JP5939463B2 - Glass and wavelength conversion member using the glass - Google Patents

Description

  The present invention relates to glass used for a wavelength conversion member that is a constituent member of a light emitting device such as an LED (light emitting diode) or an LD (laser diode).

  In recent years, white LEDs have been increasingly applied to lighting applications as next-generation light sources that replace incandescent bulbs and fluorescent lamps. The white LED has a configuration in which, for example, a light emitting surface of an LED chip is molded with an organic binder resin containing phosphor powder. When excitation light emitted from the LED chip passes through the mold part, a part of the excitation light is absorbed by the phosphor powder and wavelength-converted, and the other excitation light is transmitted without being wavelength-converted. The light that has undergone wavelength conversion and the transmitted light that has not undergone wavelength conversion are combined to produce desired white light. However, there is a problem that the mold resin constituting the LED element is deteriorated by high-power, short-wavelength excitation light in the blue to ultraviolet region and easily causes discoloration.

  In order to solve the above problem, a phosphor powder is incorporated into a glass matrix by sintering a material containing a lead-free glass powder having a softening point of 500 ° C. or higher and a phosphor powder at a temperature higher than the softening point of the glass. Patent Document 1 proposes a wavelength conversion member in which the above is dispersed. Since the phosphor powder is dispersed in a glass matrix that is an inorganic material, the wavelength conversion member has an advantage that it is chemically stable and hardly deteriorated, and the member is not easily discolored by excitation light. However, some phosphor powders have low heat resistance, and when sintered together with a lead-free glass powder having a softening point of 500 ° C. or higher, the phosphor powder is thermally deteriorated and the luminous efficiency is lowered. There is a problem.

  Therefore, in order to suppress the thermal deterioration of the phosphor powder, a method of dispersing the phosphor powder in the low melting point glass has been proposed (for example, see Patent Documents 2 and 3).

JP 2003-258308 A JP 2008-19421 A JP 2005-11933 A

  The wavelength conversion members described in Patent Documents 2 and 3 still have a problem that discoloration is likely to occur due to the reaction between glass and phosphor powder during sintering. In addition, since the weather resistance of glass is low, there is also a problem that the surface of the wavelength conversion member is altered during use, particularly in a high humidity environment, the transmittance is lowered, and the light emission efficiency is greatly lowered.

  In view of the above, an object of the present invention is to provide a glass that is less likely to react with a phosphor powder, has excellent weather resistance, and can obtain a wavelength conversion member that is less deteriorated even when used over a long period of time. It is.

In the present invention, the glass composition is mol%, SnO 50 to 80%, P ₂ O ₅ 15 to 25% (however, 25% is not included), ZrO ₂ 0.3 to ₃ %, Al ₂ O ₃ 0 _{.1~10%, B 2 O 3 0~10} %, Li 2 O 0~10%, Na 2 O 0~10%, K 2 O 0~10%, Li 2 O + Na 2 O + K 2 O 0~10% MgO 0.1 to 10%, CaO 0 to 3%, SrO 0 to 2.5%, BaO 0 to 2%, MgO + CaO + SrO + BaO 0.1 to 10% and ZrO ₂ + Al ₂ O ₃ + MgO 0.5 to 10% _containing, relates to a glass which is a SnO _/ P 2 O 5 2.1~4.8.

In general, SnO—P ₂ O ₅ glass, which is a low-melting glass, has low weather resistance, and when it is mixed and sintered with phosphor powder, it reacts with the phosphor powder and its luminous efficiency tends to decrease. . On the other hand, the glass of the present invention is characterized by containing a predetermined amount of ZrO ₂ , Al ₂ O ₃ and MgO as essential components based on SnO—P ₂ O ₅ glass. Thereby, the glass of this invention can suppress reaction with fluorescent substance powder, and is excellent also in a weather resistance. Therefore, the wavelength conversion member formed by sintering the mixed powder containing the glass and the phosphor powder of the present invention is excellent in luminous efficiency and has a characteristic that it is less deteriorated even when used over a long period of time.

  Secondly, it is preferable that the glass of the present invention does not substantially contain ZnO.

  According to the said structure, generation | occurrence | production of devitrification at the time of baking can be suppressed.

