JP2015046579A - Method for manufacturing optical conversion member, optical conversion member, illumination light source, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an optical conversion member which makes possible to simplify a process for manufacturing an optical conversion member, to reduce the time and labor, and the cost, and to effectively prevent the deactivation of a phosphor in manufacturing an optical conversion member; and a method for manufacturing such an optical conversion member.SOLUTION: A method for manufacturing an optical conversion member comprises: a kneading step in which glass powder, phosphor particles and a nano filler having a 50%-particle diameter Dof 50 nm or less are kneaded into a kneaded mixture; and a baking step in which the resultant kneaded mixture is shaped into a desired form and then baked. The optical conversion member comprises: glass; phosphor particles dispersed in the glass; and nano filler having a 50%-particle diameter of 50 nm or less and adsorbed onto the surfaces of the phosphor particles at an adsorption rate of 20-80%.

Description

  The present invention relates to a method for producing a light conversion member for converting the color of a light source, a light conversion member obtained by the production method, an illumination light source having the light conversion member, and a liquid crystal display device.

  The white LED is used as a white illumination light source with a minute electric power, and is expected to be applied to illumination applications. In general, the white light of a white LED is light of yellow, green, red, etc., which is a blue light emitted from a blue LED element serving as a light source and a color (wavelength) of a part of the blue light converted by a phosphor. And is obtained by synthesizing

  As a light conversion member for converting the color (wavelength) of light of such a light source, a member in which an inorganic phosphor is dispersed in glass is known (for example, see Patent Document 1). The light conversion member having such a configuration can utilize the high transmittance of glass, and can efficiently release the heat generated from the LED element to the outside of the light conversion member. Moreover, the damage of the light conversion member (especially phosphor) by light and heat is low, and long-term reliability is obtained.

  However, when manufacturing this light conversion member, if the phosphor particles and the glass material are mixed as they are as in Patent Document 1, there is a possibility that the phosphors may be deactivated by their interaction. In this case, the light conversion efficiency is lowered. In order to suppress such deterioration of product characteristics, a method of coating phosphor particles with ceramic fine particles (see Patent Document 2), a method of forming a metal oxide film (see Patent Documents 3 to 4), Etc. are known.

  Further, although not intended to cover the surface of the phosphor particles, as a phosphor-containing composition used for manufacturing a light emitting device, in order to improve the thixotropy, silica fine particles, Al, Zr and A phosphor-containing composition containing a metal oxide containing at least one metal selected from Ti and a light-emitting device formed using the same are known (see Patent Document 5).

JP 2003-258308 A JP 2012-229289 A Japanese Patent No. 4971630 JP 2007-169252 A JP 2008-260930 A

  However, as described in Patent Document 2, after making phosphor particles and ceramic fine particles into a slurry, drying is performed to remove the solvent, and heat treatment is performed to form a coating layer of ceramic fine particles. As described, in order to coat the phosphor particles with the oxide film, it is necessary to perform the film forming step independently and to isolate the coated phosphor particles once. Therefore, in order to manufacture the light conversion member, the manufacturing process of the light conversion member is performed completely independently of the formation of the phosphor particles, so that the manufacturing process is troublesome and the cost is excessive. .

  Moreover, although the thing of patent document 5 prevents sedimentation of a fluorescent substance particle and improves workability | operativity at the time of manufacture, a nanoparticle is made to adsorb | suck to the surface of a fluorescent substance particle, and, thereby, a fluorescent substance's There is no description or suggestion on the point of suppressing deactivation.

  Therefore, in view of the above problems, the present invention provides a light conversion member that can simplify the manufacturing process of the light conversion member, reduce labor and cost, and can effectively prevent phosphor deactivation during the production of the light conversion member. An object is to provide a manufacturing method and a light conversion member manufactured by the method.

  As a result of intensive studies by the present inventors, it is possible to suppress the deactivation of the phosphor by using a kneaded material kneaded with a predetermined nanofiller in the production of the light conversion member, and to maintain the luminescence conversion efficiency at a high rate. As a result, the present invention has been completed.

That is, the method for producing a light conversion member of the present invention includes a kneading step of kneading glass powder, phosphor particles, and a nano filler having a 50% particle size D50 of ₅₀ nm or less to obtain a kneaded product, and the obtained kneaded product. And a firing step of forming and firing in a desired shape.

  The light conversion member of the present invention is a light conversion member made of glass containing dispersed phosphor particles, and a nanofiller having a 50% particle size of 50 nm or less is adsorbed on the surface of the phosphor particles. The adsorption rate is 20 to 80%. Here, the adsorption rate of 20 to 80% means that the area of the portion where the nanofiller is adsorbed on the surface of the phosphor particles is 20 to 80%.

Moreover, 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 this light conversion member, It is characterized by the above-mentioned.
The liquid crystal display device of the present invention is a liquid crystal display device comprising a liquid crystal display panel and a backlight for illuminating the liquid crystal display panel, wherein the light conversion member of the present invention and the light are used as the backlight. It has the illumination light source which consists of a light source which can irradiate light outside through a conversion member.

