WO2014050684A1

WO2014050684A1 - Glass composition for phosphor-dispersed glass sheets, and phosphor-dispersed glass sheet using same

Info

Publication number: WO2014050684A1
Application number: PCT/JP2013/075258
Authority: WO
Inventors: 谷田　正道; 英樹沼倉
Original assignee: 旭硝子株式会社
Priority date: 2012-09-25
Filing date: 2013-09-19
Publication date: 2014-04-03
Also published as: JP2015227252A

Abstract

The present invention relates to a glass composition for phosphor-dispersed glass sheets, which contains a glass powder and a phosphor powder, and wherein the difference (∆ Tgs) between Ts and Tg that are calculated from the DTA curve of the glass powder is 50-105°C.

Description

Glass composition for phosphor-dispersed glass sheet and phosphor-dispersed glass sheet using the same

The present invention relates to a glass composition for a phosphor-dispersed glass sheet and a phosphor-dispersed glass sheet produced using the same, and more particularly, converts blue light from a blue light source, particularly a blue light-emitting diode (LED) element, into white light. It is related with the light conversion member for doing.

White LEDs are used as a low-power white illumination light source, and are expected to be applied to illumination applications. The white light of the white LED is obtained by synthesizing blue light emitted from a blue LED element and yellow light obtained by converting a part of the blue light into yellow with a phosphor.

Conventionally, as a light conversion member, a phosphor-dispersed glass sheet (hereinafter also referred to as a glass sheet) having an inorganic phosphor dispersed in glass is known (for example, Patent Document 1). By adopting such a configuration, the high transmittance of the glass can be used, and furthermore, the heat generated from the element can be efficiently released to the outside of the member. Moreover, the damage of the member by light and a heat | fever is also low, and long-term reliability is acquired.

The glass sheet is produced by mixing glass powder and phosphor powder and firing the mixture. Conventionally, there has been a problem that bubbles generated in the baking process remain in the glass. If there are bubbles in the glass (hereinafter referred to as encapsulated bubbles), the transmittance of the glass is lowered, causing a reduction in the luminous efficiency of the LED. In addition, the encapsulated foam may cause light to scatter in the glass and reduce the amount of light striking the phosphor.

Patent Document 2 describes a method of using a SiO ₂ —B ₂ O ₃ based glass and a SnO—P ₂ O ₅ based glass and performing a firing step under reduced pressure in order to reduce encapsulated bubbles. . However, in the baking under a reduced pressure atmosphere, the encapsulated foam can be reduced, but depending on the glass composition, the component may be volatilized. Further, in a glass having a high softening point such as SiO ₂ —B ₂ O ₃ glass, the firing temperature becomes high, and the phosphor may be deteriorated.

Japanese Unexamined Patent Publication No. 2003-258308 Japanese Laid-Open Patent Publication No. 2007-311743

In view of the above problems, the present inventors use a glass having a low glass softening point, thereby lowering the firing temperature to prevent the phosphor from being deteriorated, and exhibiting a glass having a steep viscosity curve in the firing temperature range. It has been found that the encapsulated foam in the glass sheet after firing can be reduced by using it, and the present invention has been achieved.
That is, the present invention provides a glass composition capable of producing a phosphor-dispersed glass sheet with low encapsulated foam and high transmittance at a low temperature, and a phosphor-dispersed glass sheet obtained by firing the glass composition. The purpose is to provide.

The glass composition of the present invention is a glass composition for a phosphor-dispersed glass sheet containing glass powder and phosphor powder, and the difference (ΔTgs) between Ts and Tg calculated from the DTA curve of the glass powder is 50 to 105 ° C. The glass composition of the present invention is also a glass composition for a phosphor-dispersed glass sheet containing a glass powder and a phosphor powder, and the glass powder is a difference between Tc and Tg calculated from a DTA curve. (ΔTgc) is 95 ° C. or higher. Furthermore, a glass composition for a phosphor-dispersed glass sheet containing glass powder and phosphor powder, wherein the glass powder has a difference (ΔTgs) between Ts and Tg calculated from a DTA curve of 50 to 105 ° C. And the difference (ΔTgc) between Tc and Tg calculated from the DTA curve is 95 ° C. or higher.

