. The apparent refractive index of hollow particles decreases as the proportion of internal voids increases. Here, the hollow inorganic particles 23 have a refractive index at least lower than that of the transparent resin 21.

[0035] <Principle of improving reflectivity> 3(a), in a transparent resin 21 containing white pigment particles 22, incident light is scattered by the white pigment particles 22, and this occurs continuously (=multiple scattering), resulting in a reflective effect. Therefore, the reflectance of the resin can be improved by controlling the light scattering caused by the white pigment particles 22.

[0036] A typical model of the distribution of light scattering intensity by a microparticle is shown in Figure 3(b). The scattering behavior of light changes depending on conditions such as the medium, particle shape, size, refractive index, and light wavelength. The scattering of light toward the light incident side (backscattering) increases as the scattering approaches Rayleigh scattering rather than Mie scattering.

[0037] Therefore, in the case of a white resin that uses multiple scattering, increasing back scattering is effective in improving reflectance.

[0038] Therefore, in this embodiment, the refractive index of the medium around the white pigment particles 22 is reduced by the inorganic particles 23, thereby increasing backscattering.

[0039] Figure 4 shows the calculation results of the angular distribution of scattering intensity when silicone resins with various refractive indices are used as the transparent resin 21 and titania particles are used as the white pigment particles 22. The calculation was performed assuming that the titania particles were 250 nm spherical particles and the wavelength of the incident light was 550 nm (in air).

[0040] As is clear from FIG. 4, in silicone with a refractive index n=1.425, incident light is strongly scattered forward by titania particles, but as the refractive index of silicone is reduced, the proportion of backscattering increases.

[0041] This shows that by decreasing the refractive index of the transparent resin 21 around the white pigment particles 22, backscattering is increased and the reflectance of the reflective member 16 is improved.

[0042] In this embodiment, to reduce the refractive index of the transparent resin 21, inorganic particles 23 having a lower refractive index than the transparent resin 21 are dispersed in the transparent resin 21. Instead of uniformly dispersing the inorganic particles 23 throughout the transparent resin 21, the inorganic particles 23 are unevenly distributed within a distance L from the surface of the white pigment particles 22. The distance L is approximately the wavelength of the light to be reflected in the transparent resin 21. The refractive index of the medium within the distance L from the surface of the white pigment particles 22 can be approximated as the average value of the refractive index of the transparent resin 21 and the refractive index of the inorganic particles 23. Therefore, by distributing the inorganic particles 23 within the distance L from the surface of the white pigment particles 22, the apparent refractive index of the transparent resin 21 as seen from the white pigment particles 22 can be reduced. Furthermore, by unevenly distributing the inorganic particles 23 within the distance L from the surface of the white pigment particles 22 rather than uniformly dispersing them throughout the transparent resin 21, the amount of inorganic particles 23 present outside the distance L is less than within the distance L, thereby maintaining the fluidity of the uncured reflective member 16.

[0043] The distance L over which the inorganic particles 23 are present at a high density can provide a refractive index reduction effect even if it is the distance over which one inorganic particle 23 is present, but it is preferable that the distance L be greater than this.

[0044] When a blue LED is used as the light-emitting element 10 and converted into yellow fluorescence by the phosphor layer 14, and white light (wavelength range: 450 to 650 nm) is emitted from the phosphor layer 14, the wavelength of this light propagating through the silicone (refractive index: 1.41) used as the transparent resin 21 is 320 to 460 nm. Furthermore, the wavelength range of the fluorescent light (yellow light) propagating through the silicone (refractive index: 1.41) is 360 to 460 nm. Therefore, the distance L from the surface of the white pigment particles 22 (e.g., titania) is preferably 300 nm to 500 nm. In particular, considering the fluidity of the reflective member 16 when uncured, it is preferably 300 nm or less. If a large number of low-refractive-index hollow particles are present within this range of distance L, the difference in refractive index between the transparent resin 21 and the white pigment particles 22 increases, thereby increasing backscattering. Preferably, 80% or more of the inorganic particles 23 are present within the range of distance L. [Example]

[0045] An example of a method for producing a light-reflecting resin composition that forms the reflecting member 16 of the above-described embodiment will be described with reference to FIG. In this embodiment, a two-component transparent resin 21 made by mixing a base agent and a curing agent is used to manufacture a light-reflecting resin composition.

