JP2015053471A - Manufacturing method of optical conversion member, optical conversion member, illumination light source, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical conversion member with which a molding is applied with pressure during firing to suppress the deformation, and sufficient decalcification can be performed, and an optical conversion member that can be obtained by the manufacturing method.SOLUTION: A manufacturing method of an optical conversion member includes the steps of kneading glass powder, phosphor particles, resin, and solvent to obtain kneaded material 1, and subsequently molding the obtained kneaded material 1 into a desired shape and firing a resulting molding, in which the kneaded material 1 is fired while being held between two base materials 2 having a porosity of 15 to 60%.

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.

  This light conversion member is generally prepared by mixing glass powder and inorganic phosphor powder, adding a resin binder to the mixture to form a kneaded product, and molding the kneaded product into a desired shape by pressure molding. It is obtained by firing the green body. Usually, this baking is performed so that slurry formed on a baking base material (mounting table) called a setter can be sufficiently deashed with the upper surface and side surfaces free.

  Moreover, in order to improve the dimensional accuracy, such as desired thickness and shape, about the light conversion member obtained by baking, the manufacturing method which improves the dimensional accuracy of a shape by repressing after baking is known (patent document) 2). According to this manufacturing method, surface scratches and dents can be further flattened, polishing and grinding steps can be omitted, and a light conversion member with high surface accuracy can be easily manufactured at low cost.

JP 2003-258308 A International Publication No. 2009/104356 Pamphlet

  However, in such a method for producing a light conversion member, since the transmittance of glass is important, sintering is performed at a high temperature in order to suppress generation of voids and the like during firing. However, if the temperature is raised too high at this time, the surface temperature distribution of the molded product of the kneaded product becomes large, and the difference in heat shrinkage rate may increase in the subsequent cooling, which may cause deformation. When the body is plate-shaped (sheet-shaped), the deformation is remarkable. In order to suppress such deformation, it is conceivable to prevent deformation by applying a predetermined pressure. However, in the manufacture of a light conversion member using a kneaded material containing a resin, it is necessary to deash during firing. For this reason, there is a problem that decalcification failure occurs simply by applying pressure. In the present specification, “demineralization” means that organic substances derived mainly from resin are blown away so that the organic substances are not contained in the light conversion member.

  Then, this invention aims at provision of the light conversion member obtained by the manufacturing method of the light conversion member which can suppress a deformation | transformation by pressing a molded object at the time of baking, and can also fully deash, and the manufacturing method And

  In Patent Document 2, a member having various shapes is manufactured with high dimensional accuracy by repressing (pressurizing) in the manufacture of the light conversion member. The press precursor is re-molded into a predetermined shape by hot pressing using a mold, and is not performed at the time of sintering, and the technical relevance to the present invention is low.

  As a result of intensive studies by the present inventors, it has been found that, in the production of a light conversion member, deformation can be suppressed by pressing a molded body with a predetermined base material during sintering, and deashing can be performed without any problem. It came to be completed.

  That is, in the method for producing a light conversion member of the present invention, glass powder, phosphor particles, resin, and solvent are kneaded to obtain a kneaded product, and then the obtained kneaded product is formed into a desired shape and then fired. A method for producing a light conversion member, characterized in that the kneaded product is fired while being sandwiched between two substrates having a porosity of 15 to 60%.

  The light conversion member of the present invention is a light conversion member made of glass containing phosphor particles dispersed therein, and is obtained by the method for producing a light conversion member of the present invention.

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 can produce a light conversion member having a good quantum conversion yield by suppressing deformation of the light conversion member and performing sufficient decalcification by a simple operation. It is what. Therefore, the product manufacturing yield can be improved.

  Since the light conversion member of the present invention is sufficiently decalcified and free from voids as described above, the quantum conversion yield is good, the deformation is suppressed, and the characteristics are stable. Since the illumination light source of the present invention uses such a light conversion member, 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.

It is a figure explaining the baking process which is one Embodiment of this invention. It is the figure which provided the spacer between the base materials in the baking process of FIG.

  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.

<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 and phosphor particles, and more specifically, a kneaded product obtained by kneading the mixed powder, a resin and an organic solvent is fired. It consists of a sintered body obtained in this way.

  Thus, in order to produce this light conversion member as a sintered body, a kneading step of kneading glass powder, phosphor particles, resin and organic solvent to obtain a kneaded product, and obtaining the kneaded product in a desired shape After forming into a molded body, the molded body may be fired to form 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 shrinkage or a decrease in quantum conversion yield, the Tg of the glass is preferably 520 ° C. or lower, more preferably 500 ° C. or lower, and further preferably 480 ° C. or lower.