The phosphor-dispersed glass sheet of the present invention is produced by firing the glass composition for a phosphor-dispersed glass sheet of the present invention.

The glass composition for a phosphor-dispersed glass sheet of the present invention can lower the firing temperature, and can further reduce the encapsulated foam of the glass sheet after firing. Due to the low temperature firing, it is possible to suppress the deterioration of the phosphor in the manufacturing process. Furthermore, light scattering inside the glass sheet can be suppressed, the transmittance of the glass sheet can be increased, and the luminous efficiency of the LED can be increased.

FIG. 1 is a schematic cross-sectional view of a phosphor-dispersed glass sheet.

The influence of the presence of bubbles contained in the glass sheet on the light emission efficiency of the LED will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of a phosphor-dispersed glass sheet 2 on an LED light-emitting element 1.

FIG. 1A shows a case where there is no encapsulated bubble around the phosphor 3 and between the LED light emitting element 1 and the phosphor 3. Since the LED light 5 emitted from the LED light emitting element 1 is not scattered in the phosphor-dispersed glass sheet 2, the decrease in the amount of light passing through the phosphor-dispersed glass sheet 2 is small. Therefore, the luminous efficiency of the LED is high. Further, the LED light 5 emitted from the LED light emitting element 1 efficiently hits the phosphor 3 and is converted into fluorescence 7. Therefore, a decrease in the conversion efficiency of the phosphor 3 is small.

FIG. 1B shows the case where the encapsulated foam 4 is in contact with the phosphor 3. In this case, light is easily reflected at the interface between the encapsulated bubble 4 and the glass 6, and the LED light 5 partially becomes scattered light 8. Furthermore, when the encapsulated foam 4 is present, multiple scattering tends to occur within the phosphor-dispersed glass sheet 2. When multiple scattering is performed, the optical path length becomes long, light is attenuated in the phosphor-dispersed glass sheet 2, the amount of light transmitted through the phosphor-dispersed glass sheet 2 is reduced, and the light emission efficiency of the LED may be lowered. Further, when the amount of light hitting the phosphor 3 is reduced, the amount of the fluorescence 7 is reduced, and the conversion efficiency may be reduced.

FIG. 1 (c) shows a case where there is an encapsulated bubble, but there is an encapsulated bubble 4 between the LED light emitting element 1 and the phosphor 3 without contacting the phosphor 3. Similar to FIG. 1B, the LED light 5 is reflected at the interface when entering the encapsulating bubble 4 from the glass 6 and when exiting the encapsulating bubble 4 to the glass 6. That is, the LED light 5 is scattered and part of the encapsulated foam 4 becomes scattered light 8. When light is scattered in the phosphor-dispersed glass sheet 2, the light emission efficiency of the LED may be reduced as in the case of FIG. Further, when the amount of light hitting the phosphor 3 is reduced, the amount of the fluorescence 7 is reduced, and the conversion efficiency may be reduced.

LED light 5 and fluorescence 7 emitted from the LED light emitting element 1 are transmitted through the phosphor-dispersed glass sheet 2 and emitted. When these light is subjected to multiple scattering and back reflection by the encapsulated bubbles, there is a possibility that the light is attenuated in the phosphor-dispersed glass sheet 2. The degree of multiple scattering and back reflection can be evaluated by the total light transmittance. That is, if excessive multiple scattering and back reflection do not occur, the total light transmittance is high, and the loss of light while passing through the phosphor-dispersed glass sheet 2 is small.

From the above, if the encapsulated foam 4 is present in the phosphor-dispersed glass sheet 2, the light is attenuated in the phosphor-dispersed glass sheet 2 and the transmittance is lowered, and the light hitting the phosphor 3 is reduced and the phosphor is reduced. Conversion efficiency decreases. Thereby, the luminous efficiency of LED falls. Therefore, the LED conversion member is required to reduce the encapsulated bubbles 4 of the phosphor-dispersed glass sheet 2.

