JP2018043912A - Photoconversion member, illumination light source and method for producing photoconversion member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoconversion member that: allows sufficient sintering even when containing a large number of phosphor particles; can significantly inhibit a decrease in the brightness of conversion light; and has excellent water resistance.SOLUTION: A photoconversion member is composed of glass with phosphor particles dispersed. The glass has a composition comprising, on an oxide basis by mol%, SiO0-40%, BO10-45%, AlO0-10%, ZnO 25-64%, alkaline earth metal oxides (MgO+CaO+SrO+BaO) 0-30%, alkali metal oxides (LiO+NaO+KO) 0-5%, BiO0.5% or less, and PbO 0.5% or less. In the glass, the content of the phosphor particles is more than 15 vol.%.SELECTED DRAWING: None

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 an illumination light source with a minute electric power and is expected to be applied to illumination applications. At this time, it is sufficient that the LED can be used by irradiating its emission color as it is, but since there are a wide variety of emission colors required, it is common to use phosphor particles that convert the wavelength of the LED light.

  For example, white light of a white LED is obtained by combining blue light emitted from a blue LED element serving as a light source and red light or the like obtained by converting a part of the blue light with 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 has insufficient heat resistance and light resistance.

  As a light conversion member that obtains a white illumination light source that has a longer life than using resin, glass powder is used instead of resin, and phosphor powder is dispersed in glass by mixing and sintering with phosphor powder. Those are known (for example, see 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 light into a light emission color by a phosphor. By converting almost all of the LED light in this way, it is possible to extract light having a relatively wide wavelength width due to light emission of an arbitrary phosphor and having high luminance and suppressed color mixing of the LED light.

  However, the light emitting color conversion member disclosed in Patent Document 1 is 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.

  Although it is conceivable to increase the content of the phosphor powder in order to suppress the color mixing of the LED light with reference to the above-mentioned Patent Document 1, sintering is sufficient when the phosphor particles are contained in a large amount in the glass. It has been found that even if the sintering is sufficient, there is a case where the brightness is significantly lowered when the use is continued, or an LED illumination light source having an excellent quality may not be obtained.

  Therefore, in view of the above problems, the present invention can sufficiently perform the sintering even when the phosphor particles are contained in a large amount, and can significantly suppress the decrease in the luminance of the converted light over a long period of 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 intensive studies by the present inventors, by using a glass having a predetermined composition, it is possible to sufficiently sinter even when the content of the phosphor particles is large, and the luminance of the converted light is reduced in use over a long period of time. It has been found that it has water resistance that is difficult to change even in humid environments, and has completed the present invention.

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 expressed in terms of mol% on an oxide basis, 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 to 30%, alkali metal oxide (Li ₂ O + Na ₂ O + K ₂ O) 0 5%, Bi ₂ O ₃ 0.5% or less, and 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 includes a kneading step of kneading glass powder, phosphor particles, a resin and an organic solvent into a slurry, a molding step of molding the obtained slurry into a desired shape, and molding. A method for producing a light conversion member comprising firing the slurry to form a light conversion member, wherein the light conversion member produced is the light conversion member of the present invention. .

  And the illumination light source of this invention has the light conversion member of this invention, and the light source which can irradiate light outside through the said light conversion member, It is characterized by the above-mentioned.

  As described above, the light conversion member of the present invention and the method for producing the light conversion member can be sufficiently baked into a light conversion member even when the content of the phosphor particles is large, and stable converted light can be obtained even over a long period of use. The light conversion member can be irradiated.

  Since the illumination light source of the present invention uses the light conversion member of the present invention, the light converted by the phosphor can be stably obtained as described above. This is useful when light mainly composed of converted light is used as external irradiation light, and irradiation light composed of light having a desired wavelength can be obtained by selecting the type of 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 “main 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 desired glass containing phosphor particles dispersed therein.

