JP6693360B2 - Light conversion member, illumination light source, and method for manufacturing light conversion member - Google Patents

Description

  The present invention relates to a light conversion member, an illumination light source, and a method for manufacturing the light conversion member, and more particularly to a light conversion member, an illumination light source, and a method for manufacturing the light conversion member that are stable even when many phosphor particles are dispersed.

  The LED is used as a light source for illuminating a small amount of electric power, and is expected to be applied to lighting. At this time, the LED may be used as it is by irradiating its emitted color as it is, but since the emitted color to be obtained is wide-ranging, it is general to use phosphor particles for wavelength-converting the light of the LED.

  For example, white light of a white LED is obtained by synthesizing blue light emitted from a blue LED element serving as a light source and light such as red light in which a part of the blue light is converted in wavelength by phosphor particles. This type of LED has been known in which a blue LED element is coated with a phosphor layer in which a phosphor is dispersed in a transparent resin such as silicone, but the heat resistance and light resistance are insufficient.

  As a light conversion member for obtaining a white illumination light source having a longer life than that of resin, glass powder was used instead of resin, mixed with phosphor powder, and sintered to disperse the phosphor powder in the glass. The thing is known (for example, refer patent document 1).

JP, 2010-132923, A

  By the way, there is a demand for a light conversion member that receives LED light having a high light density and converts almost all the light into a color emitted by a phosphor. By converting almost all LED light in this way, it is possible to extract light having a relatively wide wavelength width due to emission of an arbitrary phosphor with high brightness and suppressing color mixture of LED light.

  However, the luminescent color conversion member of Patent Document 1 is the one specifically shown as an example in which the content of the phosphor powder is suppressed to about 10% by volume, and the transmission of LED light is sufficiently suppressed. It is not something that can be done.

  It should be noted that it is possible to increase the content of the phosphor powder in order to suppress color mixture of the LED light with reference to the above-mentioned Patent Document 1, but if the phosphor particles are contained in a large amount in the glass, sintering will be sufficient. It has been found that there are cases where it is not possible to perform, or there is a case where even if the sintering is sufficiently performed, there is a remarkable decrease in brightness when continued to be used, and an LED illumination light source having excellent quality cannot be obtained.

  Therefore, in view of the above problems, the present invention, even when containing a large amount of phosphor particles, can be sufficiently sintered, it is possible to significantly suppress the decrease in brightness of the converted light in long-term use. An object of the present invention is to provide a light conversion member having excellent water resistance and a good LED light absorption rate, and an illumination light source using the light conversion member.

  As a result of diligent studies by the present inventors, by using glass having a predetermined composition, it is possible to satisfactorily sinter even when the content of phosphor particles is large, and to reduce the brightness of converted light in long-term use. The present invention has been completed, and it has been found that it is possible to suppress the above, and has water resistance that does not easily deteriorate even in an environment with high humidity.

That is, the light conversion member of the present invention is a light conversion member made of glass in which phosphor particles are dispersed, and the glass is SiO ₂ 0 to 40%, B ₂ O in terms of oxide-based mol%. ₃ 10-45%, Al ₂ O ₃ 0-10%, ZnO 25-64%, alkaline earth metal oxide (MgO + CaO + SrO + BaO) 0-30%, alkali metal oxide (Li ₂ O + Na ₂ O + K ₂ O) 0 5%, Bi ₂ O ₃ 0.5% or less, PbO 0.5% or less, and the phosphor particles are contained in the glass in an amount of more than 15% by volume.

  The method for producing a light conversion member of the present invention comprises a kneading step of kneading glass powder, phosphor particles, a resin and an organic solvent to form a slurry, a molding step of molding the obtained slurry into a desired shape, and molding. A method of manufacturing a light conversion member, comprising: a step of baking the slurry to a light conversion member, wherein the light conversion member to be manufactured is the light conversion member of the present invention. ..

  The illumination light source of the present invention is characterized by including the light conversion member of the present invention and a light source capable of irradiating light to the outside through the light conversion member.

  INDUSTRIAL APPLICABILITY As described above, the light conversion member and the method for producing the same according to the present invention can be sufficiently fired to form a light conversion member even when the content of the phosphor particles is large, and provides stable converted light even when used for a long time. It can be a light conversion member that can be irradiated.

  Since the illumination light source of the present invention uses the light conversion member of the present invention, converted light by the phosphor can be stably obtained as described above. This is useful when the light mainly composed of the converted light is used as the irradiation light to the outside, and the irradiation light composed of the light having the desired wavelength can be obtained by selecting the kind of the phosphor particles.

It is sectional drawing which showed schematic structure of the illumination light source which is one Embodiment of this invention. It is sectional drawing which showed schematic structure of the illumination light source which is other embodiment of this invention. It is sectional drawing which showed schematic structure of the illumination light source which is other embodiment of this invention. It is sectional drawing which showed schematic structure of the illumination light source which is other embodiment of this invention.

  Hereinafter, a light conversion member (hereinafter, also referred to as “present light conversion member”), a method for manufacturing the light conversion member, and an illumination light source according to the present invention will be described.

[Light conversion member]
As described above, the light conversion member of the present invention is made of a desired glass containing phosphor particles dispersed therein.

  Here, the glass forming the present light converting member is formed to have a glass composition described below. Such a light conversion member converts the wavelength of the light (light source light) emitted from the light source, and allows the converted light obtained by this conversion to be emitted to the outside. As the light source light, an LED that emits light near blue can be used, and a near-ultraviolet LED (emission center wavelength 350 to 410 nm) may be used, but a blue LED (emission center 420 to 480 nm) having high emission efficiency is preferable. Similarly, a laser light source having the above wavelength is also suitable.

  At this time, a part of the light source light may be transmitted through the light conversion member and irradiated to the outside as a combined light of the light source light and the converted light. May be irradiated to the outside. In particular, the light source light emitted from the near-ultraviolet LED or the blue LED has a short wavelength and deteriorates the resin sealing member, etc., and further dislikes the variation in the emission wavelength of the LED between lots. It is preferable to mainly radiate the converted light to the outside in order to make the design in which variations in degree are suppressed. Further, when using an LED for a direction indicator light of a vehicle such as an automobile, from the viewpoint of safety standards and visibility, the light source light emitted by the blue LED is prevented from being radiated to the outside, and light with a high conversion purity component and high color purity is used. Irradiation to the outside is preferable.