Next, an embodiment of the glass composition of the present invention (hereinafter referred to as the present glass composition) will be described. The glass powder contained in the present glass composition has the characteristics that the rate of change in viscosity at the softening point is large and the viscosity curve is steep. Since such glass powder has low glass viscosity at the firing temperature, it can be sufficiently defoamed in the firing step. Further, it is necessary that the glass powder does not have a crystallization point Tc or the crystallization point Tc is sufficiently higher than the glass transition point Tg. When the crystallization point Tc is in the vicinity of the glass transition point Tg, the viscosity of the glass is not lowered at the firing temperature, and sufficient defoaming cannot be performed in the firing step.

In the present invention, the rate of change of the viscosity curve at the softening point of the glass powder is evaluated by the magnitude of the difference ΔTgs between the glass softening point Ts and the glass transition point Tg measured by DTA (differential thermal analysis). Ts and Tg are both temperatures determined by the viscosity of the glass. Specifically, Ts is a temperature at which the viscosity of the glass is 10 ^7.5 dPa · s, and Tg is a temperature at which the viscosity of the glass is about 10 ^13.3 dPa · s. Therefore, the smaller the ΔTgs, the greater the rate of change in viscosity and the steeper curve.

The ΔTgs of the glass powder used in the present glass composition is 50 to 105 ° C. If ΔTgs is less than 50 ° C., the glass may become unstable. On the other hand, if ΔTgs exceeds 105 ° C., the encapsulated foam of the glass sheet after firing may increase. ΔTgs is preferably 80 to 100 ° C., and more preferably 85 to 95 ° C.

The Ts of the glass powder is preferably 700 ° C. or lower. If Ts is high, the firing temperature becomes high, and thus the phosphor powder may be deteriorated in the firing step. Ts is more preferably 650 ° C. or lower, and further preferably 620 ° C. or lower.

The crystallization point Tc of the glass powder is an exothermic peak at a temperature equal to or higher than the glass transition point Tg measured by DTA. When glass is crystallized, the overall viscosity increases rapidly, and there is a risk that the encapsulated bubbles in the glass sheet after firing increase. The larger the difference ΔTgc between Tc and Tg, the more difficult it is to crystallize, and it is useful in the present invention. ΔTgc of the glass powder used in the present glass composition is 95 ° C. or higher. ΔTgc is preferably 100 ° C. or higher, more preferably 105 ° C. or higher.

Examples of the glass having Ts, Tg, and ΔTgs in the above-described range include a glass mainly containing a Bi ₂ O ₃ —ZnO—B ₂ O ₃ system. Among them, a glass containing Bi ₂ O ₃ 3 to 30%, B ₂ O ₃ 10 to 50%, and ZnO 0 to 45% in terms of mol% based on oxide is more preferable. Bi ₂ O ₃ 3-30%, B ₂ O ₃ 10-50%, ZnO 0-45%, SiO ₂ 5-35%, BaO 0-20%, MnO ₂ 0-1%, CeO ₂ 0-1% The glass containing is more preferable. The glass mainly composed of Bi ₂ O ₃ —ZnO—B ₂ O ₃ includes Bi ₂ O ₃ 3 to 30%, B ₂ O ₃ 10 to 50%, ZnO 0 to 45%, SiO ₂ 5 to 35. %, BaO 0-20%, MnO ₂ 0-1%, CeO ₂ 0-1%. In the present specification, “consisting essentially of” means that inevitable impurities other than the components described are allowed. Further, such a composition is preferable because Tc and ΔTgc are also in the above ranges.

Bi ₂ O ₃ is a component that lowers Ts without lowering the chemical durability of glass, and is an essential component in this system. The content of Bi ₂ O ₃ is preferably 3 to 30%. If Bi ₂ O ₃ is less than 3%, Ts of the glass powder becomes high, which is not preferable. On the other hand, if it exceeds 30%, the glass becomes unstable, tends to crystallize, and the sinterability may be impaired. The content of Bi ₂ O ₃ is more preferably 5 to 25%, further preferably 5 to 20%.

B ₂ O ₃ is a glass network former and is a component that can stabilize glass, and is an essential component in this system. The content of B ₂ O ₃ is preferably 10 to 50%. 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 50%, the chemical durability of the glass may be lowered. The content of B ₂ O ₃ is more preferably 15 to 45%, further preferably 20 to 45%.