  Here, the glass forming the present light conversion member is formed to have a glass composition described below. Such a light conversion member converts the wavelength of light (light source light) emitted from a light source, and makes it possible to irradiate the converted light obtained by this conversion to the outside. As the light source light, an LED that emits light in the vicinity of 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 radiated to the outside as a combined light of the light source light and the converted light. May be irradiated outside. In particular, the light source light emitted from near-ultraviolet LEDs and blue LEDs has a short wavelength and degrades resin-like sealing members. In order to achieve a design that suppresses variations in degree, it is preferable to mainly radiate converted light to the outside. In addition, when using an LED for a direction indicator lamp of a vehicle such as an automobile, from the viewpoint of safety standards and visibility, the light source light emitted from the blue LED is not radiated to the outside, and light with a large amount of converted light components and high color purity is used. It is preferable to irradiate the outside.

  Here, “mainly irradiating converted light to the outside” means that the transmitted light of the light source light out of the light irradiated to the outside from the light converting member is 3% or less of the light source light, Furthermore, it is preferably 2% or less, more preferably 1.5% or less, and still more preferably 1% or less.

<Glass>
The glass of the present invention is expressed in terms of mol% on the basis of oxide, 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 to 30%, 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 It is characterized by. Hereinafter, each component of this glass is demonstrated.

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

B ₂ O ₃ is a glass network former, can stabilize the glass, and is an essential component. The content of B ₂ O ₃ is 10 to 45%. If the content of B ₂ O ₃ is less than 10%, the glass becomes unstable, tends to be crystallized, and the sinterability may be impaired. On the other hand, if the content of B ₂ O ₃ exceeds 45%, the water resistance of the glass may be lowered. 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 the glass and suppresses crystallization, but is not an essential component in the present invention. Moreover, it is also a component which suppresses reaction with a fluorescent substance at the time of baking. 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, which may impair the sinterability. The content of Al ₂ O _3, preferably 0 to 8%, more preferably 0 to 6%.

  ZnO has the advantage of expanding the vitrification range and increasing the degree of freedom of glass composition, and is an essential component. ZnO is also a component that lowers Tg and lowers the sintering temperature. The content of ZnO is 25 to 64%. If the content of ZnO is less than 25%, the sinterability deteriorates 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 is likely to be crystallized, which may impair sinterability. The content of ZnO is preferably 40 to 64%, more preferably 45 to 60%.

  CaO, SrO, MgO and BaO alkaline earth metal oxides are components that lower the crystallization tendency and increase the stability of the glass and improve the sinterability, but the water resistance tends to decrease slightly. It is not an essential ingredient. The content 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%, 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 the total amount exceeds 30%, the stability of the glass is lowered, and the absorption edge of the glass is shifted to the longer 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%, and further preferably 0 to 1%.

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 to 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 decreases, the chemical durability of the glass decreases, the reaction with the phosphor accelerates during firing, the glass absorption edge shifts to the long wavelength side, and the LED element May absorb blue light. This total amount is more preferably 0 to 3%, still more preferably 0 to 0.5%. Since alkali metal oxides tend to lower the water resistance, it is preferable not to contain them unless there is a reason for particularly reducing Tg.

Bi ₂ O ₃ and PbO are components that are easily colloided by the action caused by light and heat, and are preferably not substantially contained. In the present invention, since a large amount of phosphor particles is contained, it is not preferable that these components are contained, because it tends to colloid at the interface between the phosphor particles and the glass and may cause a decrease in luminance of the light conversion member. Here, “substantially does not contain” means that the content is 0.5% or less.

  This glass consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. 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 oxide.

P ₂ O ₅ is a glass network former, and in the case of a small amount, P ₂ O ₅ is a component that improves water resistance, 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 tends to phase-separate and the stability decreases.

La ₂ O ₃ is a component that can be vitrified when the content of B ₂ O ₃ is large, increases water resistance and increases 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 excellent in suppressing light scattering. It is. The content of La ₂ O ₃ is preferably 0 to 20%. When the content of La ₂ O ₃ exceeds 20%, the tendency to crystallize increases and the stability of the glass decreases.