  Here, "mainly irradiate the converted light to the outside" means that the transmitted light of the light source light is 3% or less with respect to the light source light among the light irradiated to the outside from the light conversion member, Further, it is preferably 2% or less, more preferably 1.5% or less, still more preferably 1% or less.

<Glass>
The glass of the present invention is expressed in mol% based on oxide, and is expressed as SiO ₂ 0 to 40%, B ₂ O ₃ 10 to 45%, Al ₂ O ₃ 0 to 10%, ZnO 25 to 64%, alkaline earth metal. oxide (MgO + CaO + SrO + BaO ) 0~30%, alkali metal oxides _{(Li 2 O + Na 2 O} + K 2 O) 0~5%, Bi 2 O 3 0.5% or less, PbO 0.5% or less, having a composition of Is characterized by. Hereinafter, each component of this glass will be described.

SiO ₂ is a glass network former, which can stabilize glass and is also a component that enhances water resistance. In the present invention, SiO ₂ is an optional component, but it is preferable to contain it. The content of SiO ₂ is 0 to 40%. When SiO ₂ exceeds 40%, the sintering temperature is increased, the damage given to the phosphor becomes large, and the sintering becomes difficult, which is not preferable. The content of SiO ₂ is preferably from 5 to 30%, more preferably 5 to 20%.

B ₂ O ₃ is a glass network former, can stabilize glass, and is an essential component. The content of B ₂ O ₃ is 10 to 45%. When the content of B ₂ O ₃ is less than 10%, the glass becomes unstable and is easily crystallized, and the sinterability may be impaired. On the other hand, if the B ₂ O ₃ content exceeds 45%, the water resistance of the glass may decrease. The content of B ₂ O ₃ is preferably 10 to 35%, more preferably 15 to 30%.

Al ₂ O ₃ is a component that improves the water resistance of glass and suppresses crystallization, but is not an essential component in the present invention. It is also a component that suppresses the reaction with the phosphor during firing. The content of Al ₂ O ₃ is 0 to 10%. If the content of Al ₂ O ₃ exceeds 10%, Tg becomes too high and the liquidus temperature rises, so that the sinterability may be impaired. The content of Al ₂ O _3, preferably 0 to 8%, more preferably 0 to 6%.

  ZnO is an essential component because it has the advantages of broadening the vitrification range and increasing the degree of freedom of the glass composition. ZnO is also a component that lowers Tg and lowers the sintering temperature. The content of ZnO is 25 to 64%. When the content of ZnO is less than 25%, the sinterability is lowered in the present invention containing a large amount of phosphor powder, which is not preferable. On the other hand, if the content of ZnO exceeds 64%, the glass becomes unstable and crystallization is likely to occur, possibly impairing the sinterability. 40-64% is preferable and, as for content of ZnO, 45-60% is more preferable.

  Alkaline earth metal oxides of CaO, SrO, MgO and BaO are components that lower the crystallization tendency and increase the stability of the glass and improve the sinterability, but the water resistance tends to be slightly lowered. , Is not an essential ingredient. The content of each of these alkaline earth metal oxide components is 0 to 30%, that is, the content of MgO is 0 to 30%, the content of CaO is 0 to 30%, and the content of SrO is 0 to 30%. The content of BaO is 0 to 30%, and the total amount of these alkaline earth metal oxides is preferably 0 to 30%. If this total amount exceeds 30%, the stability of the glass may decrease, the absorption edge of the glass may shift to the long wavelength side, and the blue light of the LED element may be absorbed.

  The content of the alkaline earth metal oxide is more preferably 15% or less. Further, among the alkaline earth metal oxides, BaO is preferable, and the content of BaO is more preferably 0 to 5%, further preferably 0 to 1%.

The alkali metal oxides of Li ₂ O, Na ₂ O and K ₂ O are components that lower Tg and lower the sintering temperature, and are not essential components in this system. The content of each alkali metal oxide is 0 to 5%, that is, the content of Li ₂ O is 0 to 5%, the content of Na ₂ O is 0 to 5%, and the content of K ₂ O is 0. 5%, and the total amount of these alkali metal oxides is preferably 0 to 5%.

  If the total amount exceeds 5%, the refractive index is lowered, the chemical durability of the glass is lowered, the reaction with the phosphor is promoted during firing, the absorption edge of the glass is shifted to the long wavelength side, and the LED element is produced. May absorb the blue light. This total amount is more preferably 0 to 3%, further preferably 0 to 0.5%. Alkali metal oxides tend to lower the water resistance, so it is preferable not to include them unless there is a particular reason to lower the Tg.

Bi ₂ O ₃ and PbO are components that easily colloid due to the action caused by light or heat, and it is preferable that Bi ₂ O ₃ and PbO are not substantially contained. In the present invention, since a large amount of phosphor particles are contained, it is not preferable that these components are contained, since colloid formation is likely to occur at the interface between the phosphor particles and glass, and the brightness of the light conversion member may be reduced. The term "substantially free from" means that the content is 0.5% or less.

  This glass consists essentially of the above components, but may contain other components within the range not impairing the object of the present invention. When other components are contained, the total amount is preferably 20% or less, more preferably 5% or less, still more preferably 1% or less, and particularly preferably less than 1% in terms of mol% based on the oxide.

P ₂ O ₅ is a glass network former, and is a component that improves water resistance in a small amount and is an optional component in the present invention. The content of P ₂ O ₅ is preferably 0 to 2%. If the content of P ₂ O ₅ exceeds 2%, the glass is likely to undergo phase separation, and the stability decreases.