  The method for producing a light conversion member of the present invention is a simple operation, but can reduce the interaction between the glass and the phosphor particles, and can effectively suppress the deactivation of the phosphor. And cost reduction.

  The light conversion member of the present invention can effectively prevent the phosphor from being deactivated as described above, and the light conversion efficiency of the light conversion member can be improved. Therefore, the characteristics of the light conversion member can be stabilized and efficiently manufactured.

  Since the light source illumination of the present invention uses the light conversion member of the present invention, stable illumination light with good light emission conversion efficiency can be obtained. Since the illumination light source is applied to the liquid crystal display device of the present invention, luminescence conversion efficiency is good, low power consumption can be expected, color reproducibility is high, and high-definition expression is possible.

  Hereinafter, the manufacturing method of the light conversion member, light conversion member, illumination light source, and liquid crystal display device of the present invention will be described in detail.

(First embodiment)
<Method for producing light conversion member>
The light conversion member of the present embodiment is composed of a sintered body of a mixed powder of glass powder, phosphor particles and nanofiller, and more specifically, a kneaded product obtained by kneading the mixed powder, a resin and an organic solvent. It consists of a sintered body obtained by firing. This light conversion member is preferably composed of a glass sheet obtained by applying a green sheet obtained by applying the kneaded material to a resin and drying it. 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 this light conversion member as a sintered body, a kneading step of kneading glass powder, phosphor particles, nanofiller, resin and organic solvent to obtain a kneaded product, What is necessary is just to perform sequentially the baking process which shape | molds in a desired shape and bakes and makes it a light conversion member. In explaining this manufacturing method, first, materials to be used will be explained.

[Material of light conversion member]
(Glass powder)
If the glass powder used here is a well-known thing conventionally used as a light conversion member, it can be used without being specifically limited. Moreover, it is preferable that the glass transition point Tg (henceforth only "Tg") is 300-550 degreeC. When the glass transition point exceeds 550 ° C., the temperature during firing during the manufacturing process of the light conversion member becomes high, and the glass and the phosphor may react to reduce the quantum conversion yield of the light conversion member. In order to suppress a decrease in quantum conversion yield, the Tg of the glass is preferably 520 ° C. or less, more preferably 500 ° C. or less, and further preferably 480 ° C. or less.

  On the other hand, if the glass transition point Tg is less than 300 ° C., the firing temperature is low, and the deashing temperature is higher than the temperature at which the glass flows, so the carbon content in the light conversion member increases, The quantum conversion yield may be reduced. In addition, the 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 340 ° C. or higher, and further preferably 380 ° C. or higher. In this specification, Tg of glass is calculated from a DTA curve.

The glass composition used here preferably has a Bi ₂ O ₃ —B ₂ O ₃ —ZnO system as a main component. Among them, it contains 5 to 35% of Bi ₂ O ₃ , 10 to 50% of B ₂ O _{3 and} 10 to 48% of ZnO in terms of mol% based on oxide, and the total amount of Bi ₂ O ₃ and ZnO is 15 % Or more and less than 70% is more preferable.

_{Further, Bi 2 O 3 8~35%,} B 2 O 3 10~45%, 15~45% ZnO, more preferably glass containing.

  This glass preferably consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. Hereinafter, each component of this glass is demonstrated.

Bi ₂ O ₃ is a component that lowers Tg and raises the refractive index without lowering the chemical durability of the glass. The content of Bi ₂ O ₃ is preferably 5 to 35%. If Bi ₂ O ₃ is less than 5%, the Tg of the glass powder increases, which is not preferable. More preferably, it is 8% or more. On the other hand, if it exceeds 35%, the glass becomes unstable and tends to be crystallized, which may impair the sinterability. In addition, the absorption edge of the glass shifts to the long wavelength side and absorbs the blue light of the LED element. Also, the refractive index becomes too high and the difference in refractive index from the phosphor increases, so that the luminous efficiency of the LED is increased. May be lowered. The content of Bi ₂ O ₃ is more preferably 8 to 35%, further preferably 10 to 35%.

B ₂ O ₃ is a glass network former and is a component capable of stabilizing the glass. 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 10 to 45%, further preferably 15 to 45%.

  ZnO is a component that lowers Tg and raises the refractive index. The content of ZnO is preferably 10 to 48%. If the ZnO content exceeds 48%, it will be difficult to vitrify, and it will be difficult to produce glass. The content of ZnO is more preferably 15 to 48%, further preferably 15 to 45%.

SiO ₂ is a component that increases the stability of the glass. The content of SiO ₂ is preferably 0 to 35%. If the content of SiO ₂ exceeds 35%, Tg may be high. The content of SiO ₂ is more preferably 0 to 30%, further preferably 0 to 20%.