TeO ₂ is a component that lowers the sintering temperature and suppresses crystallization of the glass to stabilize 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 very volatile, and thus it may be difficult to control melting. 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 increase 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 both are components that increase the sintering temperature of the glass, the content of these components is preferably 10% or less, 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, since there is a possibility of coloring when the amount is large, 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 , and Cr ₂ O ₃ are components that color the glass, and thus are not preferable 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 is contained, the content thereof is preferably 0.5% or less. Furthermore, 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. In a glass having a glass transition point of over 600 ° C., the temperature during firing during the production process of the present light conversion member is high, and depending on the type of phosphor used, the phosphor may be deactivated, or the glass and phosphor There is a risk that the quantum yield of the light conversion member is lowered due to reaction. In order to suppress a decrease in quantum yield, the Tg of the glass is preferably 650 ° C. or lower, more preferably 600 ° C. or lower, and further preferably 580 ° C. or lower.

  On the other hand, if 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 thermal decomposition temperature of the resin or organic compound used when molding the light conversion member than the temperature at which the glass flows. In addition, the carbon content in the light conversion member is large, light absorption increases, and the quantum yield of the light conversion member may be reduced. Further, the encapsulated foam increases, the light transmittance of the light conversion member is lowered, and the light emission efficiency of the light source may be lowered. The glass transition point Tg is more preferably 475 ° C. or higher, and further preferably 500 ° C. or higher. In this specification, Tg of glass is calculated from a DTA curve.

Moreover, it is preferable that the density of glass is 2.5-5.0 g / cm < ³ >. Outside this range, the specific gravity difference with the phosphor described later increases, and the phosphor particles are not uniformly dispersed in the glass powder, and conversion efficiency may be reduced when the light conversion member is used. The density is more preferably 2.7 to 4.5 g / cm ³ , still more preferably 3.0 to 4.3 g / cm ³ .

  Further, the refractive index of the glass is preferably 1.5 or more at a wavelength of 633 nm. When the refractive index difference with the phosphor particles is increased and the light conversion member is used, light scattering increases, and conversion efficiency may be reduced. The refractive index is more preferably 1.55 or more, and still more preferably 1.6 or more.

<Glass manufacturing method>
Next, the glass of the present invention may be obtained by mixing glass raw material powder so as to have the above desired composition, melting it, and cooling and solidifying it according to a conventional method. As a glass raw material powder for producing a light conversion member to be described later, a glass powder obtained as a predetermined particle size by pulverizing a glass obtained by melting and solidifying by a conventional method by this production method. Use it.

[Light conversion member]
As described above, the present light conversion member is made of glass in which phosphor particles are dispersed. Here, the glass forming the present light conversion member is formed of the present glass. Such a light conversion member converts the wavelength of the light emitted from the light source, and enables the light having the converted wavelength to be radiated to the outside. As the light source used here, an LED light emitting element is preferable.

If the fluorescent substance particle used for this light conversion member can convert the wavelength of a light source, the kind will not be limited, For example, the well-known fluorescent substance particle used for a light conversion member is mentioned. Examples of such phosphor particles include particles made of a phosphor such as oxide, nitride, oxynitride, sulfide, oxysulfide, halide, aluminate chloride, or halophosphate. . Among the phosphors described above, those that convert blue light into red, green, or yellow are preferable, and those that have an excitation band at a wavelength of 400 to 500 nm and have an emission peak (λ _p ) at a wavelength of 500 to 700 nm are more preferable. preferable. Further, in order to extract light having a higher wavelength, it is more preferable to have an excitation pair at a wavelength exceeding 410 to 500 nm and an emission peak (λp) at a wavelength of 500 to 700 nm.

As described above, the present light conversion member mainly irradiates the converted light to the outside without substantially irradiating the light source light to the outside. If you want to use green luminescence, if you want to use phosphor particles based on Eu 2 ⁺ -activated β-sialon (hereinafter abbreviated as β-SiAlON in this specification), green to yellow luminescence Is a composite oxide of yttrium and aluminum activated with Ce ³⁺ (Y ₃ Al ₅ O ₁₂ ; hereinafter abbreviated as YAG), or a composite oxide of lutetium and aluminum (Lu ₃ Al ₅ O ₁₂ ; hereinafter, the phosphor particles as a base material the abbreviated LAG) herein, if you want to use the emission of orange to red, Ca dissolved α-sialon (hereinafter which is activated by Eu ^2+, herein Phosphor particles using a CASN crystal such as (Ca (Sr) AlSiN ₃ ) as a base material are used.