La ₂ O ₃ is a component that enables vitrification when the content of B ₂ O ₃ is large, enhances water resistance, and enhances the refractive index, and is an optional component in the present invention. The La ₂ O ₃ —B ₂ O ₃ —ZnO system has a higher refractive index than the SiO ₂ —B ₂ O ₃ —ZnO system, is closer to the refractive index of a general phosphor, and is an excellent glass for suppressing light scattering. Is. The content of La ₂ O ₃ is preferably 0 to 20%. If the content of La ₂ O ₃ exceeds 20%, the crystallization tendency becomes high and the stability of the glass decreases.

TeO ₂ is a component that lowers the sintering temperature, suppresses crystallization of glass, and stabilizes it, and is an optional component in the present invention. The content of TeO ₂ is preferably 0 to 10%. When the content of TeO ₂ is more than 10%, it is a component that is extremely volatilized, so that melting control may be difficult. The content of TeO ₂ is more preferably 7% or less.

In addition to the above, Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , ZrO ₂ , Gd ₂ O ₃ , and Ga ₂ O ₃ are components that enhance water resistance and suppress crystallization of glass. It is an optional component that may be contained in the glass of the present invention. However, since each is a component that raises the sintering temperature of glass, the content of each of these components is preferably 10% or less, and more preferably 5% or less.

Ce ₂ O ₃ , Sb ₂ O ₃ and SnO ₂ are components that adjust redox and are optional components that may be contained in the glass of the present invention. However, if a large amount is added, coloring may occur. Therefore, when it is added, a small amount of 1% or less is preferable, and 0.5% or less is more preferable.

_{Fe 2 O 3, CuO, Mo} 2 O 3, V 2 O 5, Cr 2 O 3 are the components to color the glass, not preferred for use in the mother glass. It is preferable that the glass of the present invention does not contain as much as possible, and even if it does, the content of each of them is preferably 0.5% or less. Further, the total amount of these components is preferably 0.5% or less.

  The glass having the above composition has a relatively low glass transition point Tg (hereinafter, also simply referred to as “Tg”), and it is particularly preferable that the Tg is 450 to 650 ° C. If the glass transition point is more than 600 ° C., the temperature during firing will be high during the manufacturing process of the present light conversion member, and depending on the type of phosphor used, the phosphor may be deactivated, or the glass and the phosphor may be separated from each other. There is a possibility that the quantum yield of the light conversion member may decrease due to reaction or the like. In order to suppress the decrease in quantum yield, the Tg of glass is preferably 650 ° C or lower, more preferably 600 ° C or lower, and further preferably 580 ° C or lower.

  On the other hand, when the glass transition point Tg is less than 450 ° C., it is necessary to lower the firing temperature, but the temperature is lower than the temperature at which the glass flows and below the thermal decomposition temperature of the resin or organic compound used for molding the light conversion member. The carbon content in the light conversion member is large, the light absorption is increased, and the quantum yield of the light conversion member may be reduced. Moreover, there is a possibility that the amount of included bubbles increases, the light transmittance of the light conversion member decreases, and the light emission efficiency of the light source decreases. The glass transition point Tg is more preferably 475 ° C. or higher, still more preferably 500 ° C. or higher. In the present specification, Tg of glass is calculated from a DTA curve.

Further, the density of the glass is preferably 2.5 to 5.0 g / cm ³ . If the ratio is out of this range, the difference in specific gravity from the phosphor described later becomes large, the phosphor particles are not uniformly dispersed in the glass powder, and there is a possibility that the conversion efficiency will be reduced when used as a light conversion member. The density is more preferably 2.7 to 4.5 g / cm ³ , and further preferably 3.0 to 4.3 g / cm ³ .

  Further, the refractive index of glass is preferably 1.5 or more at a wavelength of 633 nm. There is a possibility that the difference in refractive index from the phosphor particles becomes large, the light scattering becomes large when used as a light conversion member, and the conversion efficiency decreases. The refractive index is more preferably 1.55 or more, still more preferably 1.6 or more.

<Glass manufacturing method>
Next, the glass of the present invention may be obtained by mixing a glass raw material powder so as to have the above-mentioned desired composition, melting this, and then cooling and solidifying the glass according to a conventional method. As the glass raw material powder for producing the light conversion member described later, by the present production method, the glass obtained by once melting and then solidifying is pulverized by a conventional method to obtain a glass powder having a predetermined particle size. You can use it.

[Light conversion member]
As described above, the present light converting member is made of glass in which phosphor particles are dispersed, and the glass forming the present light converting member is made of the present glass. Such a light conversion member converts the wavelength of the light emitted from the light source, and makes it possible to irradiate the wavelength-converted light to the outside. As the light source used here, an LED light emitting element is preferable.

The type of the phosphor particles used in the light conversion member is not limited as long as it can convert the wavelength of the light source, and examples thereof include known phosphor particles used in the light conversion member. Examples of such phosphor particles include particles made of phosphors such as oxides, nitrides, oxynitrides, sulfides, oxysulfides, halides, aluminate chlorides or halophosphate chlorides. .. Among the above-mentioned phosphors, those that convert blue light into red, green or yellow are preferable, and those having an excitation band at a wavelength of 400 to 500 nm and an emission peak (λ _p ) at a wavelength of 500 to 700 nm are more preferable. preferable. Further, in order to extract light of a higher wavelength, those having an excitation pair at wavelengths over 410 to 500 nm and having an emission peak (λp) at wavelengths 500 to 700 nm are more preferable.

As described above, the present light converting member mainly irradiates the converted light to the outside without irradiating the light source light to the outside. When green emission is desired, phosphor particles having β type sialon activated with Eu ²⁺ (hereinafter, abbreviated as β-SiAlON in the present specification) as a base material and green to yellow emission are used Is a yttrium-aluminum composite oxide (Y ₃ Al ₅ O ₁₂ ; hereinafter abbreviated as YAG) activated with Ce ³⁺ , or a lutetium-aluminum composite oxide (Lu ₃ Al ₅ O ₁₂ ; Hereinafter, when it is desired to use the orange to red light emission of the phosphor particles having LAG as a base material in the present specification, a Ca solid solution α-sialon activated with Eu ²⁺ (hereinafter, in the present specification, Phosphor particles whose base material is a CASN-based crystal such as (α-SiAlON) or (Ca (Sr) AlSiN ₃ ).