Thirdly, it is preferable that the glass of the present invention does not substantially contain SiO ₂ .

  According to the said structure, the fall of the transmittance | permeability by phase-separation can be suppressed.

  In the present invention, “substantially does not contain” means that the corresponding components are not intentionally contained (specifically, less than 0.1 mol%) except for inevitable impurities.

  Fourth, the glass of the present invention preferably has a yield point of 400 ° C. or lower.

  According to the said structure, since the wavelength conversion material containing the glass of this invention and fluorescent substance powder can be sintered at low temperature, deterioration of fluorescent substance powder can be suppressed.

  Fifth, it is preferable that the glass of the present invention does not exhibit a crystallization peak temperature in a measurement curve obtained by differential thermal analysis.

  According to the said structure, devitrification becomes difficult to produce at the time of baking.

  Sixth, the present invention relates to a glass powder comprising any one of the above glasses.

  Seventh, the present invention relates to a wavelength conversion material containing the glass powder and the phosphor powder.

  Eighth, the present invention relates to a wavelength conversion member made of a sintered body of the wavelength conversion material.

  Ninthly, the present invention relates to a light emitting device comprising any one of the wavelength conversion members and a light source that irradiates the wavelength conversion member with excitation light of a phosphor powder.

  ADVANTAGE OF THE INVENTION According to this invention, the glass which can obtain the wavelength conversion member which is hard to react with fluorescent substance powder, is excellent in a weather resistance, and is hardly deteriorated even if used over a long period of time can be provided.

  Below, the reason which limited the composition of the glass of this invention as mentioned above is demonstrated. In the following description, “%” means “mol%” unless otherwise specified.

  SnO is a component that forms a glass skeleton and lowers the thermophysical temperature (glass transition point, yield point, softening point, etc.). The content is 50 to 80%, preferably 53 to 75%, more preferably 56 to 72%, and particularly preferably 58 to 68%. When there is too little content of SnO, it exists in the tendency for a thermophysical temperature to rise. As a result, it becomes difficult to sinter the wavelength conversion material containing the glass of the present invention at a low temperature, and the phosphor powder tends to deteriorate. On the other hand, when the content of SnO is too large, devitrification beads (especially tetravalent tin) due to Sn are precipitated in the glass at the time of melting and the transmittance tends to decrease, resulting in high luminous efficiency. It becomes difficult to obtain a wavelength conversion member having. Moreover, it becomes difficult to vitrify by melting and separating.

P ₂ O ₅ is a component that forms a glass skeleton. The content is 15 to 25% (however, 25% is not included), preferably 18 to 24%, more preferably 20 to 23%. When the content of P ₂ O ₅ is too small, it is difficult to vitrify. On the other hand, when the content of P ₂ O ₅ is too large, thermal properties temperature tends to increase. As a result, it becomes difficult to sinter the wavelength conversion material containing the glass of the present invention at a low temperature, and the phosphor powder tends to deteriorate. Further, the weather resistance tends to be remarkably lowered.

In order to lower the thermophysical temperature and stabilize the glass, the SnO / P ₂ O ₅ value (molar ratio) must be 1.6 to 4.8, preferably 1.8 to 4.8. It is preferable to adjust to the range of 3.8, more preferably 2.3 to 3.3. When the value of SnO / P ₂ O ₅ is too small, the thermophysical temperature tends to increase. As a result, it becomes difficult to sinter the wavelength conversion material containing the glass of the present invention at a low temperature, and the phosphor powder tends to deteriorate. Further, the weather resistance tends to be remarkably lowered. On the other hand, when the value of SnO / P ₂ O ₅ is too large, devitrification spots due to Sn are precipitated in the glass and the transmittance tends to decrease. As a result, a wavelength conversion member having high luminous efficiency is obtained. It becomes difficult to obtain.

ZrO ₂ is a component that improves weather resistance. The content is 0.3 to 3%, preferably 0.35 to 2, more preferably 0.4 to 1.5. When the content of ZrO ₂ is too small, the effect is difficult to obtain. On the other hand, when the content of ZrO ₂ is too large, turbid and devitrification or phase separation at the time of melting, the transmittance tends to decrease. As a result, the light emission efficiency of the wavelength conversion member using the glass of the present invention tends to decrease.