ZnO is a component that lowers Ts and is not an essential component in this system. The content of ZnO is preferably 0 to 45%. If the ZnO content exceeds 45%, it will be difficult to vitrify, and it will be difficult to produce glass. The lower limit of the ZnO content is more preferably 5% or more, and further preferably 10% or more. Further, the upper limit is more preferably 40% or less, and further preferably 35% or less.

SiO ₂ is a component that increases the stability of the glass and is not an essential component in this system. The content of SiO ₂ is preferably 0 to 35%. If the SiO ₂ content exceeds 35%, Ts may be high. The lower limit of the content of SiO ₂ is more preferably 5% or more, and further preferably 10% or more. The upper limit is more preferably 30% or less, and further preferably 25% or less.

CaO, SrO, MgO or BaO alkaline earth metal oxide is a component that increases the stability of the glass and lowers Ts, and is not an essential component in this system. The total amount of alkaline earth metal oxide is preferably 0 to 20%. If the total amount exceeds 20%, the stability of the glass is lowered. More preferably, the total amount is 18% or less. Further, BaO is preferable as the alkaline earth metal oxide.

Neither MnO ₂ nor CeO ₂ is an essential component in this system, but since it functions as an oxidizing agent in the glass, it is preferably contained in the glass. In any case, reduction of Bi ₂ O ₃ in the glass can be prevented, so that this type of glass can be stabilized. Reduction of Bi ₂ O ₃ is not preferable because the glass is colored. Furthermore, the encapsulated foam of the glass sheet after baking may increase. The contents of MnO ₂ and CeO ₂ are each preferably 0 to 1%. If the content exceeds 1%, coloring may increase.

Components are prepared and mixed so as to have predetermined thermal characteristics, melted in an electric furnace or the like, and rapidly cooled to produce glass. The glass powder is produced by pulverizing and classifying the glass. Particle diameter of the glass powder is indicated by the 50% particle diameter _{D 50.} 50% particle diameter _{D 50} is preferably less than 2.0 .mu.m. D ₅₀ is 2.0μm or more, the phosphor powder is not uniformly dispersed in the glass powder, it may decrease the conversion efficiency when the glass sheet. D ₅₀ is more preferably 1.5 μm or less, and still more preferably 1.4 μm or less.

The maximum particle size Dmax of the glass powder is preferably 30 μm or less. When Dmax is more than 30 μm, the phosphor powder is not uniformly dispersed in the glass powder, and when the glass sheet is produced, the conversion efficiency of the phosphor may be lowered. Dmax is more preferably 20 μm or less, and still more preferably 15 μm or less.
In the present specification, both D ₅₀ and Dmax is a value calculated by a laser diffraction type particle size distribution measurement.

The phosphor powder used in the present glass composition is not limited as long as it can convert blue light into yellow light. Examples of phosphors include oxides, nitrides, oxynitrides, sulfides, oxysulfides, halides, aluminate chlorides, or halophosphates, and particularly have an excitation band at a wavelength of 400 to 500 nm. Those having an emission peak at a wavelength of 500 to 700 nm are preferable.

When the excitation light is blue light having a wavelength of 440 to 480 nm, the phosphors are (Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Y, Lu) ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Y, Gd ) ₃ (Al, Ga) ₅ O ₁₂ : Ce ³⁺ , Ba ₅ (PO ₄ ) ₃ Cl: U, CaGa ₂ S ₄ : Eu ²⁺ is preferable. Among them, (Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ or (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce ³⁺ is more preferable.

50% particle diameter _{D 50} of the phosphor powder is preferably 15μm or less. If D ₅₀ of the phosphor powder becomes large, the dispersion becomes poor glass sheet after firing, the conversion efficiency of light is degraded. D ₅₀ is more preferably 13 μm or less, and further preferably 10 μm or less.