These phosphors described above can withstand high temperatures during sintering with glass, and phosphor materials that do not easily exhibit a temperature quenching phenomenon in which the temperature in the vicinity of the member or the phosphor increases during light emission and the luminance decreases. It is.

  The phosphor need only contain one or more compounds selected from the group consisting of the above-described compounds as long as the light passing through the light conversion member is converted into a desired color. One kind of compound 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.

The 50% particle diameter (hereinafter abbreviated as 50% particle size in the present specification) D ₅₀ of the phosphor particles is preferably 1 to 30 μm. If the 50% particle size D ₅₀ of the phosphor particles is less than 1 μm, the specific surface area of the phosphor particles is increased, 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 is more than 30 μm, the dispersibility is deteriorated in the light conversion member, the light conversion efficiency is deteriorated, and chromaticity unevenness may occur. Therefore, the 50% particle diameter _{D 50,} and more preferably 20μm or less, more preferably 15μm or less. In the present specification, the 50% particle size D ₅₀ is a value calculated as a 50% value in the integrated% on a volume basis from the particle size distribution obtained by laser diffraction particle size distribution measurement.

  The quantum yield of the present light conversion member is preferably 80% or more. If the quantum yield is less than 80%, the light use efficiency is poor, and a large amount of light is consumed without being used. The quantum yield of the light conversion member is more preferably 85% or more, and still more preferably 90% or more. The quantum yield is expressed as a ratio of the number of photons emitted from the sample as light emission when irradiated with excitation light and the number of photons absorbed by the sample. The number of photons is measured by the integrating sphere method.

  The light conversion member is preferably plate-shaped with a thickness of 300 μm or less, for example, 50 to 300 μm. When the thickness of the light conversion member is 50 μm or more, handling of the light conversion member is facilitated, and cracking of the light conversion member can be suppressed particularly when cutting to 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, heat generation of the phosphor can be released and temperature quenching can be suppressed by mounting on the substrate having higher thermal conductivity than glass. The mounting method is a method of pasting with an adhesive such as silicone resin, a method of sintering the light conversion member and the high thermal conductivity substrate, or extremely increasing the flatness of each substrate to lower the melting point or softening point of the material or less. 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. Preferably it is 220 micrometers or less.

  The planar shape of the 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 leakage from the light source. Since the light source is generally rectangular or circular, the light conversion member is also preferably rectangular or circular. The light converting member is preferably plate-shaped, that is, the cross-sectional shape is rectangular. The smaller the variation in the plate thickness within the light conversion member, the smaller the in-plane color variation, 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 in the light conversion member, the phosphor particles are preferably more than 15% and 40% or less, and the glass is preferably 60% or more and less than 85%.

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

  In the present light conversion member, a predetermined heat-resistant filler may be further dispersed in the glass. Thus, by containing a heat-resistant filler, the shrinkage | contraction at the time of baking can be suppressed and the dispersion state of fluorescent substance can be made uniform. When the phosphor can be uniformly dispersed in this way, the color variation of the converted light emitted from the light conversion member to the outside can be reduced, and light having a stable desired color can be obtained.

  When using a heat-resistant filler for the present light conversion member, any material having heat resistance with respect to the firing temperature at the time of production of the light conversion member may be used, and examples thereof include alumina, zirconia, magnesia, and the like. You may contain 1 or more types.

  As described above, when the phosphor particles and the heat-resistant filler are dispersed in the glass, there is an effect of sufficiently suppressing the shrinkage at the time of firing the light conversion member. For that purpose, 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 0.1 to 30% of heat-resistant filler in volume fraction. If this content is less than 0.1%, shrinkage may not be sufficiently suppressed, and if it exceeds 30%, the light transmittance of the light conversion member may be reduced, and the light source utilization efficiency may be reduced. 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 setting it as such content, the light transmittance of the light from the light source and the light conversion amount of the phosphor particles can be manufactured in a well-balanced manner as the light conversion member, and the shrinkage at the time of manufacture is suppressed, and the light is converted. The occurrence of unevenness in conversion chromaticity can be suppressed.

  When a 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 less chromaticity unevenness can be obtained. Furthermore, since the light transmittance of the light conversion member can be maintained high, the light emission conversion efficiency can be improved while maintaining the light flux amount.