Al ₂ O ₃ is a component that improves the weather resistance and stabilizes the glass. Its content is 0.1 to 10%, preferably 0.1 to 7%, more preferably 1 to 5%. When the content of Al ₂ O ₃ is too small, the effect is difficult to obtain. When the content of Al ₂ O ₃ is too large, thermal properties temperature tends to increase. As a result, it becomes difficult to sinter the wavelength conversion material containing the glass of the present invention at a low temperature, and the phosphor powder tends to deteriorate.

B ₂ O ₃ is a component that stabilizes the glass and is also a component that suppresses the reaction with the phosphor powder. The content is 0 to 10%, preferably 0 to 5%, more preferably 0 to 3%. If the B ₂ O ₃ content is too large, thermal properties temperature tends to increase. As a result, it becomes difficult to sinter the wavelength conversion material containing the glass of the present invention at a low temperature, and the phosphor powder tends to deteriorate.

Li ₂ O is a component that significantly lowers the thermophysical temperature and improves the luminous efficiency of the wavelength conversion member. The content is 0 to 10%, preferably 0 to 7%, more preferably 1 to 5%. The content of Li 2 _O is too large, the glass becomes significantly instable difficult to vitrify.

Na ₂ O is a component that lowers the thermophysical temperature and slightly improves the luminous efficiency of the wavelength conversion member. The content is 0 to 10%, preferably 0 to 7%, more preferably 0 to 5%. When the content of Na 2 _O is too large, it is difficult to vitrify the glass becomes unstable.

K ₂ O is a component that slightly lowers the thermophysical temperature and improves the light emission efficiency of the wavelength conversion member. The content is 0 to 10%, preferably 0 to 7%, more preferably 1 to 5%. When the content of K 2 _O is too large, it is difficult to vitrify the glass becomes unstable.

_{Incidentally,} Li 2 O, 0% in total of Na ₂ O and _{K 2} O, further 0 to 7%, and particularly preferably 1 to 5%. When there is too much total amount of these components, glass will become unstable and it will become difficult to vitrify.

  MgO is a component that improves weather resistance. Moreover, there is an effect of remarkably improving the light emission efficiency of the wavelength conversion member. The content is 0.1 to 10%, preferably 0.3 to 7%, more preferably 0.5 to 3%. If the content of MgO is too small, the above effect is difficult to obtain. When there is too much content of MgO, it will devitrify at the time of baking and the transmittance | permeability will fall easily. As a result, it becomes difficult to obtain a wavelength conversion member having high luminous efficiency.

In the present invention, the total amount of ZrO ₂ , MgO and Al ₂ O ₃ is 0.5 to 11%, preferably 0.5 to 10%, more preferably 1 to 5%, still more preferably 2 to 2. 4%. When the total amount of these components is too small, it is difficult to obtain the effect of improving the weather resistance. When there is too much total amount of these components, it will devitrify at the time of baking and the transmittance | permeability will fall easily. As a result, it becomes difficult to obtain a wavelength conversion member having high luminous efficiency.

  CaO is a component that improves weather resistance. Its content is 0-3%, preferably 0-2.5%, more preferably 0-2%. When there is too much content of CaO, it will devitrify at the time of baking and the transmittance | permeability will fall easily. As a result, it becomes difficult to obtain a wavelength conversion member having high luminous efficiency.

  SrO is a component that improves weather resistance. The content is 0 to 2.5%, preferably 0 to 2%, more preferably 0 to 1.5%. When there is too much content of SrO, it will devitrify at the time of baking and the transmittance | permeability will fall easily. As a result, it becomes difficult to obtain a wavelength conversion member having high luminous efficiency.

  BaO is a component that improves the weather resistance. Its content is 0-2%, preferably 0-1.5%, more preferably 0-1%. When there is too much content of BaO, it will devitrify remarkably at the time of baking and it will become easy to reduce the transmittance | permeability. As a result, it becomes difficult to obtain a wavelength conversion member having high luminous efficiency.