In the present glass composition, in addition to the glass powder and the phosphor powder, the glass composition may further include those capable of degassing the encapsulated foam. Examples of such elements include elements that can have a plurality of oxidation numbers by changing the valence, such as metal compounds having oxidation catalytic properties such as copper chloride and antimony oxide. On the other hand, from the viewpoint of production cost, the present glass composition is preferably composed of glass powder and phosphor powder.

In the case where the present glass composition is composed of glass powder and phosphor powder, the mixing ratio of the glass powder and phosphor powder is volume%, glass powder 60 to 99.99%, phosphor powder 0.01 ~ 40% is preferred. If the volume ratio of the glass powder is less than 60%, the sinterability of the mixture of the glass powder and the phosphor powder may be impaired, and the transmittance of the glass sheet may be lowered. Moreover, there is a possibility that yellow light increases and desired white light cannot be obtained. On the other hand, if the phosphor powder is less than 0.01%, the blue light cannot be sufficiently converted, and when the LED is used, desired white light may not be obtained. The mixing ratio is more preferably 70 to 95% glass powder and 5 to 30% phosphor powder, more preferably 80 to 90% glass powder and 10 to 20% phosphor powder.

The glass sheet is manufactured through the molding process and the firing process using the present glass composition. The molding method is not particularly limited as long as a desired shape can be imparted. Examples thereof include a press molding method, a roll molding method, and a doctor blade molding method. A green sheet manufactured by a doctor blade molding method is preferable because a glass sheet having a uniform film thickness can be efficiently manufactured in a large area.

The green sheet can be manufactured, for example, by the following process. Glass powder and phosphor powder are kneaded in a vehicle and defoamed to obtain a slurry. The slurry is prepared on a transparent resin by a doctor blade method and dried. After drying, it is cut into a desired size and the transparent resin is peeled off to obtain a green sheet. Furthermore, a desired thickness can be ensured by pressing them into a laminate.

The vehicle is obtained by dissolving a resin (binder) in an organic solvent. As the resin, ethyl cellulose, nitrocellulose, acrylic resin, vinyl acetate resin, butyral resin, melamine resin, alkyd resin, rosin resin and the like can be used. As the organic solvent, toluene, xylene, propanol, butanol, butyl acetate, methyl ethyl ketone, and the like can be used. In addition, when the vehicle contains a butyral resin, a melamine resin, an alkyd resin, or a rosin resin, the strength of the green sheet is improved, which is preferable.

The transparent resin for applying the slurry is not limited as long as a green sheet with a uniform film thickness is obtained. For example, a PET film etc. are mentioned.

When the glass sheet is produced, the firing temperature is 450 to 900 ° C., and the glass softening point Ts ± 50 ° C. is preferable. Usually, when glass powder is fired to form a sintered body, the encapsulated foam of the glass sheet can be reduced by setting the firing temperature in the vicinity of Ts. When fired at a temperature higher than Ts + 50 ° C., the encapsulated foam increases, and the phosphor powder may be deteriorated by reaction with heat or glass, and the conversion efficiency of the phosphor may be reduced. On the other hand, when fired at a temperature lower than Ts-50 ° C., the encapsulated foam of the glass sheet cannot be sufficiently reduced. The firing temperature is more preferably Ts ± 30 ° C., further preferably Ts ± 20 ° C.

When Bi ₂ O ₃ —ZnO—B ₂ O ₃ based glass is used, Ts is preferably 530 to 630 ° C. Therefore, the firing temperature is preferably 480 to 680 ° C. The firing temperature is more preferably 500 to 660 ° C., and further preferably 530 to 630 ° C.

The firing atmosphere is not particularly limited. If the ΔTgs of the glass is within the range of the present invention, the encapsulated bubbles of the glass sheet can be sufficiently reduced even in the atmosphere, and the conversion efficiency of the phosphor can be increased.

In addition, when firing using an electric furnace, it is preferable to perform in two stages: debinder firing for removing the binder in the vehicle and main firing for sintering the glass powder.

¡Binder removal depends on the type and amount of binder in the vehicle used to manufacture the green sheet. For example, it is preferable to use an electric furnace or the like and hold at 400 to 480 ° C. for 1 to 6 hours.