TeO ₂ is a component that lowers Tg, raises the refractive index, and lowers the liquidus temperature. The content of TeO ₂ is preferably 0 to 20%. If the TeO ₂ content exceeds 20%, the sinterability may be impaired, or the phosphor may be deactivated by reacting with the phosphor during firing. The TeO ₂ content is more preferably 16% or less, further preferably 14% or less, and particularly preferably 12% or less.

Al ₂ O ₃ is a component that improves chemical durability and suppresses reaction with the phosphor during firing. The content of Al ₂ O ₃ is preferably 0 to 4%. If the content of Al ₂ O ₃ exceeds 4%, Tg may become too high, the liquidus temperature may be increased, and the sinterability may be impaired. The content of Al ₂ O ₃ is more preferably 3% or less.

  CaO, SrO, MgO, and BaO alkaline earth metal oxides are components that increase the stability of glass and lower Tg. The total amount of alkaline earth metal oxide is preferably 0 to 20%. If this 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.

Since MnO ₂ and CeO ₂ function as an oxidizing agent in the glass, it is preferable to contain them. 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. Therefore, the content of MnO ₂ and CeO ₂ is preferably 0 to 1%. If the content exceeds 1%, coloring may increase. Preferably it is 0 to 0.5%.

The alkali metal oxides of Li ₂ O, Na ₂ O and K ₂ O are components that lower Tg. The total amount of alkali metal oxides is preferably 0 to 15%. If the total amount exceeds 15%, the refractive index is lowered, and the chemical durability of the glass may be lowered. More preferably, it is 0-10%, More preferably, it is 0-5%.

  The glass may further include a glass that can degas 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. The content of these components is preferably 0 to 15%.

The density of the glass is preferably 3.5 to 7.0 g / cm ³ . Outside this range, the difference in specific gravity with the phosphor becomes large, and the phosphor particles are not uniformly dispersed in the glass powder, and conversion efficiency may be reduced when a light conversion member is used. The density is more preferably 3.7 to 6.5 g / cm ³ , and still more preferably 4.1 to 6.0 g / cm ³ .

  The refractive index of the glass is preferably 1.70 to 2.20 at a wavelength of 633 nm. If it is out of this range, the difference in refractive index from the phosphor particles becomes large, and there is a possibility that the conversion efficiency is lowered when the light conversion member is used. The refractive index is more preferably 1.70 to 2.10, still more preferably 1.75 to 2.10.

  The glass having the above composition and characteristics is used as a raw material in powder form. 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.

  At this time, the 50% particle size of the glass powder is preferably less than 2.0 μm. When the 50% particle size is 2.0 μm or more, the phosphor particles are not uniformly dispersed in the glass powder, and the light conversion efficiency decreases when the light conversion member is used, and the amount of shrinkage during firing increases. There is a fear. The 50% particle size is more preferably 1.5 μm or less, and even more preferably 1.4 μm or less.

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 are difficult to be uniformly dispersed in the glass powder, and when a light conversion member is produced, the light conversion efficiency of the phosphor is reduced, or the amount of shrinkage during firing May increase. D _max is more preferably 20 μm or less, and still more preferably 15 μm or less.

In the present specification, the 50% particle size is a value (D ₅₀ ) calculated as a 50% value in cumulative% on a volume basis from the particle size distribution obtained by laser diffraction particle size distribution measurement. The diameter _Dmax is a value of the maximum particle diameter calculated by laser diffraction particle size distribution measurement.

(Phosphor particles)
The phosphor particles used here are not limited as long as they can convert the wavelength of the light source, and may be any known phosphor particles used for the light conversion member. Examples of such phosphor particles include oxides, nitrides, oxynitrides, sulfides, oxysulfides, halides, aluminate chlorides, halophosphates, and the like. 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.

As long as the light passing through the light conversion member is converted into a desired color, the phosphor only needs to contain one or more compounds selected from the group consisting of the above-mentioned compounds, and a plurality of types of compounds are mixed. May be 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. From the viewpoint of increasing the quantum conversion yield, the phosphor is preferably an oxide or aluminate chloride. The phosphor of oxide or aluminate chloride is more preferably a garnet crystal. The garnet crystal is excellent in water resistance and heat resistance, and when going through the manufacturing process described later, it is difficult for deactivation in the slurry and deactivation during firing. Examples of the garnet-based crystal include a composite oxide of yttrium and aluminum (Y ₃ Al ₅ O ₁₂ ; hereinafter abbreviated as YAG in this specification), a composite oxide of lutetium and aluminum (Lu ₃ Al ₅ O ₁₂ ; Hereinafter, it is abbreviated as LAG in this specification.

In addition, when a red component is included in the synthesized light, a phosphor made of CASN crystal such as (Ca (Sr) AlSiN ₃ ) or SiAlON crystal is included as a phosphor capable of converting blue light into red. Is preferred.