  On the other hand, when the glass transition point Tg is less than 300 ° C., the firing temperature is low, and the decalcification temperature is higher than the temperature at which the glass flows. Therefore, the carbon content in the light conversion member increases, and the light conversion member 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, as represented by mol% based on _{oxides, Bi 2 O 3 5~35%,} B 2 O 3 10~50%, ZnO 10~48%, more preferably glass containing.

_{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. There is no particular lower limit, but 0.5 μm or more is preferable.

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 size of the phosphor particles is less than 1 μm, the specific surface area of the phosphor particles is increased, and there is a possibility that the phosphor particles are easily deactivated. 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, when the 50% particle size of the phosphor particles is more than 30 μm, the dispersibility is deteriorated in the light conversion member, the light conversion efficiency is deteriorated, and chromaticity unevenness may occur. Therefore, the 50% particle size is more preferably 20 μm or less, and even more preferably 15 μm or less.

(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. In the present specification, the mixture of the resin and the organic solvent may be referred to as a vehicle.

Next, each process in the manufacturing method of the light conversion member of this embodiment is demonstrated. The firing process will be described with reference to FIG.
[Kneading process]
The kneading step in the present embodiment is a method of kneading the above glass powder, phosphor particles, resin and organic solvent to form a slurry kneaded material, and it is sufficient that 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.

  When kneading the above components, when the total amount of the phosphor particles and the glass powder is 100%, the content of each component in the mixed powder is the volume fraction, the phosphor particles are 1 to 40%, and the glass powder Is preferably 60 to 99%.

  If phosphor particles are contained at 1% or more and glass powder at 99% 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 95% or less, still more preferably 93% or less, and particularly preferably 90% or less.

  If the volume fraction of the phosphor particles is more than 40% and the volume fraction of the glass powder is less than 60%, the sinterability of the mixture of the phosphor particles and the glass powder is impaired, and the transmittance of the light conversion member is low. There is a risk. 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 65% or more, further preferably 70% or more, and particularly preferably 75% or more.

  In addition, what is necessary is just to mix the quantity which becomes a viscosity of the grade which can be shape | molded by the following shaping | molding process with respect to the said mixed powder and resin and an organic solvent into a slurry-like kneaded material.

[Baking process]
In the firing step in the present invention, the kneaded product obtained in the kneading step is molded into a desired shape, and then the kneaded product is fired. 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. The doctor blade molding method is preferable because a light conversion member having a uniform film thickness can be efficiently manufactured in a large area.

  For example, it can be manufactured by the following steps. Glass powder and phosphor particles 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. The molded body of the kneaded product is obtained in a desired shape, but in order to sufficiently decalcify, a sheet shape having a thickness of 1 mm or less is preferable, and the thickness is preferably 0.1 to 0.8 mm. When the thickness exceeds 1 mm, there is a problem that it is difficult to deash. In addition, when the thickness is 1 mm or less, it is warped and greatly deformed if not sandwiched between the substrates as in the present invention, but there is no such problem in the present invention.

  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 molded body of the obtained kneaded product is fired. In this firing, the mixed powder is sintered to obtain a glass containing dispersed phosphor particles. In the present invention, this firing operation is characteristic and, as shown in FIG. 1, firing is performed while sandwiching the molded product 1 of the kneaded material between the base materials 2. In addition, what is necessary is just to manufacture a glass body like the well-known baking method about the other baking conditions.

  The base material 2 used here only needs to be able to sandwich the molded body 1 of the kneaded product, and the shape may be matched with the shape of the light conversion member to be manufactured. ), And the substrate has a plate shape. Deformation can be suppressed by sandwiching such a light conversion member from above and below with a base material and firing. That is, it is only necessary to apply a pressure larger than the force with which the molded body of the kneaded product is deformed during firing using two base materials.

  The substrate 2 is formed of a heat-resistant member that does not deform with respect to the firing temperature and the pressure applied during firing, and is a porous body having a porosity of 15 to 60%. For example, porous ceramics are preferable. . Examples of porous ceramics include alumina, mullite, magnesia, cordierite, zirconia, and yttria. By using the porous body in this way, deashing can be sufficiently performed from the kneaded product. If the porosity is less than 15%, deashing may be insufficient, and if it exceeds 60%, the pore diameter on the surface of the substrate increases, and the shape is transferred to the light conversion member. There is a possibility that the extraction efficiency becomes insufficient. The surface pore diameter is preferably 5 μm or less, for example. In the present specification, “porosity” is an apparent porosity measured according to JIS R2205.