[0046] As shown in Fig. 5, surface-treated white pigment particles 22 were added and dispersed in the main component of two-component transparent resin 21, and then inorganic particles 23 were added and mixed in an organic solvent. After that, a curing agent was mixed into the main component and stirred to produce a light-reflective resin composition in which inorganic particles 23 were unevenly distributed within a distance L from the surface of white pigment particles 22. This light-reflective resin composition was applied or filled into a desired shape and cured by heating to produce reflective member 16.

[0047] <Examples 1 to 4> Specific manufacturing steps of Examples 1 to 6 will be described with reference to FIG.

[0048] Two-component transparent silicone was prepared as the transparent resin 21, titania (average particle size 250 nm) as the white pigment particles 22, and hollow silica (average particle size 60 nm) as the inorganic particles 23, as shown in Table 1. LPS-2419A / B manufactured by Shin-Etsu Chemical Co., Ltd. was used as the silicone resin, and CR-90-2 manufactured by Ishihara Sangyo Kaisha, Ltd. was used as the titania. Hollow silica with an average particle size of 60 nm and a porosity of 45% was used. <Process 501> Titania that had been surface-treated with a silane coupling agent was added to a two-component transparent silicone base material that was the transparent resin 21, and the mixture was stirred. This resulted in the titania being uniformly dispersed in the transparent silicone base material.

[0049] In Examples 1 to 3, the amount of titania added was set to 9 vol % with respect to the reflective resin composition completed in step 504, as shown in FIG.

[0050] <Process 502> Next, the hollow silica prepared as inorganic particles 23 was in a state of being dispersed in a solvent (PGMEA (propylene glycol methyl ether acetate) (hollow silica solution), so the solvent was dried and the hollow silica was extracted (powdered).

[0051] In step 501, the hollow silica was added to the transparent silicone base material in which the titania was dispersed and stirred.

[0052] In Examples 1 to 3, the amount of hollow silica added was set to 11 vol % with respect to the reflective resin composition completed in step 504, as shown in FIG.

[0053] <Process 503> The dispersion of titania and hollow silica in a transparent silicone base material produced in step 502 was diluted with an organic solvent (acetone), and then subjected to high-pressure atomization to disperse and emulsify the titania and hollow silica aggregates. The high-pressure atomization was performed using a wet milling device called Starburst manufactured by Sugino Machine Co., Ltd.

[0054] By adding hollow silica powder to silicone in which titania has already been dispersed and then subjecting the mixture to high-pressure atomization in a dilution solvent, the nano-sized hollow silica particles can be dispersed near the titania without self-aggregation.

[0055] <Process 504> A transparent silicone curing agent was added to the silicone base material in which titania and hollow silica were dispersed, and the mixture was stirred and degassed under vacuum to remove the organic solvent and knead the mixture.

[0056] As a result, a light-reflecting resin composition was produced in which the hollow silica particles were unevenly distributed within a range of a distance L from the surface of the titania.

[0057] The light-reflecting resin composition thus produced was applied to a glass substrate by a squeegee method to a uniform thickness, and then cured by heating to prepare a white resin layer sample. The thicknesses of the white resin layer in Examples 1 to 3 were 0.05, 0.08, and 0.18 mm, respectively.

[0058] <Comparative Examples 1 to 3> As shown in FIG. 6, the light-reflective resin compositions of Comparative Examples 1 to 3 were produced without carrying out step 502 of adding hollow silica and high-pressure atomization treatment step 503.

[0059] The light-reflecting resin composition thus produced was applied to a glass substrate by a squeegee method to a uniform thickness, and then cured by heating to prepare white resin layer samples. The thicknesses of the white resin layer in Comparative Examples 1 to 3 were 0.045, 0.087, and 0.157 mm, respectively.

[0060] <Comparative Examples 4 to 6> In Comparative Examples 4 to 6, the amount of hollow silica added in step 502 was 20 vol% relative to the reflective resin composition completed in step 504, and the other steps were the same as in Examples 1 to 3 to produce light-reflective resin compositions.