[Production Method of Light Conversion Member]
The light conversion member is preferably composed of a sintered body of glass powder and phosphor particles, and if necessary, a mixed powder of heat-resistant filler. The light conversion member is more preferably a sintered body obtained by firing a slurry obtained by kneading the mixed powder, a resin, and an organic solvent. The slurry is applied to a transparent resin and dried. More preferably, the green sheet is made of a glass sheet obtained by sintering. In the present specification, the mixture of the resin and the organic solvent may be referred to as a vehicle.

  Thus, in order to produce the present light conversion member as a sintered body, a glass powder, phosphor particles, a resin and an organic solvent, and a kneading step of kneading a heat-resistant filler as necessary, to obtain a slurry, are obtained. The forming step of forming the slurry into a desired shape and the baking step of baking the formed slurry to form a light conversion member may be sequentially performed.

(Kneading process)
The kneading step in the present invention involves kneading glass powder, phosphor particles, a resin and an organic solvent, and, if necessary, a heat-resistant filler to form a slurry, and it is sufficient that these raw materials can be kneaded uniformly. In this kneading, a known kneading method, for example, kneading using a dissolver, homomixer, kneader, roll mill, sand mill, attritor, ball mill, vibrator mill, high-speed impeller mill, ultrasonic homogenizer, shaker, etc. Good. In addition, when making a light conversion member contain a heat resistant filler, what is necessary is just to mix a heat resistant filler as a raw material component simultaneously in the said kneading | mixing process, and to obtain a slurry.

  The glass powder used here may be prepared by mixing a plurality of known glass powders so as to satisfy the above-mentioned glass composition, or by mixing and mixing components so as to have predetermined thermal characteristics. Then, it may be prepared by melting in an electric furnace or the like, rapidly cooling to produce glass having a predetermined composition, pulverizing and classifying it.

In this case the 50% particle size _{D 50} of the glass powder is preferably less than 3.5 [mu] m. When the 50% particle size D ₅₀ is 3.5 μm or more, the phosphor particles and the heat-resistant filler are not uniformly dispersed in the glass powder, and the light conversion efficiency decreases when the light conversion member is used, or the shrinkage amount during firing May increase. 50% particle diameter _{D 50} is more preferably 2.5μm or less, more preferably not more than 1.9 .mu.m.

The maximum particle diameter _Dmax of the glass powder is preferably 30 μm or less. When the maximum particle size D _max is more than 30 μm, the phosphor particles and the heat-resistant filler are difficult to be uniformly dispersed in the glass powder, and when the light conversion member is produced, the light conversion efficiency of the phosphor is reduced, or during firing. There is a risk that the amount of shrinkage of the material increases. D _max is more preferably 20 μm or less, and 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 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 and the like 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 a butyral resin, a melamine resin, an alkyd resin, a rosin resin, or the like.

  When kneading the above components, the phosphor particles and the glass powder may be mixed so that the mixing ratio of the phosphor and glass in the light conversion member is in 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 the volume fraction, the phosphor particles are more than 15% and 40% or less, and the glass powder Is preferably 60% or more and less than 85%.

  In addition, when mixing the heat-resistant filler, 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 the 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 contained in less than 85%, it is possible to mainly irradiate the converted light to the outside without substantially irradiating the light source light to the outside.

  If the volume fraction of the phosphor particles is more than 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. Furthermore, the light transmittance of the light converting member may be lowered. Moreover, there is a possibility that light of a desired color cannot be obtained due to an increase in converted fluorescent light.

  Moreover, it is preferable that the volume fraction of the heat-resistant filler is 0.1% or more, since the shrinkage during firing of the light conversion member can be efficiently suppressed, and the state in which the phosphor particles are uniformly dispersed can be maintained. On the other hand, if the volume fraction of the heat resistant filler exceeds 30%, the sinterability of the mixed powder is impaired, voids inside the sintered body increase, and the light transmittance of the light conversion member may be lowered.

  A vehicle composed of a resin and an organic solvent may be made into a slurry by mixing the above mixed powder with an amount of viscosity that can be molded into a predetermined shape in the next molding step.