These phosphors described above can withstand a high temperature during sintering with glass, and the temperature of members and phosphors near the phosphor rises during light emission, resulting in a decrease in brightness. Is.

  The phosphor may contain at least one compound selected from the group consisting of the above-mentioned compounds as long as the light passing through the light conversion member is converted into a desired color. The compounds of the species may be mixed and contained, or any one of them may be contained alone. From the viewpoint of ease of color design, it is preferable to contain any one of them alone.

The 50% particle diameter (hereinafter, abbreviated as 50% particle diameter in the present specification) D ₅₀ of the phosphor particles is preferably 1 to 30 μm. When the 50% particle diameter D ₅₀ of the phosphor particles is less than 1 μm, the specific surface area of the phosphor particles becomes large, and the phosphor particles may be easily deactivated. The 50% particle size D ₅₀ is more preferably 3 μm or more, further preferably 5 μm or more, and particularly preferably 7 μm or more. On the other hand, when the 50% particle diameter D ₅₀ of the phosphor particles exceeds 30 μm, the dispersibility in the light conversion member is deteriorated, the light conversion efficiency is deteriorated, and chromaticity unevenness may occur. Therefore, the 50% particle diameter D ₅₀ is more preferably 20 μm or less, further preferably 15 μm or less. In the present specification, the 50% particle size D ₅₀ is a value calculated from the particle size distribution obtained by laser diffraction particle size distribution measurement as a 50% value in cumulative% on a volume basis.

  The quantum yield of the light conversion member is preferably 80% or more. If the quantum yield is less than 80%, the light utilization efficiency is poor and a large amount of light is consumed without being used, which is not preferable. The quantum yield of the light conversion member is more preferably 85% or more, further preferably 90% or more. The quantum yield is represented by the ratio between the number of photons emitted from the sample as light emission and the number of photons absorbed by the sample when irradiated with excitation light. The number of photons is measured by the integrating sphere method.

  The light conversion member preferably has a plate shape with a thickness of 300 μm or less, for example, 50 to 300 μm. When the thickness of the light converting member is 50 μm or more, handling of the light converting member becomes easy, and cracking of the light converting member can be suppressed especially when the light converting member is cut into a desired size. The thickness of the light conversion member is more preferably 80 μm or more, further preferably 100 μm or more, and particularly preferably 120 μm or more. When the thickness of the light conversion member is 300 μm or less, the heat generation of the phosphor can be released and the temperature quenching can be suppressed by mounting the light conversion member on a substrate having higher thermal conductivity than glass. The mounting method is a method of sticking with an adhesive such as a silicone resin, a method of sintering the light conversion member and the high thermal conductivity substrate, or a method in which the flatness of the substrates is extremely increased and the melting point or softening point of the material or less is The method of joining at low temperature is mentioned. Here, the high thermal conductivity substrate may be a light emitting element or a bulk body having a thickness of 10 μm or more. The thickness of the light conversion member is preferably 270 μm or less, more preferably 250 μm or less. It is preferably 220 μm or less.

  The planar shape of the present light conversion member is not particularly limited. For example, when the light conversion member is used in contact with the light source, the shape of the light conversion member is manufactured according to the shape of the light source in order to prevent light from leaking from the light source. Since the light source is generally rectangular or circular, the light conversion member is also preferably rectangular or circular. Further, it is preferable that the light conversion member has a plate shape, that is, a rectangular cross section. The smaller the variation in the plate thickness within the light conversion member is, the smaller the variation in the in-plane color is, which is preferable.

  The light conversion member is basically made of glass in which phosphor particles are dispersed. The mixing ratio of the glass and the phosphor particles is not particularly limited, but the phosphor particles in the light conversion member are preferably more than 15% and 40% or less, and glass is 60% or more and less than 85% by volume.

  If the phosphor particles are contained in an amount of more than 15% and less than 85% of glass, it is possible to irradiate the converted light mainly without irradiating the light source light to the outside. The volume fraction of the phosphor particles is more preferably 20% or more, further preferably 25% or more. The volume fraction of glass is more preferably 80% or less, still more preferably 75% or less. The upper limit of the content of the phosphor particles is more preferably 37.5% or less, further preferably 35% or less.

  The present light conversion member may further have a predetermined heat-resistant filler dispersed in the glass. By containing the heat-resistant filler in this way, shrinkage during firing can be suppressed and the dispersed state of the phosphor can be made uniform. When the phosphors are uniformly dispersed in this way, it is possible to reduce the color variation of the converted light emitted from the light converting member to the outside, and it is possible to obtain light having a stable and desired tint.

  When the heat-resistant filler is used in the present light conversion member, it is sufficient that it has heat resistance to the firing temperature during the production of the light conversion member, and examples thereof include alumina, zirconia, and magnesia. You may contain 1 or more types.

  As described above, when the phosphor particles and the heat-resistant filler are dispersed in the glass, it is possible to sufficiently suppress the shrinkage of the light conversion member during firing. Therefore, glass, phosphor particles, and heat-resistant filler are contained in a predetermined ratio. For example, when the total amount of these is 100%, it is preferable to contain the heat-resistant filler in a volume fraction of 0.1 to 30%. If this content is less than 0.1%, it may not be possible to sufficiently suppress shrinkage, and if it exceeds 30%, the light transmissivity of the light of the light conversion member may decrease, and the light source utilization efficiency may decrease. is there.

  At this time, it is preferable to contain 50 to 85% of glass and 15 to 40% of phosphor particles in terms of volume fraction. By having such a content, as the light conversion member, the light transmittance of the light from the light source, the light conversion amount of the phosphor particles, can be manufactured in a well-balanced manner, and the shrinkage at the time of manufacture can be suppressed, It is possible to suppress uneven conversion chromaticity.

  When the heat-resistant filler is contained as described above, shrinkage during firing can be suppressed, variation in in-plane light conversion chromaticity can be suppressed, and light with little chromaticity unevenness can be obtained. Furthermore, since the light transmissivity of the light conversion member can be maintained high, the luminous conversion efficiency can be improved while maintaining the luminous flux amount.