[0061] The light-reflecting resin composition thus produced was applied to a glass substrate by a squeegee method to a uniform thickness, and then cured by heating to prepare white resin layer samples. The thicknesses of the white resin layer in Comparative Examples 4 to 6 were 0.101, 0.152, and 0.146 mm, respectively.

[0062] <Comparative Example 7> In Comparative Example 7, titania was dispersed in a silicone base material, and hollow silica was dispersed in a secondary material, and then the two were mixed.

[0063] The method of Comparative Example 7 failed to allow hollow silica to be unevenly distributed around the titania particles.

[0064] <Rating 1> Fig. 7 shows a TEM (transmission electron microscope) observation of a 100 nm thick section of a reflective member 16 produced by heat-curing a light-reflecting composition produced under the same conditions as in Examples 1 to 3, which was processed by cryosectioning with a Leica ultramicrotome. In Fig. 7, the dotted circle indicates the range of a distance L = 300 nm from the surface of the white pigment particle 22 (titania).

[0065] FIG. 8 shows the results of counting inorganic particles 23 (hollow silica) present in the 4.2×3.5 μm observation field of the observation image of FIG. 7, which are present within a range of 300 nm or less from the white pigment particles 22 (titania).

[0066] As shown in Figure 8, it was confirmed that 383 particles (87%) of the 440 inorganic particles 23 (hollow silica) present in the observation field were present within 300 nm of the white pigment particles 22 (titania).

[0067] To improve reflectance, it is considered desirable that 80% or more of the hollow particles be in the 0.3 μm range, and more preferably 90% or more be in the 0.3 μm range.

[0068] <Rating 2> The reflectance of the white resin layers of Examples 1 to 3 and Comparative Examples 1 to 6 was measured for light with wavelengths of 450 nm to 650 nm. Measurements were performed using a spectrophotometer UH415 manufactured by Hitachi High-Tech Science Corp. The results are shown in Figures 9(a) to 9(c).

[0069] It was confirmed that the reflectance was improved in Examples 1 to 3 in which 11 vol % of inorganic particles 23 (hollow silica) was added, compared with Comparative Examples 1 to 3 in which no inorganic particles 23 (hollow silica) were contained.

[0070] On the other hand, in Comparative Examples 4 to 6, in which hollow silica particles were added up to 20 vol%, a tendency for the reflectance to decrease was confirmed. This is thought to be because the amount of hollow silica added was large, causing the hollow silica particles to continuously aggregate, as shown in Figure 10. When hollow silica particles with a low refractive index continuously aggregate, light is more likely to propagate through the continuous aggregates, resulting in a decrease in reflectance.

[0071] 11 shows the reflectance of the white resin layer for wavelengths of 450 nm to 650 nm in Examples 1 to 3. It was confirmed that the thicker the white resin layer, the higher the reflectance.

[0072] Example 4 Light-reflecting resin compositions were produced with hollow silica added in amounts of 3 vol%, 5 vol%, 8 vol%, 10 vol%, and 12 vol% using the manufacturing methods of Examples 1 to 3. The light-reflecting resin compositions produced were used to form the reflecting members 16 in Fig. 1, and light-emitting devices were produced.

[0073] Of the light incident on the reflecting member 16 from the phosphor layer 14, the light that is not reflected by the white pigment particles 22 of the reflecting member 16 propagates within the reflecting member 16 and becomes blurred light that is emitted from the upper surface.

[0074] To measure the bleed light, the front luminance distribution of each manufactured light-emitting device was measured. The measurements were performed using a Prometric I series from Radiant Vision System. The bleed light (luminance glare) was calculated as the ratio (B / A (%)) of the front luminance (B) of the reflective member 16 at a position 0.2 mm from the edge of the phosphor layer 14 to the luminance (A) at the center of the phosphor layer 14. The results are shown in Figure 12.

[0075] FIG. 12 also shows the measurement results of the bleed light (luminance glare) of a light emitting device manufactured using the light-reflective resin composition of Comparative Example 1, which does not contain hollow silica.