  Note that the total amount of MgO, CaO, SrO and BaO is preferably 0.1 to 10%, more preferably 0.1 to 7%, and particularly preferably 1 to 5%. If the total amount of these components is too small, it is difficult to obtain the effect of improving the weather resistance. On the other hand, when there is too much total amount of these components, it will devitrify at the time of baking and the transmittance | permeability will fall easily. As a result, it becomes difficult to obtain a wavelength conversion member having high luminous efficiency.

  ZnO is a component that improves the weather resistance, but if it is contained in a small amount in the composition system of the present invention, it tends to devitrify during firing. Therefore, in the present invention, it is preferable that ZnO is not substantially contained.

When SiO ₂ is contained even in a small amount, the phase is separated and white turbid, and the transmittance tends to decrease. Therefore, in the present invention, it is preferred not to contain SiO ₂ substantially.

In addition to the above components, various components can be added as long as the effects of the present invention are not impaired. For example, in order to improve the weather resistance, Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ or La ₂ O ₃ may be contained up to 10% in total.

However, since coloring components such as Fe ₂ O ₃ , Cr ₂ O ₃ , CoO, CuO, and NiO reduce internal transmittance, it is preferable that these components are combined in an amount of 0.02% or less.

  The glass of the present invention preferably has an internal transmittance of 70% or more, further 80% or more, particularly 90% or more at a thickness of 1 mm and a wavelength of 588 nm. If the internal transmittance is too low, it becomes difficult to obtain a wavelength conversion member having high luminous efficiency.

In order to obtain a glass having a high internal transmittance, a glass raw material with few colored impurities such as iron, chromium, cobalt, copper and nickel is used, or the internal transmittance due to the precipitation of devitrification bumps caused by Sn. In order to suppress the decrease, it is preferable to melt in a reducing atmosphere (non-oxidizing atmosphere such as N ₂ gas or Ar gas) or to add a small amount of a reducing agent such as metallic aluminum to the glass raw material and melt it.

  The glass of the present invention preferably has a yield point of 400 ° C. or lower, more preferably 380 ° C. or lower. If the yield point is too high, it becomes difficult to sinter the wavelength conversion material containing the glass of the present invention at a low temperature, and the phosphor powder tends to deteriorate. Further, the weather resistance tends to be remarkably lowered.

  Furthermore, it is preferable that the glass of the present invention does not exhibit a crystallization peak temperature in a measurement curve obtained by differential thermal analysis. Thereby, the devitrification at the time of baking of the wavelength conversion material becomes difficult to occur.

  Next, the wavelength conversion member using the glass of this invention is demonstrated. The wavelength conversion member of the present invention comprises a sintered body of a wavelength conversion material including the glass powder of the present invention and a phosphor powder.

  The phosphor powder that can be used in the present invention is not particularly limited as long as it is generally available on the market. Examples thereof include phosphor powders made of at least one selected from oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, aluminate chlorides, and halophosphates. In addition, a phosphor powder made of an organic material may be used. Phosphor powders such as nitrides, oxynitrides, chlorides, acid chlorides, sulfides, oxysulfides, halides, chalcogenides, aluminates, and halophosphates are made into glass powders by heating during firing. To cause abnormal reactions such as foaming and discoloration, and the degree becomes more remarkable as the firing temperature is higher. Since the glass used in the present invention has a low softening point and can be sintered at a low temperature (for example, 400 ° C. or lower), the above-described phosphor powder that easily reacts with the glass powder can also be used.

  Among the phosphor powders, those having an excitation band at a wavelength of 300 to 500 nm and an emission peak at a wavelength of 380 to 780 nm, particularly blue (wavelength 440 to 480 nm), green (wavelength 500 to 540 nm), yellow (wavelength) It is preferable to use one that emits light in the range of 540 to 595 nm and red (wavelength of 600 to 700 nm).

(Sr, Ba) ₃ MgSi ₂ O ₈ : Eu ²⁺ is an example of the phosphor powder that emits blue light when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 to 440 nm.

The phosphor powder that emits green light when irradiated with ultraviolet to near-ultraviolet excitation light of wavelength ^{_{300~440nm, SrAl 2 O 4: Eu}} 2+ and the like.

Examples of the phosphor powder that emits green light when irradiated with blue excitation light having a wavelength of 440 to 480 nm include SrGa ₂ S ₄ : Eu ²⁺ .