[Method of manufacturing light converting member]
The light conversion member is preferably made of a sintered body of glass powder, phosphor particles, and, if necessary, a mixed powder of heat-resistant filler. Further, the present light conversion member is more preferably composed of a sintered body obtained by firing a slurry obtained by kneading the mixed powder, a resin and an organic solvent, and applying the slurry to a transparent resin and drying it. It is further preferable that the glass sheet is obtained by sintering the obtained green sheet. In the present specification, the mixture of the resin and the organic solvent may be referred to as a vehicle.

  As described above, in order to produce the present light conversion member as a sintered body, a kneading step of kneading glass powder, phosphor particles, resin and an organic solvent, and further a heat-resistant filler into a slurry to obtain a slurry is obtained. A forming step of forming the slurry into a desired shape and a forming step of forming the slurry into a light conversion member may be sequentially performed.

(Kneading process)
The kneading step in the present invention is to knead glass powder, phosphor particles, a resin and an organic solvent, and optionally a heat-resistant filler to form a slurry, as long as these raw materials can be uniformly kneaded. In this kneading, known kneading methods such as a dissolver, a homomixer, a kneader, a roll mill, a sand mill, an attritor, a ball mill, a vibrator mill, a high speed impeller mill, an ultrasonic homogenizer, and a shaker may be used. Good. When the light conversion member contains a heat resistant filler, a heat resistant filler as a raw material component may be simultaneously mixed in the kneading step to obtain a slurry.

  The glass powder used here may be prepared by mixing plural kinds of known glass powders so as to satisfy the above-mentioned glass composition, or may be prepared by mixing the components so as to have predetermined thermal characteristics. Alternatively, the glass may be melted in an electric furnace or the like and rapidly cooled to produce glass having a predetermined composition, which may be crushed and classified to prepare.

At this time, the 50% particle diameter D ₅₀ of the glass powder is preferably less than 3.5 μm. When the 50% particle diameter D ₅₀ is 3.5 μm or more, the phosphor particles and the heat-resistant filler are not evenly dispersed in the glass powder, and the light conversion efficiency decreases when used as a light conversion member, or the shrinkage amount during firing. May become large. The 50% particle size D ₅₀ is more preferably 2.5 μm or less, and further preferably 1.9 μm or less.

Further, the maximum particle diameter D _max of the glass powder is preferably 30 μm or less. If the maximum particle size D _max exceeds 30 μm, it becomes difficult to uniformly disperse the phosphor particles and the heat-resistant filler in the glass powder, and when the light conversion member is manufactured, the light conversion efficiency of the phosphor decreases, The contraction amount may increase. D _max is more preferably 20 μm or less, still more preferably 15 μm or less. In the present specification, D _max is the value of the maximum particle size calculated by laser diffraction type particle size distribution measurement.

  The phosphor particles and the heat-resistant filler are the particles described in the light conversion member.

  As the resin, ethyl cellulose, nitrocellulose, acrylic resin, vinyl acetate, butyral resin, melamine resin, alkyd resin, rosin resin, etc. can be used. As the organic solvent, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols, ethers, ketones, esters and the like can be used. In order to improve the strength of the green sheet, the vehicle preferably contains butyral resin, melamine resin, alkyd resin, rosin resin and the like.

  When the above components are kneaded, the phosphor particles and the glass powder may be mixed so that the mixing ratio of the phosphor and the glass in the light conversion member falls within the range described above. Specifically, when the total amount of the phosphor particles and the glass powder is 100%, the content of each component in the mixed powder is a volume fraction of the phosphor particles of more than 15% and 40% or less, and the glass powder. Is preferably 60% or more and less than 85%.

  When the heat-resistant filler is mixed, when the total amount of the phosphor particles, the heat-resistant filler and the glass powder is 100%, the content of each component in the mixed powder is a volume fraction, and the phosphor particles are It is preferable that the content is more than 15% and 40% or less, the heat-resistant filler is 0.1% or more and 30% or less, and the glass powder is 50% or more and less than 85%.

  If the phosphor particles are contained in an amount of more than 15% and the glass powder is less than 85%, the converted light can be mainly irradiated to the outside while the light of the light source is hardly irradiated to the outside.

  If the volume fraction of the phosphor particles exceeds 40% and the volume fraction of the glass powder is less than 60%, the sinterability of the mixture of the phosphor particles and the glass powder is impaired and the voids inside the sintered body increase. Moreover, the light transmittance of the light conversion member may be lowered. Further, the amount of fluorescent color light to be converted is increased, and there is a possibility that light of a desired color may not be obtained.

  Further, when the volume fraction of the heat-resistant filler is 0.1% or more, shrinkage during firing of the light conversion member can be efficiently suppressed, and the state in which the phosphor particles are uniformly dispersed is preferably maintained. Further, if the volume fraction of the heat-resistant filler exceeds 30%, the sinterability of the mixed powder may be impaired, the voids inside the sintered body may increase, and the light transmittance of the light conversion member may decrease.

  The vehicle composed of the resin and the organic solvent may be mixed with the mixed powder in an amount such that the mixture has a viscosity such that it can be molded into a predetermined shape in the next molding step to form a slurry.

(Molding process)
The forming step in the present invention is to form the slurry obtained in the kneading step into a desired shape. The forming method is not particularly limited as long as it can give a desired shape, and examples thereof include known methods such as a press forming method, a roll forming method, and a doctor blade forming method. A green sheet obtained by the doctor blade molding method is preferable because a light conversion member having a uniform film thickness can be efficiently manufactured in a large area.

  The green sheet can be manufactured, for example, by the following steps. Glass powder, phosphor particles and heat resistant filler are kneaded in a vehicle and defoamed to obtain a slurry. The obtained slurry is applied onto a resin film by a doctor blade method and dried. After drying, it is cut into a desired size and the resin film is peeled off to obtain a green sheet (kneaded product). Further, by pressing these into a laminated body, a molded body having a desired thickness can be secured.

  Here, the resin film on which the slurry is applied is not particularly limited as long as it has releasability. It is preferable to use a resin film having a uniform thickness so that a green sheet having a uniform thickness can be obtained. Examples of such a resin film include a PET film and the like. ..