[0076] As is clear from Figure 12, it was confirmed that when the amount of hollow silica added was in the range of 3 to 10%, the amount of light bleed from the reflective member 16 was reduced compared to the light-emitting device manufactured using the light-reflective resin composition of Comparative Example 1.

[0077] On the other hand, as the amount added increased, the amount of blurred light tended to increase.

[0078] For these reasons, it is believed that the optimum amount of hollow silica to be added varies depending on the particle shape, amount, concentration, and dispersion method.

[0079] <Effects> As described above, by adding a small amount of inorganic particles 23 (hollow silica), a light-reflective resin composition with high reflectance can be realized, and bleeding light from the light-emitting device can be reduced. [Explanation of symbols]

[0080] 10 Light-emitting element 11 Element substrate 12. Emitting layer 13 Submount substrate 14 Phosphor layer 15 Adhesive layer 16 Reflective material 17. Housing 21 Transparent resin 22 White pigment particles 23 Inorganic particles

Claims

1. A light emitting device having a light emitting element and a reflecting member that reflects light emitted by the light emitting element, the reflective member includes a transparent resin, and white pigment particles and inorganic particles dispersed in the transparent resin; the white pigment particles have a refractive index greater than the refractive index of the transparent resin and a particle size equal to or less than the wavelength of the light in the transparent resin; the inorganic particles have a refractive index smaller than that of the transparent resin and a particle size smaller than that of the white pigment particles; The light-emitting device is characterized in that the inorganic particles are present at a higher density within a range within a predetermined distance from the surface of the white pigment particles than in other ranges.

2. 2. The light emitting device according to claim 1, wherein the predetermined distance is equal to or greater than the wavelength of the light in the transparent resin.

3. 2. The light-emitting device according to claim 1, wherein the inorganic particles are hollow particles or porous particles.

4. 4. The light-emitting device according to claim 3, wherein the porosity of the inorganic particles is 20% by volume or more.

5. 2. The light emitting device according to claim 1, wherein the inorganic particles have an average particle size of 20 nm or more and 100 nm or less.

6. 6. The light emitting device according to claim 5, wherein the average particle size of the inorganic particles is one-third or less of the average particle size of the white pigment particles.

7. 2. The light-emitting device according to claim 1, wherein the content of the white pigment particles in the reflective member is 5% by volume or more and 20% by volume or less, and the content of the inorganic particles is 3% by volume or more and 10% by volume or less.

8. 2. The light-emitting device according to claim 1, further comprising a phosphor layer disposed at a position where light emitted from the light-emitting element is incident, the light-emitting element is a blue light-emitting element, and the phosphor layer includes a fluorescent member that converts a part of the light emitted by the light-emitting element into yellow light; The light-emitting device is characterized in that 80% or more of the inorganic particles are unevenly distributed within a range of a distance of 300 nm from the surface of the white pigment particle.

9. A light-reflective resin composition comprising a transparent resin, and white pigment particles and inorganic particles dispersed in the transparent resin, the particle size of the white pigment particles is equal to or smaller than the wavelength of light to be reflected, the inorganic particles have a refractive index smaller than that of the transparent resin and a particle size smaller than that of the white pigment particles; The inorganic particles are present at a higher density in a range within a predetermined distance from the surface of the white pigment particle than in other ranges. A light-reflecting resin composition comprising:

10. A method for producing a light-reflective resin composition, comprising: A step of dispersing white pigment particles and inorganic particles in a two-component transparent resin base material obtained by mixing a base material and a curing agent; mixing the curing agent with the base resin in which the white pigment particles and inorganic particles are dispersed to produce the uncured transparent resin; applying or filling the uncured transparent resin into a desired shape; and curing the transparent resin. the inorganic particles have a refractive index smaller than that of the transparent resin after curing, a particle size smaller than that of the white pigment particles, and a particle size smaller than the wavelength of light to be reflected; the transparent resin has the inorganic particles unevenly distributed in large numbers within a range within a predetermined distance from the surfaces of the white pigment particles, and the uneven distribution of the inorganic particles is maintained even in the cured transparent resin.

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