The 50% particle diameter D ₅₀ of the phosphor particles is preferably 1 to 30 μm. If the 50% particle diameter 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, or the phosphor particles are likely to aggregate with each other, and the light conversion efficiency May decrease. The 50% particle size is more preferably 3 μm or more, further preferably 5 μm or more, and particularly preferably 7 μm or more. On the other hand, if the 50% particle size of the phosphor particles is more than 30 μm, the dispersibility in the light conversion member is deteriorated, the light conversion efficiency is lowered, and chromaticity unevenness may occur. Therefore, the 50% particle size is more preferably 20 μm or less, and even more preferably 15 μm or less.

(Nano filler)
The nanofiller used here is fine inorganic particles having a 50% particle size of 50 nm or less. By using such a nanofiller, the nanofiller is adsorbed on the surface of the phosphor particles in the manufacturing process of the light conversion member, and the phosphor is deactivated by the interaction between the phosphor particles and the glass material. To suppress. If the 50% particle size of the nanofiller exceeds 50 nm, the light transmittance may be adversely affected. Further, the lower limit is not particularly limited, but is preferably 2 nm or more because it tends to aggregate when it is too small, and secondary particles are present in the light conversion member, which may adversely affect the light transmittance.

  As this nanofiller, those having heat resistance to the firing temperature at the time of production of the light conversion member and being easily adsorbed to the phosphor are preferable, and examples thereof include silica, alumina, titania, zirconia, magnesia and the like. Of these, at least one or more may be contained.

(Resin and organic solvent)
As the resin used here, ethyl cellulose, nitrocellulose, acrylic resin, vinyl acetate, butyral resin, melamine resin, alkyd resin, rosin resin, or the like can be used. As the organic solvent, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols, ethers, ketones or esters 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.

Next, each process in the manufacturing method of the light conversion member of this embodiment is demonstrated.
[Kneading process]
The kneading step in the present embodiment involves kneading the above glass powder, phosphor particles, nanofiller, resin and organic solvent into a slurry-like kneaded material, as long as these raw materials can be uniformly kneaded. 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 this kneading, the nanofiller may be adsorbed to a predetermined amount on the surface of the phosphor particles, and the kneading method is not limited. That is, the glass powder, the phosphor particles and the nanofiller may all be kneaded at the same time, or the primary kneading step of kneading the phosphor particles and the nanofiller is performed first, and then the secondary kneading is performed by adding the glass powder and kneading. You may make it perform a process.
A kneading method in which primary kneading and secondary kneading are sequentially performed in two stages is preferable in that the nanofiller can be effectively adsorbed on the surface of the phosphor particles. In this case, in the primary kneading, it is preferable to knead the phosphor particles and nanofillers by adding a solvent. Further, the vehicle may be added by primary kneading or secondary kneading.

  When kneading the above components, when the total amount of the phosphor particles, nanofiller and glass powder is 100%, the content of each component in the mixed powder is the volume fraction, and the phosphor particles are 1 to 40%. The nano filler is preferably 0.6 to 6.5%, and the glass powder is preferably 53.5 to 98.4%.

  If phosphor particles are contained at 1% or more and glass powder at 98.4% or less, the quantum conversion yield can be increased, incident light can be efficiently converted, and light of a desired color can be obtained. The volume fraction of the phosphor particles is more preferably 5% or more, further preferably 7% or more, and particularly preferably 10% or more. The volume fraction of the glass powder is more preferably 91% or less, further preferably 87% or less, and particularly preferably 83% or less.

  When the volume fraction of the phosphor particles is more than 40% and the volume fraction of the glass powder is less than 53.5%, the sinterability of the mixture of the phosphor particles and the glass powder is impaired, and the transmittance of the light conversion member is further reduced. May be low. Moreover, there is a possibility that light of a desired color cannot be obtained due to an increase in converted fluorescent light. The volume fraction of the phosphor particles is more preferably 35% or less, still more preferably 30% or less, and particularly preferably 25% or less. The volume fraction of the glass powder is more preferably 55% or more, further preferably 60% or more, and particularly preferably 65% or more.

  Moreover, it is preferable that the volume fraction of the nanofiller is 0.6% or more because the interaction of the phosphor particles with the glass can be effectively suppressed and the deactivation of the phosphor can be suppressed. The volume fraction of the nanofiller is more preferably 0.8% or more, further preferably 1.0% or more, and particularly preferably 1.2% or more. Moreover, when the volume fraction of the nanofiller exceeds 6.5%, in addition to being present on the surface of the phosphor particles, the amount of the nanofiller dispersed in the glass is increased, and an aggregate of nanofillers is generated. It becomes easy, and there exists a possibility that the transmittance | permeability of a light conversion member may fall. The volume fraction of the nanofiller is preferably 6.0% or less, more preferably 5.5% or less, still more preferably 5.0% or less, and particularly preferably 4.5% or less.