(Firing process)
The firing step of the present invention is a step in which the shaped slurry obtained in the shaping step is fired to be sintered to obtain a light conversion member. The firing in the firing step is to sinter the mixed powder to obtain glass containing the phosphor particles and the heat-resistant filler dispersed therein, and the sintered glass body may be manufactured by a known firing method.

The firing step is not particularly limited as long as it can be fired into a sintered glass body. In order to reduce the inclusion bubbles, the firing atmosphere is preferably a reduced pressure atmosphere of 10 ³ Pa or less or an atmosphere having an oxygen concentration of 1 to 25%. In addition, the maximum firing temperature in this step is set to 700 ° C. or lower, and the maximum temperature is preferably in the range of 500 to 700 ° C. The firing time is preferably in the range of 0.5 to 10 hours. In the method for producing a light conversion member of the present invention, if it is performed outside the above range, the quantum yield of the light conversion member may decrease.

  By polishing the obtained light conversion member, the surface flatness can be enhanced and the adhesion to the substrate can be enhanced. As for the surface flatness of the light conversion member when polished, Ra is 0.3 μm or less, preferably 0.2 μm or less, and more preferably 0.1 μm or less in terms of JIS-B0601 surface roughness defined in JIS 2001. Further, in order to improve the efficiency of productivity, it may be possible to polish only the side of adhesion to the base material.

[Illumination light source]
The illumination light source of the present invention comprises the present light conversion member and a light source capable of irradiating light to the outside through the light conversion member.

  By combining the light conversion member and the light source obtained as described above, it can be used as an illumination light source that emits a desired color. It is preferable that the light conversion member is arranged in contact with the light source because light leakage can be prevented. As the light source, an LED light emitting element is preferable, and a blue LED light emitting element is more preferable. If the LED light emitting element is used as a light source, it can be used as an LED illumination light source.

  An example of such an illumination light source is the illumination light source shown in FIG. The illumination light source 10 includes a substrate 11 having a concave portion, an LED 12 arranged in the center of the concave portion, and a light conversion member 13 arranged so as to cover the concave portion of the substrate 11. At this time, the substrate is not particularly limited as long as it is a conventionally known material used as an illumination light source, such as glass ceramics. This substrate 11 has a recess for arranging and fixing the LED in order to package the LED.

  The LED 12 is arranged and fixed in the center of the recess, and the light conversion member 13 is bonded to the substrate 11 so as to cover the inside of the recess to seal the LED 12. Therefore, the light emitted from the LED 12 is directed to the opening side of the substrate 11 directly or after being reflected by the substrate 11, and passes through the light conversion member 13. At this time, the light passing through the light converting member 13 has its wavelength converted into converted light by the phosphor particles inside the light converting member 13, and the obtained converted light is irradiated to the outside.

Further, another embodiment of the illumination light source of the present invention includes the illumination light source shown in FIG. The same numbers as in FIG. 1 are given to the same members as in FIG. The illumination light source 10 shown in FIG. 2 includes a substrate 11 having a recess, an LED 12 disposed in the center of the recess, and a light conversion member 13 disposed on the upper surface of the LED 12. This embodiment differs from the illumination light source shown in FIG. 1 in that the light conversion member 13 is provided on the LED 12 in a laminated manner, and at this time, the LED 12 and the light conversion member 13 are fixed by an adhesive. As the adhesive used here, one having high light transmittance after solidification is used. As the substrate and the LED, the same materials as those described for the illumination light source shown in FIG. 1 can be used.

Still another embodiment of the illumination light source of the present invention includes the illumination light source shown in FIG. FIG. 3 is an example of using the reflected light obtained by reflecting the light emitted from the LED by the light conversion member. The same numbers as in FIG. 1 are given to the same members as in FIG. The illumination light source 20 shown in FIG. 3 is provided with a substrate 11 having a concave portion, an LED 12 arranged at the center of the concave portion, and a position largely separated from the LED 12 at an angle such that light emitted from the LED 12 is obliquely incident. The light conversion member 13 and the lens 21 arranged between the LED light source 12 and the light conversion member 13. The substrate 11, the light conversion member 13, and the lens 21 may be held and fixed by an arbitrary member so that a predetermined structure can be maintained.
In FIG. 3, the light L emitted from the LED 12 is condensed through the lens 21, and the light reaching the light conversion member 13 is converted in wavelength by the phosphor particles inside the light conversion member 13 to be converted light, and a part of the light is converted. The light is transmitted through the light converting member 13 and is partially reflected to be reflected light L ′.

Further, as another embodiment of the illumination light source of the present invention, the illumination light source shown in FIG. 4 can be cited. FIG. 4 shows an example in which a laser is used as a light source and the reflected light reflected by the light conversion member is used. The illumination light source 30 shown in FIG. 4 includes a laser diode 31 and a light conversion member 13 arranged at a position apart from the laser diode 31 at an angle such that the light of the laser diode 31 is obliquely incident. ing. The laser diode 31 and the light conversion member 13 may be fixed by an arbitrary member so that a predetermined structure can be maintained.

  Hereinafter, the present invention will be described in more detail based on Examples, Comparative Examples and Reference Examples, but the present invention should not be construed as being limited to these Examples. In addition, Example 1 described below is a reference example showing the production, characteristics, and the like of the glass prepared for producing the light conversion member (Examples 1-1 to 1-26 are Example Reference Examples, and Example 1-27). 1 to 37 are comparative reference examples), and these are collectively shown in Tables 1 and 2. Here, the reference example of the present invention shows the glass which is within the range of the glass composition of the present light converting member, and the comparative reference example shows the glass which is not within the range of the glass composition of the present light converting member. In addition, "-" of Tables 1-2 shows that it is not evaluated.

In addition, Example 2 described below is an Example (Example 2-1 to Example 2-8, Example 2-12 to 18) and a Comparative Example (Example 2-9 to Example 2-11, Example 2-19 to Example). 2-21) is shown.