A glass sheet produced from the present glass composition is useful as a light conversion member because it contains less encapsulated foam and can increase the conversion efficiency of the phosphor.
Since the glass sheet manufactured from the present glass composition can maintain a high quantum conversion yield, the function of the light conversion member can be exhibited even if it is thin. The thickness of the glass sheet is preferably 50 to 500 μm. When the thickness is 50 μm or more, handling becomes easy, and cracking can be suppressed particularly when cutting into a desired size. The thickness is more preferably 80 μm or more, further preferably 100 μm or more, and particularly preferably 120 μm or more. If the thickness is 500 μm or less, the total amount of transmitted light can be kept high. The thickness is preferably 400 μm or less, more preferably 300 μm or less, and particularly preferably 250 μm or less.

The planar shape of the glass sheet is not particularly limited. For example, when used as a light conversion member in contact with a light source, it is manufactured in accordance with 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, a rectangular or circular shape is preferable.

Since the amount of encapsulated foam in the glass sheet has a positive correlation with the porosity, the amount of encapsulated foam can be evaluated by the porosity. The porosity of the glass sheet is preferably 5% or less. If the porosity exceeds 5%, the encapsulated bubbles in the glass sheet are large, and light is likely to be scattered inside the glass sheet. The porosity is preferably as low as possible, more preferably 2.5% or less, and even more preferably 1% or less. In the present specification, the porosity means a value derived from the deviation of the measured specific gravity with respect to the theoretical specific gravity of the glass sheet. Specifically, the measured specific gravity is obtained by the Archimedes method. On the other hand, the theoretical specific gravity is obtained by obtaining a measured specific gravity of a glass body and a phosphor without pores by the Archimedes method and the pycnometer method, and performing synthetic calculation according to the blending.

It is preferable that the glass sheet has less internal scattering due to the encapsulated foam and less light absorption. If the glass sheet has a large amount of internal scattering, the glass becomes opaque, which is not preferable. The internal scattering of the glass sheet can be evaluated by measuring parallel light transmittance and measuring total light transmittance. In this specification, both the parallel light transmittance and the total light transmittance are values measured by a method according to JIS-K-7136 (1997).

The parallel light transmittance is preferably 4% or more, and more preferably 5% or more. If the parallel light transmittance is less than 4%, blue light that is not converted into a phosphor is scattered inside the glass sheet, and the LED issuance efficiency may be reduced.

The total light transmittance is preferably 70% or more, more preferably 75% or more, and even more preferably 80% or more. If the total light transmittance is less than 70%, the light emitted from the light emitting element is absorbed inside the glass sheet, and the luminance of the LED is lowered, that is, the luminous efficiency of the LED is not preferable.

The conversion efficiency of the phosphor in the glass sheet can be evaluated by the quantum conversion efficiency. The quantum conversion efficiency is preferably 85% or more. If it is less than 85%, the incident blue light cannot be sufficiently converted to yellow light, and the light obtained by the synthesis may not be a desired white color. The quantum conversion efficiency is more preferably 86% or more. The quantum conversion efficiency is represented by the 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 an integrating sphere method. To do.

Hereinafter, the present invention will be described based on examples. Examples 1 and 2 are examples of the present invention, and examples 3 and 4 are comparative examples.

(Example 1)
Bi ₂ O ₃ 8.9%, SiO ₂ 15.2%, B ₂ O ₃ 31%, ZnO 33.5%, BaO 11.2%, MnO ₂ 0.1% in terms of mole% based on oxide. was mixed glass raw materials such that the _CeO 2 0.1%. This was heated in a platinum crucible to 1200-1400 ° C. with an electric furnace, melted, and the melt was quenched with a rotating roll to form a glass ribbon. The glass ribbon was pulverized by a ball mill, passed through a sieve having a mesh having an opening of 150 μm, and further classified by air flow to obtain glass 1 powder (glass powder 1).

The glass transition temperature Tg and the glass softening point Ts of the obtained glass powder 1 were measured using a differential thermal analyzer (trade name: TG8110, manufactured by Rigaku Corporation). D ₅₀ and Dmax were calculated by laser diffraction particle size distribution measurement (manufactured by Shimadzu Corporation, apparatus name: SALD2100). The results are shown in Table 1.