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

  The green sheet can be manufactured, for example, by the following process. Glass powder, phosphor particles and heat-resistant filler are kneaded in a vehicle and defoamed to obtain a slurry. The obtained slurry is coated on 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). Furthermore, by pressing these to form a laminate, a molded body having a desired thickness can be secured.

  Here, as a resin film which applies a slurry, if it has peelability, it will not specifically limit. The resin film used here is preferably one 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. .

(Baking process)
The firing step of the present invention is a step of sintering the molded slurry obtained in the molding step to form a light conversion member. Firing in this firing step is to obtain a glass containing phosphor particles and heat-resistant filler dispersed by sintering the mixed powder, and a sintered glass body may be produced by a known firing method.

The conditions for the firing step are not particularly limited as long as the sintered glass body can be obtained by firing. In order to reduce the encapsulated foam, 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%. Moreover, the maximum temperature of the calcination temperature in this process shall be 700 degrees C or less, and this maximum temperature has the preferable range of 500-700 degreeC. The firing time is preferably in the range of 0.5 to 10 hours. In the manufacturing method of the light conversion member of this invention, when implemented outside the said range, there exists a possibility that the quantum yield of a light conversion member may fall.

  The obtained light conversion member can be polished to enhance surface flatness and adhesion to the substrate. 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, more preferably 0.1 μm or less in the JIS-B0601 surface roughness defined in JIS2001. In order to improve productivity, it is also conceivable to polish only the side bonded to the substrate.

[Light source]
The illumination light source according to the present invention includes the 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. The light conversion member is preferably disposed in contact with the light source because it prevents light leakage. Moreover, as a light source, an LED light emitting element is preferable and a blue LED light emitting element is more preferable. If an LED light emitting element is used as a light source, it can be used as an LED illumination light source.

  One embodiment 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 recess, an LED 12 disposed at the center of the recess, and a light conversion member 13 disposed so as to cover the recess 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. The substrate 11 has a recess for arranging and fixing the LED in order to package the LED.

  The LED 12 is arranged and fixed at 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, thereby sealing the LED 12. Therefore, the light emitted from the LED 12 is reflected directly or reflected on the substrate 11, then travels toward the opening side of the substrate 11 and passes through the light conversion member 13. At this time, the wavelength of the light passing through the light conversion member 13 is converted by the phosphor particles inside the light conversion member 13 to become converted light, and the obtained converted light is irradiated to the outside.

Another embodiment of the illumination light source of the present invention is the illumination light source shown in FIG. The same members as those in FIG. 1 are denoted by the same reference numerals as those 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. In this embodiment, the point that the light conversion member 13 is provided on the LED 12 is different from the illumination light source shown in FIG. 1, and at this time, the LED 12 and the light conversion member 13 are fixed with an adhesive. As the adhesive used here, an adhesive having high light transmittance after solidification is used. As the substrate and the LED, the same materials as those described in the illumination light source shown in FIG. 1 can be used.

Still another embodiment of the illumination light source of the present invention is the illumination light source shown in FIG. FIG. 3 is an example using reflected light obtained by reflecting light emitted from an LED by a light conversion member. The same members as those in FIG. 1 are denoted by the same reference numerals as those in FIG. The illumination light source 20 shown in FIG. 3 is disposed at an angle such that light emitted from the LED 12 is obliquely incident on a substrate 11 having a recess, the LED 12 disposed in the center of the recess, and a position far away from the LED 12. And a lens 21 disposed 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 arbitrary members 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 into light by converting the wavelength by the phosphor particles in the light conversion member 13, and part of the light is converted into light. The light is transmitted through the light conversion member 13 and partially reflected to become reflected light L ′.

Further, as another embodiment of the illumination light source of the present invention, the illumination light source shown in FIG. FIG. 4 shows an example in which a laser is used as a light source and reflected light reflected by a 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 disposed at an angle at which the light from the laser diode 31 is incident obliquely at a position away from the laser diode 31. 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.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, a comparative example, and a reference example, this invention is limited to these Examples and is not interpreted. In addition, Example 1 described below is a reference example showing the production, characteristics, and the like of the glass prepared in manufacturing the light conversion member (Examples 1-1 to 1-26 are reference examples for implementation, Example 1-27). -1-37 are comparative reference examples), and these are collectively shown in Tables 1-2. Here, the embodiment reference example shows a glass that falls within the range of the glass composition of the light conversion member, and the comparative reference example shows a glass that does not fall within the range of the glass composition of the light conversion member. In addition, "-" of Tables 1-2 shows that it is not evaluated.