Examples of the phosphor powder that emits yellow light when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 to 440 nm include ZnS: Eu ²⁺ .

As phosphor powder that emits yellow light when irradiated with blue excitation light having a wavelength of 440 to 480 nm, Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ²⁺ , SrBaSiO ₄ : Eu ²⁺ , La ₃ Si ₆ N ₁₁ : Ce ^{3+ and the} like.

Examples of the phosphor powder that emits red light when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 to 440 nm include CaS: Yb ²⁺ .

Examples of the phosphor powder that emits red light when irradiated with blue excitation light having a wavelength of 440 to 480 nm include (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ .

  A plurality of phosphor powders may be mixed and used in accordance with the wavelength range of excitation light or light emission. For example, when white light is obtained by irradiating excitation light in the ultraviolet region, phosphor powders that emit blue, green, yellow, and red fluorescence may be mixed and used.

  The luminous efficiency of the wavelength conversion member varies depending on the type and content of the phosphor powder dispersed in the glass matrix, the thickness of the wavelength conversion member, and the like. The phosphor powder content and the thickness of the wavelength conversion member may be adjusted so as to optimize the luminous efficiency. However, if the phosphor powder content is too high, sintering becomes difficult or the porosity is low. As a result, it becomes difficult to efficiently irradiate the phosphor powder with the excitation light, and the mechanical strength of the wavelength conversion member tends to decrease. On the other hand, if the content of the phosphor powder is too small, it becomes difficult to obtain sufficient light emission. Therefore, the content of the phosphor powder in the wavelength conversion material is preferably 0.01% to 60%, more preferably 0.05% to 55%, and particularly preferably 0.08% to 50% in mass%.

  The wavelength conversion material of the present invention may contain a light diffusing material such as silica or alumina as long as the effects of the present invention are not impaired.

  The wavelength conversion material may be fired in the air, but a dense sintered body can be easily obtained by firing in a reduced pressure or vacuum atmosphere or an inert gas atmosphere such as nitrogen or argon. It is preferable because the reaction between the glass powder and the phosphor powder can be suppressed.

  The firing temperature of the wavelength conversion material is preferably in the range of 300 to 400 ° C. If the firing temperature is too low, the porosity of the sintered body increases and the transmittance may decrease. On the other hand, when the firing temperature is too high, the phosphor powder may be deteriorated, or the glass powder and the phosphor powder may react to significantly reduce the light emission efficiency.

  The form of the wavelength conversion material of the present invention is not particularly limited, and examples thereof include powder, a pressure-molded body, a paste, and a green sheet.

  The pressure-molded body of the wavelength conversion material can be produced by adding 0 to 5% by mass of a resin binder to a mixed powder containing glass powder and phosphor powder, and pressure-molding with a mold. The pressure-molded body is heated at a temperature of, for example, 250 ° C. or less to remove the binder, and then fired at the firing temperature described above to obtain a wavelength conversion member.

  As the resin binder, a resin binder having a decomposition end temperature of 250 ° C. or lower is preferably used. For example, nitrocellulose, polyisobutyl acrylate, polyethyl carbonate, aliphatic polypropylene carbonate, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate And polyethyl methacrylate. These can be used alone or in admixture of two or more.

  The paste-form wavelength conversion material can be produced by adding a resin binder, a solvent, and the like to a mixed powder containing glass powder and phosphor powder and kneading them. The proportion of the mixed powder in the entire paste is generally 30 to 90% by mass.

  The resin binder is a component that increases the film strength after drying the paste and imparts flexibility to the film. As the resin binder, those described above can be used, and the content is generally about 0.1 to 20% by mass.

  The resin binder is preferably used after diluted in a solvent. As for content of a solvent, about 10-50 mass% is common. Examples of the solvent include terpineol, isoamyl acetate, toluene, methyl ethyl ketone, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3 pentadiol monoisobutyrate and the like.

  A wavelength conversion member can be produced using a paste-like wavelength conversion material as follows. First, an inorganic material base material having a thermal expansion coefficient similar to that of glass powder is prepared, and a paste-like wavelength conversion material is applied to the surface by a screen printing method, a batch coating method, or the like, and a coating layer having a predetermined film thickness And then dried. Subsequently, after firing at the firing temperature described above, the wavelength conversion member can be obtained by removing the inorganic material substrate.