  If the pressure applied to the molded body 1 of the kneaded material by the base material 2 can suppress deformation, the lower base material is fixed and the upper base material is placed on the molded body of the kneaded material. Only the pressure due to the weight of the material may be applied, or a larger pressure may be applied in order to suppress deformation more effectively. At this time, the pressure applied to the molded body of the kneaded product is preferably, for example, 20 to 500 Pa. If this pressure is less than 20 Pa, there is a possibility that an effect is not seen with respect to shrinkage deformation at the time of firing of the light conversion member. This pressure is more preferably 40 Pa or more, and further preferably 50 Pa or more. On the other hand, when the pressure exceeds 500 Pa, the pressure is too large and is restrained by the shrinking process during firing. Therefore, stress is applied in the plane direction of the light conversion member, and the light conversion member may be damaged. This pressure is more preferably 400 Pa or less, and even more preferably 300 Pa or less.

  And baking operation is performed in the state which applied the pressure with the base material 2 as mentioned above. If the glass body is obtained at this time, 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 is obtained as a light conversion member having a desired shape, in which phosphor particles are dispersed in glass, and the shape of the light conversion member is suppressed from deformation due to a difference in shrinkage rate. The method for producing a light conversion member of the present invention is an excellent invention that enables the light conversion member to be produced in a desired shape by suppressing deformation by a simple operation.

  In addition, at the time of this baking, it is preferable to arrange | position the spacer 3 between the base materials 2 because control of the thickness of the light conversion member obtained by baking is easy and stable. FIG. 2 shows an example in which the spacer 3 is disposed between the base materials 2.

  The spacer 3 used at this time is preferably formed of a heat-resistant member that does not deform with respect to the firing temperature and the pressure applied during firing, for example, stainless steel foil such as SUS, titanium foil, titanium alloy foil, nickel alloy foil, Examples thereof include metal foil such as aluminum alloy foil and zirconium foil, and a ceramic molded body similar to the base material 2. Among the stainless steel foils, tempered products such as SUS430 and SUS310S are preferable from the viewpoints of easy availability, cost, precision of plate thickness control, heat resistance, and the like.

  The thickness of the spacer 3 is preferably set to the same thickness as the “target thickness of the light-converting member after firing”, and the shape of the spacer 3 can be arranged so that the contact surfaces of the two base materials 2 with the kneaded material are arranged in parallel. What is necessary is just a thing, and it is preferable that it is plate shape. Furthermore, when it is desired to precisely control the target thickness of the light-converting member after firing, the thickness accuracy of the spacer 3 is preferably within ± 3 μm.

<Light conversion member>
Next, the light conversion member of this embodiment will be described. This light conversion member is obtained by the above manufacturing method and is made of glass containing dispersed phosphor particles. 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.

  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. When 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 method of this invention is used, a light conversion member with thin thickness can be obtained.

  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.

  In the above description, the case where glass powder and phosphor particles are used as the powder raw material has been described, but a heat-resistant filler may be further added and mixed. Mixing a heat-resistant filler is preferable because deformation due to thermal shrinkage during firing can be suppressed.

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, when the phosphor particles and the heat-resistant filler are dispersed in the glass, the glass, the phosphor particles, and the heat-resistant filler are sufficiently suppressed in order to sufficiently suppress the shrinkage during firing of the light conversion member. When the total amount is 100%, it is preferable to contain 3 to 30% of heat-resistant filler in volume fraction. 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 to contain 50 to 96% of glass and 1 to 40% of phosphor particles 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.

<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.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example and a comparative example, this invention is limited to these Examples and manufacture examples, and is not interpreted. Table 1 shows glass compositions used for the light conversion member of the present invention, and Table 2 shows examples (Examples 4 to 9) and comparative examples (Examples 1 to 3 and 10).

  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 glass raw materials were mixed. Glass 1 is heated in an electric furnace to 1200 ° C. in a platinum crucible, and glass 2 and 3 are heated and melted in an electric furnace to 950 ° C. in a gold crucible, and a part of the melt is rapidly cooled with a rotating roll. A glass ribbon was formed. A part of the melt was cooled after molding to obtain a glass plate.

The obtained 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 airflow to obtain powders (glass powder) of glasses 1 to 3. The obtained glass powder had a 50% particle size D ₅₀ of 1.2 μm, 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. n was measured using a Metricon model 2010 prism coupler.

As phosphor particles, 10 [mu] m 50% particle diameter _{D 50,} and YAG phosphor phosphor having a peak wavelength of about 555nm at 460nm excitation, is 50% particle diameter _{D 50} 11 [mu] m, the phosphor peak wavelength at 460nm excitation about 628nm A CASN phosphor was used.