[Example 1: Glass production]
Raw materials for the respective components were prepared so as to have the compositions shown in Tables 1 and 2 in terms of mol% based on oxides, and the glass raw materials were mixed to obtain a glass composition. Example 1-1 to Example 1-18, Example 1-27 at 1550 ° C. in a platinum crucible, Example 1-19 to Example 1-26, Example 1-28 to Example 1-37 are platinum crucible at 1400 ° C. Each was heated and melted in an electric furnace at 0 ° C., and a part of the melt was rapidly cooled by a rotating roll to form a glass ribbon. A part of the melt was cooled after molding to obtain a glass plate. Note that Bi ₂ O ₃ and PbO were not contained in the compositions shown in Examples 1-1 to 1-37.

The obtained glass ribbon was crushed with a ball mill and passed through a # 100 mesh sieve to obtain a powder (glass powder) having a 50% particle diameter D ₅₀ of 3 μm in each of Examples 1-1 to 1-37. Got

The glass transition point Tg of the glass of each example was measured using a differential thermal analyzer (Rigaku Corporation, trade name: TG8110). Further, the 50% particle diameter D ₅₀ of the glass powder was calculated by a laser diffraction particle size distribution measurement (manufactured by Shimadzu Corporation, device name: SALD2300).
The coefficient of thermal expansion (CTE) of glass was determined as an average coefficient of linear thermal expansion (× 10 ⁻⁷ ) at 50 to 350 ° C. by a thermomechanical analyzer (TMA).
The specific gravity d was measured by the Archimedes method using the glass plate obtained in each example.
The thermal expansion coefficient and the specific gravity in Examples 1-15 to 1-18 are values calculated by calculation from the composition of glass.

  The sinterability was evaluated as follows. First, about 3 g of the glass powder obtained in each example was molded into a green compact, which was heated to the firing temperature shown in Tables 1 and 2 at a rate of 10 ° C / min. Next, after holding at the firing temperature for 30 minutes, the electric furnace was turned off and allowed to cool to obtain a fired body. The obtained fired body was evaluated as “◯” when the fired body was fluidized after firing and the corners were rounded to give a glassy luster.

  The water resistance was tested by exposing it to an environment of 85 ° C / 85% for a predetermined time using a high temperature and high humidity tank TH401HE (trade name) manufactured by ETAC. As the sample, a glass plate obtained in each example was processed into a plate shape having a thickness of 1 mm and a size of 20 mm × 20 mm, and both surfaces thereof were mirror-polished.

  After 6 hours, 24 hours, and 168 hours (1 week), the sample was taken out and confirmed, and it was judged whether 5 or more white spots of 1 mm or more were deposited. The glass that had been deposited after 6 hours was confirmed by "x", the glass that was deposited after 24 hours was confirmed by "△", and the glass that was deposited after 168 hours was confirmed by "○". The glass in which precipitation was not confirmed even after 168 hours was evaluated as “⊚”.

  For reference, soda lime glass (SLS) was also evaluated by performing the same test, and was “◯”.

[Example 2: Production of light conversion member]
(1) Next, using the glass powder obtained in Example 1, a dry airflow classifier was used to further adjust the particle size distribution to a narrow distribution, and the 50% particle size D ₅₀ was 1.4. ˜1.6 μm, maximum particle size D _max was 21 μm or less, and a light conversion member was manufactured as follows. As the phosphor particles to be dispersed in the glass, an α-SiAlON: Eu ²⁺ phosphor having a 50% particle diameter D ₅₀ of 16 μm and a phosphor peak wavelength of about 590 nm under 450 nm excitation was used. The frit (glass powder) used here corresponds to each number in Example 1 such that the glass obtained in Example 1-1 is glass 1, the glass obtained in Example 1-2 is glass 2, and so on. As described above, the glass number was given up to glass 37.

  Glass powder and phosphor particles were mixed in a combination of glass and phosphor as shown in Table 3 so that the volume fraction was 80:20. Further, it was kneaded with a vehicle and defoamed to obtain a slurry. This slurry was applied to a PET film (manufactured by Teijin Ltd.) by the doctor blade method. This was dried in a drying furnace for about 30 minutes, cut into a size of about 7 cm square, and the PET film was peeled off to obtain a green sheet having a thickness of 0.3 to 0.5 mm.

  This was placed on a mullite substrate coated with a release agent, and the firing atmosphere was set to the firing temperature as shown in Table 3, and the firing atmosphere was set to atmospheric firing, to manufacture the light conversion members of Examples 2-1 to 2-8. The thickness of the obtained light conversion member was about 0.2 mm. The firing conditions were such that the temperature was raised to the firing temperature shown in Table 3 at a rate of 10 ° C./min, and the firing temperature was maintained for 30 minutes, after which the heater of the electric furnace was cut off and allowed to cool.

  With respect to the obtained light conversion members of Examples 2-1 to 2-8, a test package was prepared, and respective characteristics of quantum yield and brightness decrease were measured and evaluated. The test package is a 1 mm □ × 200 μm thick light through a LED (made by Cree, product name: EZ1000) with a silicone adhesive (made by Shin-Etsu Chemical Co., Ltd.) in the center of the concave of a glass ceramic substrate having a concave. The conversion member laminated and adhered was obtained by disposing it.

  The quantum yield of the light conversion member was obtained by cutting out the central portion of the obtained light conversion member to a size of 1 cm square and using an absolute PL quantum yield measuring device (Hamamatsu Photonics Co., Ltd., trade name: Quantauru-QY). The excitation light wavelength was measured at 450 nm.

  The glass of Examples 1-1, 1-6, and 1-7 was processed into a plate having a thickness of 1 mm and a size of 20 mm × 20 mm, and both surfaces thereof were mirror-polished, and the light transmittance was used by Perkin Elmer. When measured by UV-Vis Spectrometer Lambda 950 manufactured by K.K., the transmittances at 450 nm were 86.9%, 86.9% and 86.5%, respectively.

  The brightness reduction amount measurement test of the light conversion member was calculated by applying a current of 750 mA to the LED, performing a test for 200 hours under a test environment of 100 ° C., and measuring the change (decrease) in the total luminous flux amount before and after the test. .. At this time, the total luminous flux was measured using an integrating sphere manufactured by Labsphere.