In addition, Example 2 described below includes Examples (Examples 2-1 to 2-8, Examples 2-12 to 18) and Comparative Examples (Examples 2-9 to 2-11, Examples 2-19 to Examples). 2-21).

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

The resulting glass ribbon was pulverized with a ball mill, by passing a # 100 mesh sieve, in each example of Examples 1-1 to Example 1-37, the 50% particle size _{D 50} of 3μm powder (glass powder) Got.

The glass transition point Tg of the glass of each example was measured using a differential thermal analyzer (trade name: TG8110, manufactured by Rigaku Corporation). Further, the 50% particle size _{D 50} of the glass powder, a laser diffraction particle size distribution measurement (manufactured by Shimadzu Corporation, apparatus name: SALD2300) was calculated by.
The thermal expansion coefficient (CTE) of glass was calculated | required as an average linear thermal expansion coefficient (* 10 < ^-7 >) of 50-350 degreeC with the thermomechanical analyzer (TMA).
The specific gravity d was measured by the Archimedes method using the glass plate obtained in each example.
In addition, the thermal expansion coefficient and specific gravity in Examples 1-15 to 1-18 are values calculated by calculation from the glass composition.

  Sinterability was evaluated as follows. First, about 3 g of the glass powder obtained in each example was molded into a green compact, and this was heated to a firing temperature described in Tables 1-2 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 fired body obtained was fluidized after firing, and the fired body with rounded corners and vitreous gloss was evaluated as “◯”, and the others were evaluated as “x”.

  The water resistance was tested by exposing 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 having a thickness of 1 mm and a size of 20 mm × 20 mm, and then both surfaces thereof were mirror-polished.

  After 6 hours, 24 hours, and 168 hours (one week later), a sample was taken out and checked, and it was judged by whether or not 5 or more white spots of 1 mm or more were deposited. The glass deposited when confirmed after 6 hours was “x”, the glass deposited when confirmed after 24 hours was “Δ”, and the glass deposited when confirmed after 168 hours was “◯”. Glasses for which precipitation could not be confirmed even after 168 hours were evaluated as “◎”.

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

[Example 2: Production of light conversion member]
(1) Next, using the glass powder obtained in Example 1, using a dry air classifier, further adjusting the particle size distribution to be a narrow distribution, the 50% particle size D ₅₀ is 1.4. The light conversion member was manufactured as follows, with a maximum particle size D _max of 21 μm or less and ˜1.6 μm. As the phosphor particles dispersed in the glass, α-SiAlON: Eu ²⁺ phosphor having a 50% particle size D ₅₀ of 16 μm and a phosphor peak wavelength of about 590 nm when excited at 450 nm was used. Further, 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 and the glass obtained in Example 1-2 is glass 2. As shown, the glass numbers up to the glass 37 are described.

  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 Limited) 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 baking atmosphere was set to the atmospheric baking at the baking temperature as shown in Table 3 to produce the light conversion members of Examples 2-1 to 2-8. The thickness of the obtained light conversion member was about 0.2 mm. Firing conditions were as follows: the temperature was raised to the firing temperature shown in Table 3 at a rate of 10 ° C./minute, and then kept at the firing temperature for 30 minutes, and then the heater of the electric furnace was turned off and allowed to cool.

  About the obtained light conversion member of Examples 2-1 to 2-8, the package for a test was produced and each characteristic of a quantum yield and a brightness fall was measured and evaluated. The test package is a light of 1 mm □ × 200 μm in thickness through a silicone adhesive (made by Shin-Etsu Chemical Co., Ltd.) on an LED (made by Cree, trade name: EZ1000) in the center of a recessed part of a glass ceramic substrate having a recessed part. A conversion member laminated and adhered was placed and obtained.

  For the quantum yield of the light conversion member, the central portion of the obtained light conversion member is cut into a size of 1 cm square, and an absolute PL quantum yield measurement device (manufactured by Hamamatsu Photonics, trade name: Quantauru-QY) is used. The measurement was performed at an excitation light wavelength of 450 nm.