The thus obtained glass powder 1 and YAG having a structure of (Y, Lu) ₃ Al ₅ O ₁₂ : Ce ³⁺ having a 50% particle diameter D ₅₀ of 10 μm and a phosphor peak wavelength of about 555 nm when excited at 460 nm. The phosphor powder was mixed with 84% by volume of glass powder 1 and 16% by volume of phosphor powder, kneaded with a vehicle, and defoamed to obtain a slurry. The vehicle used was 25 parts by weight of an acrylic resin dissolved in toluene, xylene, isopropanol, and 2-butanol. Further, a mixed solvent of toluene, xylene, isopropanol and 2-butanol was used as a dilution solvent, and the slurry viscosity was adjusted to about 5000 cP. 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 about 0.5 mm.

２ Two green sheets were stacked and pressed. This was placed on a mullite substrate coated with a release agent, and subjected to a binder removal baking process at 420 ° C. for 4 hours in the air, and further baking was performed at 550 ° C. under normal pressure for 1 hour to prepare a glass sheet. The thickness of the glass sheet measured with a micrometer was 135 μm. Note that the temperature of the binder removal treatment and baking is determined as a result of searching for so-called optimum conditions that provide the highest transmittance and high conversion quantum efficiency.

The porosity, quantum conversion efficiency, and transmittance of the glass sheet thus obtained were measured. These results are shown in Table 1.

The porosity of the glass sheet was measured by the Archimedes method. The quantum conversion efficiency was measured at an excitation light wavelength of 460 nm using an absolute PL quantum yield measuring apparatus (manufactured by Hamamatsu Photonics, trade name: Quantaurus-QY). The haze and transmittance of the glass sheet were measured with a C light source using a haze measuring device (trade name: Haze Meter HZ-2, manufactured by Suga Test Instruments Co., Ltd.).

(Example 2)
A green sheet was obtained by the same method as in Example 1 using glass powder 1. Two green sheets were laminated and pressed. This was placed on a mullite substrate coated with a release agent, and baked at 460 ° C. for 6 hours in the atmosphere, and further baked at 570 ° C. for 1 hour under reduced pressure (about 60 Pa) to produce a glass sheet. did. The thickness of the glass sheet measured with a micrometer was 135 μm. Note that the temperature of the binder removal treatment and baking is determined as a result of searching for so-called optimum conditions that provide the highest transmittance and high conversion quantum efficiency.

The porosity, quantum conversion efficiency, and transmittance of the obtained glass sheet were measured in the same manner as in Example 1. These results are shown in Table 1.

(Example 3)
In terms of oxide-based mol%, SiO ₂ 21%, B ₂ O ₃ 31%, ZnO 2%, Li ₂ O 16%, MgO 9%, CaO 5%, BaO ₂ %, Al ₂ O ₃ 14%. The glass raw materials were mixed as described above. This was heated in an electric furnace to 1300-1500 ° C. in a platinum crucible and melted, and the melt was quenched with a rotating roll to form a glass ribbon. The glass ribbon was pulverized with a ball mill, passed through a sieve having a mesh having an opening of 150 μm, and further subjected to air classification to obtain glass 2 powder (glass powder 2).

The characteristics of the glass were evaluated in the same manner as in Example 1. The results are shown in Table 1.

A green sheet was obtained by the same method as in Example 1 using glass powder 2. Two green sheets were laminated and pressed. This was placed on a mullite substrate coated with a release agent, and baked in a binder at 380 ° C. for 4 hours in the atmosphere, and further baked at 580 ° C. under normal pressure for 1 hour to prepare a glass sheet. The plate thickness of the glass sheet measured with a micrometer was 154 μm. Note that the temperature of the binder removal treatment and baking is determined as a result of searching for so-called optimum conditions that provide the highest transmittance and high conversion quantum efficiency. Moreover, the porosity, the quantum conversion efficiency, and the transmittance | permeability were measured by the method similar to Example 1 about the glass sheet. These results are shown in Table 1.