  The wavelength conversion material in the form of a green sheet can be produced as follows. First, a resin binder, a plasticizer, a solvent, etc. are added and kneaded with respect to the mixed powder containing glass powder and fluorescent substance powder, and a slurry is obtained. The obtained slurry is formed into a sheet shape on a film of polyethylene terephthalate (PET) or the like by a doctor blade method. By drying the sheet molded body, the organic solvent and the like can be removed to obtain a green sheet. As for the ratio of the mixed powder which occupies in a green sheet, about 50-80 mass% is common.

  As the resin binder and the solvent, those described above can be used. The resin binder content is generally about 0.1 to 30% by mass, and the solvent content is generally about 1 to 40% by mass.

  The plasticizer is a component that controls the drying speed and imparts flexibility to the dried film, and the content thereof is generally about 0 to 10% by mass. Examples of the plasticizer include dibutyl phthalate, butyl benzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, and dibutyl phthalate, and these can be used alone or in combination.

  A wavelength conversion member can be produced as follows using a green sheet-like wavelength conversion material. First, an inorganic material base material having a thermal expansion coefficient comparable to that of glass powder is prepared, a green sheet is laminated on the surface, and thermocompression bonding is performed. Thereafter, the wavelength conversion member can be obtained by firing at the firing temperature described above and removing the inorganic material substrate.

  A light-emitting device can be obtained by combining the wavelength conversion member obtained as described above and a light source (for example, LED or LD) that emits excitation light of the phosphor powder to the wavelength conversion member.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

  Tables 1 and 2 show examples of the present invention (sample Nos. 1 to 12 and a to l), and Tables 3 and 4 show comparative examples (samples No. 13 to 20 and mt).

(1) Production and Evaluation of Glass First, raw materials were prepared so as to have the glass compositions shown in Tables 1 and 3, and mixed uniformly. Next, the prepared raw material was put into an alumina crucible and melted at 950 ° C. for 2 hours in an N ₂ atmosphere, and then a part of the glass melt was poured onto a carbon plate to be formed into a plate shape. Further, the remainder of the glass melt was formed into a film using a roller molding machine, pulverized with a coarse machine, and then passed through a 325 mesh sieve to obtain glass powder.

  About plate-like glass, after annealing, it cut | disconnected and grind | polished and measured the glass transition point and the yield point. Further, the surface condition after the weather resistance test was evaluated. The glass powder was measured for softening point, crystallization temperature, and internal transmittance. The results are shown in Tables 1 and 3.

(2) Production and Evaluation of Wavelength Conversion Member A phosphor powder was mixed with the obtained glass powder to obtain a mixed powder. In the phosphor powder column in Tables 2 and 4, “A” indicates Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ²⁺ , and “B” indicates (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ . . Moreover, content of the fluorescent substance powder in mixed powder was 3 mass%.

  The mixed powder was put into a mold and pressure-molded to produce a pressure-molded body having a size of 15 mm × 15 mm and a thickness of 5 mm. The pressure-molded body was sintered at a firing temperature shown in the table under a reduced pressure atmosphere of 100 Pa, and then processed to obtain a wavelength conversion member having a size of 10 mm × 10 mm and a thickness of 1 mm. About the obtained wavelength conversion member, the luminous efficiency before and behind a weather resistance test and the surface state after a weather resistance test were evaluated. The results are shown in Tables 2 and 4.

(3) Measurement and evaluation method of each characteristic The glass transition point and the yield point were measured using a thermomechanical analyzer (Thermo plus TMA8310: manufactured by Rigaku Corporation).

  The softening point and the crystallization temperature were measured using a DTA (Differential Thermal Analysis) apparatus (TAS-100: manufactured by Rigaku Corporation).

  The internal transmittance was determined as follows. A sintered body obtained by firing the glass powder at the sintering temperatures shown in Tables 1 and 3 was subjected to optical polishing processing so that the thickness became 1 mm to prepare a sample. For the obtained sample, the transmittance and reflectance at a wavelength of 588 nm were measured using a spectrophotometer, and the internal transmittance (the reflectance on both sides of the sample was added to the transmittance from the measured value of the transmittance and reflectance). Value).