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

  The brightness reduction amount measurement test of the light conversion member was calculated by passing a current of 750 mA to the LED, performing a test for 200 hours in a test environment at 100 ° C., and measuring the change (decrease) in the total luminous flux 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 a light conversion member was obtained by the same operation as in Example 2 using this glass. The sinterability and water resistance of the glass composition shown in Table 4 were good. About the obtained light conversion member, when the quantum yield and the luminance reduction were examined by the same operation as in Example 2, the quantum yield was good, but the luminance reduction was remarkable and the life was short. I understood it. When the sample after the test was analyzed by STEM, a metal colloid of bismuth was confirmed at the interface between the phosphor particles and the glass. This is because the vibration energy corresponding to the Stokes shift that remains in the photoexcited phosphor accumulates in the vicinity of the phosphor and generates heat, and finally, the light conversion member is constituted by the action caused by the light of the blue LED. It is thought that the glass was reduced and colloid was formed. It seems that the brightness has decreased due to the coloring.

  (3) Further, the phosphor content, thickness, and firing temperature of Glass 1 and Glass 19 were set as shown in Table 5 to obtain a light conversion member by the same operation as in Example 2. The LED light absorptivity of the obtained light conversion member was calculated and summarized in Table 5.

LED light absorptivity is arranged in the center of the concave portion of a glass ceramic substrate having a concave portion, an LED (made by Cree, trade name: EZ1000) is disposed, and a light conversion member having a substrate size of 5 to 7 mm square so as to cover the LED. Using what was arranged, it calculated like the following formula.

LED light absorptivity = [LED light intensity−blue conversion intensity of light conversion member] / LED light intensity

(In the formula, [LED light intensity] and [blue missing intensity of light converting member] are values obtained by integrating light intensities of 410 nm to 490 nm.)

  As is apparent from Tables 3 to 5, the light conversion member of the present invention is composed of glass powder and phosphor particles having a specific glass composition, and is sufficiently fired even if the phosphor particles contain more than 15% by volume. In addition, the luminance reduction can be suppressed 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 quantum yield of 85% or higher, and by containing a large amount of phosphor particles, the absorption rate of LED light serving as a light source is very excellent at 98% or higher. I found out that it would be a thing.

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

The photoexcited phosphor undergoes a radiation transition from the electronically excited state to the ground state with vibrational relaxation. At this time, vibration energy corresponding to the Stokes shift remains in the vicinity of the phosphor and generates heat. At this time, the glass containing Bi ₂ O ₃ slightly absorbs light of 450 nm and generates heat in the vicinity of the phosphor. However, the glass becomes higher due to the above cause, and the glass is reduced by the action caused by light, It is considered that the brightness was lowered due to colloidal coloring. This is considered to be the same in the glass containing PbO.

  On the other hand, in the glass composition of the present invention, the above-mentioned problem of colloid formation hardly occurs, the luminance is hardly lowered, and an excellent light conversion member can be obtained.

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

DESCRIPTION OF SYMBOLS 10,20,30 ... Illumination light source, 11 ... Board | 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 is expressed in mol% on the basis of oxide, SiO ₂ 0-40%, B ₂ O ₃ 10-45%, Al ₂ O ₃ 0-10%, ZnO 25-64%, alkaline earth metal oxide. (MgO + CaO + SrO + BaO) 0 to 30%, 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 A 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 or 2, wherein the ZnO is 40% or more. The light conversion member according to claim 1, wherein the B ₂ O ₃ is 35% or less.   The phosphor particles are one or more compounds having an excitation band at a wavelength of 400 to 500 nm, an emission peak at a wavelength of 500 to 700 nm, and selected from the group consisting of oxides, nitrides, and oxynitrides. 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 at a wavelength of 450 nm at a thickness of 1 mm of the glass of 80% or more.   An illumination light source comprising: the light conversion member according to claim 1; 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, resin and organic solvent into a slurry, a molding step of molding the obtained slurry into a desired shape, and firing the molded slurry to obtain a light conversion member A method for producing a light conversion member having 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 and kneaded to obtain a slurry.

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