  (2) As a comparative example, a glass having the composition shown in Table 4 was produced by the same operation as in Example 1, and using this, a light conversion member was obtained by the same operation as in Example 2. The sinterability and water resistance of the glass compositions shown in Table 4 were ◯. Regarding the obtained light conversion member, the quantum yield and the decrease in brightness were examined by the same operation as in Example 2 above, but the quantum yield was good, but the decrease in brightness was remarkable and the member had a short life. I understood it. When the sample after the test was subjected to STEM analysis, a metal colloid of bismuth was confirmed at the interface between the phosphor particles and the glass. This is because the vibrational energy corresponding to the Stokes shift, which remains in the photoexcited phosphor, accumulates in the vicinity of the phosphor to generate heat, and finally the light conversion member is constituted by the action caused by the light of the blue LED. It is considered that the glass was reduced and colloid was formed. It is considered that the coloring caused the brightness to decrease.

  (3) Furthermore, the phosphor content, the thickness, and the firing temperature of the glass 1 and the glass 19 are as shown in Table 5, and the light conversion member was obtained by the same operation as in Example 2. The LED light absorptance of the obtained light conversion member was calculated and summarized in Table 5.

As for the LED light absorption rate, an LED (manufactured by Cree, product name: EZ1000) is arranged in the center of a concave portion of a glass ceramic substrate having a concave portion, and a light conversion member having a substrate size of 5 to 7 mm is arranged so as to cover the LED. Using the arranged ones, it was calculated by the following formula.

LED light absorption rate = [LED light intensity-blue missing intensity of light conversion member] / LED light intensity

(In the formula, [LED light intensity] and [blue light-extracting intensity of light conversion member] are all numerical values obtained by integrating light intensities of 410 nm to 490 nm.)

  As is clear from Tables 3 to 5, the light conversion member of the present invention is composed of glass powder having a specific glass composition and phosphor particles, and is sufficiently baked even if the phosphor particles are contained in an amount of more than 15% by volume. In addition, it is possible to suppress the decrease in luminance to a low level of 3% or less when used for a long time. In addition, the light conversion member of the present invention has a good quantum yield of 85% or more, and by containing a large amount of phosphor particles, the absorptivity of LED light as a light source is 98% or more, which is very excellent. It turned out to be a thing.

In Examples 2-9 to 2-11, a glass containing a large amount of Bi ₂ O ₃ was used, and after the photothermal resistance test, a metal colloid was formed in the glass near the interface between the phosphor and the glass. And the decrease in brightness was large.

The photoexcited phosphor undergoes radiative transition from the electronically excited state to the ground state with vibration relaxation, but at that time, vibrational energy corresponding to the Stokes shift remains near the phosphor and generates heat. At this time, the glass containing Bi ₂ O ₃ slightly absorbs the light of 450 nm and generates heat in the vicinity of the phosphor in the first place, but due to the above reason, the temperature becomes higher and the glass is reduced by the action caused by the light. It is considered that the colloidal coloring caused the brightness to decrease. This is considered to be the same also in the glass containing PbO.

  On the other hand, with the glass composition of the present invention, the problem of colloid formation as described above is unlikely to occur, there is almost no decrease in brightness, and an excellent light conversion member is obtained.

  INDUSTRIAL APPLICABILITY The light conversion member of the present invention has good sinterability, water resistance, and suppression of deterioration in luminance, has a large LED light absorption rate, and can convert a light source into light of a desired color.

10, 20, 30 ... Illumination light source, 11 ... Substrate, 12 ... LED, 13 ... Light conversion member, 21 ... Lens, 31 ... Laser diode

Claims (14)

A light conversion member made of glass in which phosphor particles are dispersed,
The glass, in mol% based on _{oxides, SiO 2 0~40%, B 2} O 3 10~45%, Al 2 O 3 0~10%, ZnO 25~64%, alkaline earth metal oxides (MgO + CaO + SrO + BaO) 0 to 15 %, alkali metal oxide (Li ₂ O + Na ₂ O + K ₂ O) 0 to 5%, Bi ₂ O ₃ 0.5% or less, PbO 0.5% or less, and The light conversion member, wherein the phosphor particles are contained in the glass in an amount of more than 15% by volume.   The light conversion member according to claim 1, wherein the alkali metal oxide is 0.5% or less.   The light conversion member according to claim 1, wherein the ZnO is 40% or more. The light conversion member according to claim 1, wherein the B ₂ O ₃ content is 35% or less.   The phosphor particles have one or more compounds selected from the group consisting of oxides, nitrides, and oxynitrides having an excitation band at a wavelength of 400 to 500 nm and an emission peak at a wavelength of 500 to 700 nm. The light conversion member according to any one of claims 1 to 4.   The light conversion member according to claim 5, wherein the phosphor particles are made of an oxynitride phosphor. The light conversion member according to claim 6, wherein the oxynitride phosphor includes at least one of α-SiAlON: Eu ²⁺ and β-SiAlON: Eu ²⁺ .   The light conversion member according to claim 1, wherein a heat resistant filler is dispersed in the glass.   The light conversion member according to claim 1, which has a plate shape with a thickness of 300 μm or less.   The light conversion member according to any one of claims 1 to 9, wherein the glass has a light transmittance of 80% or more at a wavelength of 450 nm in a thickness of 1 mm of the glass.   An illumination light source, comprising: the light conversion member according to any one of claims 1 to 10; and a light source capable of irradiating light to the outside through the light conversion member.   The illumination light source according to claim 11, wherein the light source is an LED light emitting element. A kneading step of kneading glass powder, phosphor particles, a resin and an organic solvent to form a slurry, a forming step of forming the obtained slurry into a desired shape, and a step of firing the formed slurry to form a light conversion member. A method for manufacturing a light conversion member, which comprises a firing step,
The said light conversion member manufactured is the light conversion member of any one of Claims 1-10, The manufacturing method of the light conversion member characterized by the above-mentioned.   The method for producing a light conversion member according to claim 13, wherein in the kneading step, a heat-resistant filler is also added to knead to form a slurry.

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