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

[Baking process]
The firing step in the present invention involves firing the kneaded product obtained in the kneading step into a desired shape and then firing. First, 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 nanofiller are kneaded in a vehicle and defoamed to obtain a slurry-like kneaded product. The obtained kneaded material is coated on a resin by a doctor blade method and dried. After drying, the sheet is cut into a desired size and the transparent resin is peeled off to obtain a sheet-like kneaded product. This is also called a green sheet. Furthermore, by pressing these to form a laminate, a molded body having a desired thickness can be secured.

  Here, the resin for applying the slurry-like kneaded material is not particularly limited as long as it has releasability. Moreover, it is preferable that it is transparent from the viewpoint of ease of inspection. Furthermore, it is preferable that the thickness is uniform so that a green sheet having a uniform thickness can be obtained, and examples thereof include a film-like transparent resin such as a PET film.

  Next, the obtained kneaded product is fired. This firing is to sinter the mixed powder to obtain glass containing dispersed phosphor particles formed by adsorbing nanofillers on the surface. What is necessary is just to manufacture a glass body with a well-known baking method.

  As long as the firing step can be performed to form a glass body, the conditions are not particularly limited, but the firing temperature is preferably in the range of 400 to 650 ° C., and the firing time is preferably in the range of 1 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 conversion yield of a light conversion member may fall.

  The light conversion member thus obtained has phosphor particles dispersed in glass, and nanofillers are adsorbed on the surfaces of the phosphor particles, and the nanofillers are phosphors due to interaction with glass. It can be obtained as a stable characteristic in which the deactivation is suppressed. Note that it is not always necessary that all of the nanofillers are adsorbed on the surface of the phosphor particles, and some of them may be dispersed in the glass.

  In addition, the light conversion member having such excellent characteristics can be achieved only by a very simple operation of mixing raw materials without going through the step of coating the surface of the phosphor particles as in the prior art. Since the mixing operation of the raw materials can be used as it is with the equipment used in the conventional light conversion member, the light conversion member manufacturing method of the present invention can manufacture the light conversion member at low cost with an easy and simple operation. It is a very good invention that is possible.

<Light conversion member>
Next, the light conversion member of this embodiment will be described. This light conversion member is obtained by the production method described above, and is made of glass containing phosphor particles dispersed therein. Further, nanofillers are adsorbed on the surfaces of the phosphor particles dispersed in the glass. It will be. Such a light conversion member transmits a part of the light emitted from the light source, converts the wavelength of the remaining light, and synthesizes the transmitted light and the light having the converted wavelength, thereby obtaining a desired chromaticity. Can be irradiated to the outside. This light conversion member is particularly useful as a light conversion member for converting a blue light source into white. Moreover, as a light source used here, an LED light emitting element is preferable.

  Here, the light conversion member of the present embodiment is formed by dispersing phosphor particles having nanofillers adsorbed on the surface thereof in glass as described above, but a part of the nanofillers is phosphor particles. Partly dispersed in the glass. At this time, the adsorption rate of the nanofiller adsorbed on the surface of the phosphor particles is preferably 20 to 80%. If it is less than 20%, the amount of adsorption is small, and the phosphor may be deactivated by interaction with glass. More preferably, it is 25% or more, and more preferably 30% or more. If it exceeds 80%, the amount of nanofiller to be used increases, the amount of nanofiller dispersed in the glass increases, and the light transmittance of the light conversion member may be reduced. More preferably, it is 75% or less, More preferably, it is 70% or less.

  In addition, in this specification, the adsorption rate of the nano filler on the phosphor surface is the ratio of the length of the adsorbed portion of the nano filler to the circumference of the phosphor / glass interface in the SEM photograph of the fractured surface of the light conversion member. Is calculated as an average value of the above ratios of at least three or more sampled phosphor particles. At this time, the particle diameter of the phosphor particles in the section is calculated as (major axis + minor axis) / 2, and the particle diameter is within ± 10% of the 50% particle diameter of the phosphor particles used. A cross section is selected, and the circumference of the phosphor / glass interface is calculated by image processing. In addition, the length of the adsorption part of the nanofiller exists on the periphery of the phosphor / glass interface (on the SEM photograph, it overlaps with the phosphor / glass interface and hides the interface) and adsorbs the nanofiller. And the location of the adsorbed nanofiller is selected, and the length of the adsorbed portion is overlapped with the phosphor / glass interface by image processing as well as the circumference of the phosphor / glass interface. Length).

  The quantum conversion yield of this light conversion member is preferably 80% or more. If the quantum conversion yield is less than 80%, the thickness of the light conversion member must be increased in order to obtain a desired color. When the thickness is increased, the transmittance of the light conversion member may be reduced. The quantum conversion yield of the light conversion member is more preferably 85% or more, and still more preferably 90% or more. The quantum conversion 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.

  Since this light conversion member can maintain a high quantum conversion yield, even if the light conversion member is thinned, the above-described function of the light conversion member can be exhibited. The thickness of the light conversion member is preferably 50 to 500 μm. When the thickness of the light conversion member is 50 μm or more, handling of the light conversion member becomes easy, 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. If the thickness of the light conversion member is 500 μm or less, the total light flux transmitted through the light conversion member can be maintained high. The thickness of the light conversion member is preferably 400 μm or less, more preferably 300 μm or less, and particularly preferably 250 μm or less.