(Example 4)
In terms of oxide-based mol%, SiO ₂ 31%, B ₂ O ₃ 11%, ZnO 7%, Li ₂ O 21%, Na ₂ O 7%, K ₂ O 3%, BaO 4%, Al ₂ O _The glass raw materials were mixed so as to be 33%, TiO ₂ 11%, and Nb ₂ O ₅ 2%. This was heated in an electric furnace to 1300-1500 ° C. in a platinum crucible and melted, and the melt was quenched with a rotating roll to form a glass ribbon. The glass ribbon was pulverized with a ball mill, passed through a sieve having a mesh having an opening of 150 μm, and further subjected to air classification to obtain glass 3 powder (glass powder 3).

Using the glass powder 3, a green sheet was obtained by the same method as in Example 1. Two green sheets were laminated and pressed. This was placed on a mullite substrate coated with a release agent, and subjected to binder removal firing at 320 ° C. for 4 hours in the air, and further fired at 530 ° C. under normal pressure for 1 hour to prepare a glass sheet. The thickness of the glass sheet measured with a micrometer was 150 μm. Note that the temperature of the binder removal treatment and baking is determined as a result of searching for so-called optimum conditions that provide the highest transmittance and high conversion quantum efficiency. Moreover, the quantum conversion efficiency and the transmittance | permeability were measured by the method similar to Example 1 about the glass sheet. These results are shown in Table 1.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2012-210885 filed on Sep. 25, 2012, the contents of which are incorporated herein by reference.

The glass composition for a phosphor-dispersed glass sheet of the present invention can be used for producing a phosphor-dispersed glass sheet for converting a blue light source to obtain a white light source of a white LED.

1 LED light-emitting element, 2 phosphor-dispersed glass sheet, 3 phosphor, 4 encapsulated foam, 5 LED light, 6 glass, 7 fluorescence, 8 scattered light

Claims

A glass composition for a phosphor-dispersed glass sheet containing glass powder and phosphor powder, wherein the glass powder has a difference (ΔTgs) between Ts and Tg calculated from a DTA curve of 50 to 105 ° C. A glass composition for a phosphor-dispersed glass sheet.
A glass composition for a phosphor-dispersed glass sheet containing a glass powder and a phosphor powder, wherein the glass powder has a difference (ΔTgc) between Tc and Tg calculated from a DTA curve of 95 ° C. or more. A glass composition for a phosphor-dispersed glass sheet.
A glass composition for a phosphor-dispersed glass sheet comprising a glass powder and a phosphor powder, wherein the glass powder has a difference (ΔTgs) between Ts and Tg calculated from a DTA curve of 50 to 105 ° C. And the glass composition for fluorescent substance dispersion | distribution glass sheets whose difference ((DELTA) Tgc) of Tc and Tg computed from a DTA curve is 95 degreeC or more.
The glass composition for a phosphor-dispersed glass sheet according to any one of claims 1 to 3, wherein the glass powder is a Bi 2 O 3 -ZnO-B 2 O 3 glass powder.
The phosphor-dispersed glass sheet according to claim 4, wherein the glass contains Bi 2 O 3 3 to 30%, ZnO 0 to 45%, and B 2 O 3 10 to 50% in terms of mol% based on oxide. Glass composition.
The glass is expressed by mol% based on oxide, Bi 2 O 3 3 to 30%, B 2 O 3 10 to 50%, ZnO 0 to 45%, SiO 2 5 to 35%, BaO 0 to 20%, The glass composition for a phosphor-dispersed glass sheet according to claim 4 or 5, which contains MnO 2 0 to 1% and CeO 2 0 to 1%.
A phosphor-dispersed glass sheet produced by firing the glass composition for a phosphor-dispersed glass sheet according to any one of claims 1 to 6.
The phosphor-dispersed glass sheet according to claim 7, having a porosity of 5% or less.
The phosphor-dispersed glass sheet according to claim 7 or 8, wherein the total light transmittance is 70% or more.
The phosphor-dispersed glass sheet according to any one of claims 7 to 9, wherein the parallel light transmittance is 4% or more and the total light transmittance is 70% or more.
11. The phosphor-dispersed glass sheet according to claim 7, wherein the quantum conversion efficiency is 85% or more.