  The weather resistance was evaluated by using a pressure cooker tester, allowing the sample to stand for 24 hours under conditions of an atmospheric pressure of 2 atm, a humidity of 95%, and a temperature of 121 ° C., and visually and microscopically checking for the presence of white turbidity on the sample surface. This was done by observation (PCT test). “◎” indicates that no microcracks or white turbidity due to elution of glass components, etc. was observed by visual observation and observation by a microscope, and “○” indicates that white turbidity was not observed by visual observation but was observed by a microscope. In addition, the case where cloudiness was observed visually and under a microscope was evaluated as “x”.

  Luminous efficiency was determined as follows. First, a sample was placed on a blue LED (wavelength 465 nm) lit at a current of 20 mA, and an energy distribution spectrum of light emitted from the upper surface of the member was measured in an integrating sphere. Next, the total luminous flux was calculated by multiplying the obtained spectrum by the standard relative luminous sensitivity, and the luminous efficiency was calculated by dividing the obtained total luminous flux by the power of the light source (0.072 W).

(4) Consideration of measurement and evaluation results As is clear from the table, sample No. Glasses 1 to 12 had low thermophysical temperatures (glass transition point 294 to 333 ° C., yield point 314 to 354 ° C., softening point 352 to 393 ° C.), and could be sintered at a low temperature of 366 to 399 ° C. Further, the crystallization peak temperature was not expressed. Furthermore, the internal transmittance was as high as 83% or more. Sample No. The glass of 1-12 and the wavelength conversion member of a-1 produced using these glasses did not change in the surface state after a weather resistance test. Moreover, the luminous efficiency of the wavelength conversion member was high, and almost no change in the luminous efficiency before and after the weather resistance test was confirmed.

  On the other hand, sample No. which is a comparative example. The surfaces of 13, 15 and 16 became cloudy after the weather resistance test. Moreover, the wavelength conversion member produced using these glasses showed a luminous efficiency of 10 to 12 lm / W before the weather resistance test, but the luminous efficiency significantly decreased to 2 to 3 lm / W after the weather resistance test. . No. No. 14 glass could not be evaluated because melt separation occurred during melting and it did not vitrify. No. Since the glass of 17 was phase-separated, it became cloudy and the internal transmittance was as low as 68%. No. The 18-20 glass had strong crystallinity and was devitrified during firing, so the internal transmittance was as low as 55-59%. Therefore, no. The wavelength conversion member produced using 17-20 glass had a low luminous efficiency of 4-6 lm / W.

Claims (6)

As a glass composition, in mol%, SnO 50 to 72 (provided that the excluded if it is 72% or _{more)%, P 2 O 5 15~25} % ( however, not including _25%), ZrO 2 0.3~ _{3%, Al 2 O 3 0.1~10} %, B 2 O 3 0~10%, Li 2 O 0~10%, Na 2 O 0~10%, K 2 O 0~10%, Li 2 O + Na ₂ O + K ₂ O 0-10%, MgO 0.1-10%, CaO 0-3%, SrO 0-2.5%, BaO 0-2%, MgO + CaO + SrO + BaO 0.1-11% and ZrO ₂ + Al ₂ O ₃ + containing 0.5 to 10% MgO, it contains substantially no SiO _2, comprising glass powder and a phosphor powder composed of _SnO / _P 2 O 5 _1.6~4.8 der Ruga Las A wavelength conversion material characterized by that . The wavelength conversion material according to claim 1, wherein the glass does not substantially contain ZnO. Wavelength conversion material according to claim 1 or 2 yield point of the glass is characterized in that at 400 ° C. or less. The wavelength conversion material according to any one of claims 1 to 3 , wherein the glass does not exhibit a crystallization peak temperature in a measurement curve obtained by differential thermal analysis. The wavelength conversion member which consists of a sintered compact of the wavelength conversion material as described in any one of Claims 1-4 . A light-emitting device comprising: the wavelength conversion member according to claim 5; and a light source that irradiates the wavelength conversion member with excitation light of phosphor powder.