  If the phosphor to be used is extremely expensive, the amount of the phosphor to be contained in the light conversion member is to be suppressed as much as possible. Therefore, even if the total amount of light flux is sacrificed, the thickness of the light conversion member can be increased to ensure the light conversion efficiency. In such a case, the thickness of the light conversion member may be selected between 250 and 500 μm by balancing the total luminous flux and the light conversion efficiency.

  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 conversion 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.

(Second Embodiment)
A second embodiment of the present invention will be described below. This second embodiment has the same configuration as that of the first embodiment except that a heat resistant filler is further added to and mixed with glass powder, phosphor particles and nanofillers as powder raw materials. Only this difference will be described below.

The heat-resistant filler used here is a heat-resistant filler having a relational expression [D ₅₀ / n] of 2 to 20 between the 50% particle diameter D ₅₀ and the refractive index n at a wavelength of 633 nm. By including such a heat-resistant filler in the glass, when the light conversion member is produced, shrinkage that occurs during firing can be suppressed, and the uniform dispersibility of the phosphor particles in the light conversion member can be favorably maintained. If the relational expression [D ₅₀ / n] in this heat-resistant filler is less than 2, the light from the light source tends to be scattered, and the light transmittance of the light conversion member tends to decrease. The dispersibility of the resin may decrease, and shrinkage may not be suppressed uniformly. This relational expression [D ₅₀ / n] is preferably in the range of 3 to 18, more preferably 4 to 15.

The heat 50% particle diameter _{D 50} of the filler is 5~30μm is preferred. If it is less than 5 μm, light from the light source tends to be scattered and the light transmittance of the light conversion member may be reduced. If it exceeds 30 μm, the dispersibility of the heat-resistant filler in the light conversion member is reduced, and shrinkage during firing is caused. May not be sufficiently suppressed. The 50% particle size D ₅₀ is more preferably 6 to 25 μm, still more preferably 8 to 22 μm.

  Further, the refractive index n of the heat resistant filler at a wavelength of 633 nm is preferably 1.5 to 2.5. If the refractive index is out of the range, the difference in refractive index from the glass increases, so that the refraction at the interface between the heat-resistant filler and the glass increases and the light from the light source is easily scattered, and the light transmittance of the light conversion member is increased. May decrease. The refractive index n of the heat resistant filler is more preferably 1.6 to 2.3, and still more preferably 1.7 to 2.2.

  Moreover, this heat-resistant filler should just have heat resistance with respect to the calcination temperature at the time of manufacture of a light conversion member, for example, an alumina, a zirconia, magnesia etc. are mentioned, Among these, at least 1 type or more is contained. If you do.

  In addition, the refractive index of the heat-resistant filler was measured using a bulk body, and the refractive index n for light having a wavelength of 633 nm was measured using a model 2010 prism coupler manufactured by Metricon.

  As described above, the light conversion member in the second embodiment is configured by dispersing phosphor particles adsorbed with nanofillers and heat-resistant filler in glass. In order to sufficiently suppress shrinkage at the time of firing the light conversion member, when the total amount of glass, phosphor particles, nanofiller and heat-resistant filler is 100%, the volume fraction contains 3 to 30% heat-resistant filler. It is preferable to do. If the content is less than 3%, the shrinkage may not be sufficiently suppressed, and if it exceeds 30%, the light transmittance of the light conversion member may be reduced, and the utilization efficiency of the light source may be reduced.

  At this time, it is preferable that the glass contains 53.5 to 95.4%, phosphor particles 1 to 40%, and nanofiller 0.6 to 6.5% in terms of volume fraction. With such a content, the light conversion member can be manufactured in a well-balanced manner with the light transmittance from the light source and the light conversion amount of the phosphor particles. It is possible to suppress the occurrence of chromaticity unevenness.

  And manufacture of the light conversion member in the case of using this heat-resistant filler may be used by mixing with other powder raw materials in the kneading step. In addition, the powder raw materials may be mixed at the same time, or in the case of stepwise kneading such as primary kneading and secondary kneading, a heat-resistant filler may be added in at least one of the kneading steps. That's fine.

<Light source>
The illumination light source of the present invention includes the above-described 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.

<Liquid crystal display device>
Furthermore, a case where a liquid crystal display device is configured by combining the above-described light conversion member with a light source will be described. That is, the liquid crystal display device in the present embodiment is a liquid crystal display device including a liquid crystal display panel and a backlight that illuminates the liquid crystal display panel, and the light conversion member and the light conversion member are used as a backlight. And an illumination light source comprising a light source capable of irradiating light to the outside.

(Backlight)
The backlight used in the present embodiment includes the above-described light conversion member and a light source that can emit 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 suitably used as a backlight for a liquid crystal display device capable of obtaining a high luminance and a wide range of color reproducibility. 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, a blue LED light emitting element is more preferable, and a backlight capable of emitting white light is preferable.