  In a combination of glass and phosphor as shown in Table 2, glass powder and phosphor particles are mixed at a volume fraction of 80:20, kneaded with vehicle and solvent, defoamed and slurried Got. This slurry was applied to a PET film (manufactured by Teijin Limited) by the doctor blade method. In Example 8, the volume fraction of YAG phosphor particles and CASN phosphor particles was 9: 1 out of the volume fraction of phosphor particles of 20%. Each obtained slurry 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. A green sheet was obtained so as to have a thickness.

  Prepare a base material of the material and porosity as shown in Table 2, apply a release agent on it and place or sandwich a green sheet, and light-convert it under firing conditions as shown in Table 2. A member was manufactured. As the substrate, a substrate having a shape of about 150 mm × 150 mm and a thickness of 3 to 5 mm was used. Here, “upper and lower” in the substrate arrangement indicates that it is sandwiched, and “lower” indicates that the substrate is opened without placing the substrate on the upper side. When a large pressure was applied to the molded body during firing, the pressure was adjusted by placing a weight on the upper substrate. At this time, the initial firing pressure applied to the molded body was calculated on the assumption that the weight of the base material and the weight placed on the green body was evenly applied to the entire area of the green sheet. Moreover, the SUS430 foil which performed the tempering process was used for the spacer. Two types of shapes, a length of 100 mm and a width of 10 mm, with a thickness of 150 μm and 200 μm were prepared. In Table 2, “None” for the spacer indicates that no spacer was arranged around the green sheet. Furthermore, “Air” in the firing atmosphere indicates air firing, and “LP” indicates 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 thickness of the light conversion member was measured with a micrometer.

  In Table 2, Example 10, which is a comparative example, warped downward to a convex shape after firing and about 2 cm in height difference, and it was difficult to measure the quantum conversion yield and the thickness of the light conversion member.

  On the other hand, in Examples 4 to 9 in which the porosity of the substrate is in the range of 15 to 60%, a high quantum conversion yield of 80% or more is obtained regardless of whether the phosphor is YAG or CASN. Further, in Examples 4 to 6, 8 and 9 in which spacers are arranged, the thickness of the light conversion member is within ± 10 μm of the arranged spacers, which indicates that the thickness can be controlled by this method. However, Examples 1-3 in which the porosity of the substrate was less than 15% showed a low value with a quantum conversion yield of less than 80%. This is because there is a base material on the upper side at the time of firing, so that decalcification is not sufficiently performed, and carbon remains in the light conversion member. The color of the light conversion member was also black in Example 1 and brown in Example 2.

  As mentioned above, according to the manufacturing method of the light conversion member of this invention, the light conversion member of the desired shape which maintained the quantum conversion yield can be manufactured stably by simple operation, and a yield can be improved. . Moreover, it turned out that the light conversion member obtained by this method has a high quantum conversion yield, and has the stable characteristic.

  The method for producing a light conversion member of the present invention is capable of stably producing a light conversion member in a desired shape by suppressing deformation due to a difference in shrinkage rate during firing. Since the light transmittance is also good, the light emission conversion efficiency can be maintained high, and it is suitable for use as a lighting application.

DESCRIPTION OF SYMBOLS 1 ... Molded object of kneaded material, 2 ... Base material, 3 ... Spacer

Claims (11)

A kneaded product obtained by kneading glass powder, phosphor particles, a resin and a solvent, and then molding the obtained kneaded product into a desired shape, followed by firing.
A method for producing a light conversion member, wherein the kneaded product is fired while being sandwiched between two substrates having a porosity of 15 to 60%.   The method for producing a light conversion member according to claim 1, wherein the kneaded product is dried before firing.   The manufacturing method of the light conversion member of Claim 1 or 2 which shape | molds the said kneaded material in a sheet form.   The manufacturing method of the light conversion member of any one of Claims 1-3 which apply the pressure of 20-500 Pa to the molded object of the said kneaded material by pinching | interposing between the said 2 base materials.   The method for producing a light conversion member according to any one of claims 1 to 4, wherein a spacer having a predetermined thickness is provided between the two base materials and fired.   The said base material is porous ceramics, The manufacturing method of the light conversion member of any one of Claims 1-5. A light conversion member made of glass containing dispersed phosphor particles,
It is obtained by the manufacturing method of the light conversion member of any one of Claims 1-6, The light conversion member characterized by the above-mentioned.   The light conversion member according to claim 7, wherein a quantum conversion yield of the light conversion member is 80% or more.   An illumination light source comprising the light conversion member according to claim 7 and a light source capable of irradiating light to the outside through the light conversion member.   The illumination light source according to claim 9, 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 claim 7 or 8; and an illumination light source including a light source capable of irradiating light to the outside through the light conversion member.

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