(LCD panel)
The liquid crystal display panel used in the present embodiment is not particularly limited as long as it is a known liquid crystal display panel. The liquid crystal display panel displays an image by providing an alignment film between two glass plates provided with a polarizing filter, changing the direction of liquid crystal molecules by applying a voltage, and increasing or decreasing light transmittance.

  In the liquid crystal display device configured as described above, since the illumination light source of the present invention is used for the backlight, for example, the liquid crystal display panel can be illuminated with bright white light having a wide color gamut based on the three primary colors of light. Therefore, pure white with high luminance can be obtained on the display screen of the liquid crystal display panel, color reproducibility is good, and the quality of the display screen can be improved.

  Hereinafter, the present invention will be described in more detail based on Examples (Examples 8 to 11 and 14) and Comparative Examples (Examples 1 to 7, 12, and 13). However, the present invention is limited to these Examples and Production Examples. Is not to be done.

(Examples 1-14)
The raw materials of the respective components were prepared so as to have the compositions shown in Table 1 in terms of mol% based on oxides, and the glass raw materials were mixed. These were heated and melted in an electric crucible at 950 ° C. in a gold crucible, and a part of the melt was quenched with a rotating roll to form glass ribbons having two types of compositions. A part of the melt was cooled after molding to obtain a glass plate.
The obtained glass ribbon was pulverized with a ball mill, passed through a sieve having a mesh with an opening of 150 μm, and further subjected to air classification to obtain powders of glass 1 and 2 (glass powder). The obtained glass powder had a 50% particle size D ₅₀ of 1.3 μm and 1.2 μm, respectively.

The glass transition point Tg of the obtained glass powder was measured using a differential thermal analyzer (manufactured by Rigaku Corporation, trade name: TG8110).
Furthermore, after measuring the specific gravity d by Archimedes method, the obtained glass plate is processed into a plate shape having a thickness of 1 mm and a size of 20 mm × 20 mm, and both surfaces thereof are mirror-polished to obtain a sample plate, which has a refractive index with respect to light having a wavelength of 633 nm. n was measured using a Metricon model 2010 prism coupler.

As phosphor particles, 11 [mu] m 50% particle diameter _{D 50,} and Eu-activated CASN phosphor phosphor having a peak wavelength of about 628nm at 460nm excitation, 3 [mu] m 50% particle diameter _{D 50,} the phosphor peak wavelength at 460nm excitation An Eu-activated SrGa ₂ S ₄ phosphor having a wavelength of about 538 nm was used.

As the heat-resistant filler, 18 [mu] m 50% particle diameter _{D 50,} the refractive index at a wavelength of 633nm is a single crystal alumina which is 1.76, as nanofillers, an alumina 50% particle diameter _{D 50} is about 30nm, respectively. The 50% particle size D ₅₀ of the phosphor particles, heat-resistant filler and glass powder used in the examples was calculated by laser diffraction particle size distribution measurement (manufactured by Shimadzu Corporation, apparatus name: SALD2100).

  Glasses, phosphors, heat-resistant fillers and nanofillers are combined as shown in Tables 2 to 3, and phosphor particles are 20% in terms of volume fraction in terms of final solid content, and heat-resistant fillers and nanofillers are shown in Tables 2 to 3. Used in terms of volume fraction in terms of final solid content. First, a solvent and a vehicle were added to phosphor particles, a heat-resistant filler, and a nanofiller, followed by primary kneading. Next, the glass powder is added to the primary kneaded material and mixed so that the volume fraction in terms of the final solid content, which is the sum of the glass powder, phosphor particles, heat-resistant filler, and nanofiller, is 100%. Thus, a slurry was obtained. 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 4 cm square, and the PET film was peeled off to obtain a green sheet having a thickness of 0.5 to 0.7 mm.

  This green sheet was placed on a mullite substrate coated with a release agent, fired in the atmosphere at 380 ° C. for 4 hours, and then a light conversion member was produced under firing conditions as shown in Tables 2 to 3. Here, “Air” in the firing atmosphere represents air firing, and “LP” represents reduced-pressure firing with an ultimate vacuum of about 60 Pa.

For the quantum conversion yield of the light conversion member, the central part 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. Then, measurement was performed at an excitation light wavelength of 460 nm.
The total light transmittance of the light conversion member was measured with a C light source using a haze measuring device (manufactured by Suga Test Instruments Co., Ltd., trade name: haze meter HZ-2).
The adsorption rate of the nano filler is obtained by cleaving the obtained light conversion member, and observing the cross section in the thickness direction with SEM (manufactured by Hitachi High-Technologies Corporation, trade name: S-3000H) at a magnification of 5000 times, Obtained by calculation by image processing.

  These production conditions and characteristics of the light conversion member are also shown in Tables 2-3.

  From Tables 2 to 3, first, in CASN phosphors, Examples 8 to 11 as examples are in the range where the volume fraction of the nanofiller is 0.6 to 6.5%, and the adsorption rate of the nanofiller. Is 20 to 80%, maintaining a quantum conversion yield of 80% or more and a total light transmittance of 10% or more. Moreover, compared with Example 1 and Example 6 with the same baking conditions, the quantum conversion yield of Example 8 and Example 11 is high, and also Example 2, Example 4, Example 5 and Example 7 whose baking temperature is as high as 500 degreeC. In Example 9, the quantum conversion yield is significantly reduced, whereas in Example 9, since the high quantum conversion yield is maintained, the nanofiller has an effect of suppressing the thermal deactivation of the phosphor. I understand that. On the other hand, Example 12 in which the volume fraction of the nanofiller is over 6.5% shows a high quantum conversion yield, but the total light transmittance is as low as less than 10%, so that the light emission conversion efficiency is low. There is a fear.

Next, in the Eu-activated SrGa ₂ S ₄ phosphor, which is a sulfide phosphor, the quantum conversion yield is less than 80% in Example 13 where no nanofiller is used, whereas in Example 14, the quantum conversion is high. The yield was maintained, and it was found that the nanofiller also contributed to the effect of suppressing heat deactivation in the sulfide phosphor.

  The light conversion member and the method for producing the light conversion member of the present invention can reduce the labor and cost during production by a simple operation, can further suppress the deactivation of the phosphor during firing, and the light emission conversion efficiency. Can be provided at low cost. This light conversion member is suitable for use as a lighting application.

Claims (16)

A kneading step of kneading glass powder, phosphor particles, and nanofiller having a 50% particle size D ₅₀ of 50 nm or less,
A firing step of forming and firing the obtained kneaded product into a desired shape;
The manufacturing method of the light conversion member characterized by having.   A primary kneading step in which the kneading step kneads the phosphor particles and the nanofiller, and a secondary kneading step in which the glass powder is added and kneaded to the kneaded product obtained in the primary kneading step; The manufacturing method of the light conversion member of Claim 1 consisting of.   The method for producing a light conversion member according to claim 1 or 2, wherein a volume fraction of the nanofiller in the light conversion member is in a range of 0.6 to 6.5%.   The method for producing a light conversion member according to any one of claims 1 to 3, wherein the nanofiller is at least one nanofiller selected from the group consisting of silica, alumina, titania, zirconia, and magnesia. 5. The kneading step further kneads a heat-resistant filler having a 50% particle size D ₅₀ of 5 to 30 μm and a refractive index n of 1.5 to 2.5 at a wavelength of 633 nm. The manufacturing method of the light conversion member of Claim 1.   The phosphor particles have an excitation band at a wavelength of 400 to 500 nm, an emission peak at a wavelength of 500 to 700 nm, and an oxide, nitride, oxynitride, sulfide, oxysulfide, halide, aluminate The method for producing a light conversion member according to any one of claims 1 to 5, wherein the compound is one or more compounds selected from the group consisting of chlorides and halophosphates. The glass obtained from the glass powder is Bi ₂ O ₃ —B ₂ O ₃ —ZnO-based, The method for producing a light conversion member according to claim 1. The glass obtained from the glass powder contains Bi ₂ O ₃ 5 to 35%, B ₂ O ₃ 10 to 50%, ZnO 10 to 48% in terms of oxide-based mol%, Bi ₂ O ₃ and The method for producing a light conversion member according to claim 7, wherein the total amount of ZnO is 15% or more and less than 70%.   9. The method for producing a light conversion member according to claim 1, wherein the glass obtained from the glass powder has a refractive index of 1.70 to 2.20 at a wavelength of 633 nm. A light conversion member made of glass containing dispersed phosphor particles,
A light conversion member characterized in that a nano filler having a 50% particle size of 50 nm or less is adsorbed on the surface of the phosphor particles, and the adsorption rate is 20 to 80%. The glass, further, 50% particle size _{D 50} is 5 to 30 [mu] m, and in claim 10 in which the refractive index n at a wavelength of 633nm contains by dispersing heat-resistant filler is 1.5 to 2.5 The light conversion member as described.   The light according to claim 10 or 11, wherein the nanofiller is also dispersed in the glass, and the volume fraction of the nanofiller in the light conversion member is in the range of 0.6 to 6.5%. Conversion member.   The quantum conversion yield of the said light conversion member is 80% or more, The light conversion member of any one of Claims 10-12.   An illumination light source comprising: the light conversion member according to any one of claims 10 to 13; and a light source capable of irradiating light to the outside through the light conversion member.   The illumination light source according to claim 14, wherein the light source is an LED light emitting element. A liquid crystal display device comprising a liquid crystal display panel and a backlight for illuminating the liquid crystal display panel,
A liquid crystal display device comprising: the light conversion member according to any one of claims 10 to 13; and an illumination light source including a light source capable of irradiating light to the outside through the light conversion member.