JP2015201565A - Manufacturing method of optical conversion member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical conversion member capable of manufacturing the optical conversion member of which the quantum conversion yield is maintained excellent, by effectively recycling a molding that is discarded conventionally.SOLUTION: The manufacturing method of the optical conversion member includes: a first mixing step of mixing glass powder, a phosphor particle, a heat-resistant filler, a resin and an organic solvent to obtain a first mixture; a first molding step of molding the obtained first mixture in a desired shape to obtain a first molding; a second mixing step of dissolving the first molding in an organic solvent and mixing them while adjusting a viscosity to obtain a second mixture; a second molding step of molding the obtained second mixture in a desired shape to obtain a second molding; and a calcination step of calcinating the second molding to obtain the optical conversion member. A relational expression [P-D/G-D] of a 50% particle diameter G-Dof the glass powder and a 50% particle diameter P-Dof the phosphor particle ranges from 4 to 25.

Description

  The present invention relates to a method for manufacturing a light conversion member for converting the color of a light source.

  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.

  Such a light conversion member generally includes a kneading step of kneading glass powder, phosphor particles, a resin and an organic solvent into a kneaded product, a molding step of molding the obtained kneaded product into a desired shape, The molded product is fired to produce a light conversion member.

JP 2003-258308 A

  By the way, in the light conversion member, the management of the light conversion chromaticity is important, and the chromaticity of the light irradiated through the light conversion member is made uniform. In order to make this chromaticity uniform, the thickness of the light conversion member may be made uniform. That is, if there is unevenness in the thickness of the light conversion member, chromaticity unevenness is caused and light with a uniform color tone cannot be obtained. Therefore, in the manufacturing method of the light conversion member, in order to manufacture a high-quality light conversion member with little chromaticity unevenness, management of the thickness of the molded product obtained in the molding step is very important.

  However, in the molding step of molding the kneaded product, a liquid kneaded product is formed into a sheet shape so as to have a predetermined thickness, and the organic solvent is volatilized and molded. Therefore, it deviates from the predetermined thickness. Parts that are not of a predetermined thickness, such as both ends, were discarded without firing as non-standard. In addition, unlike the central part where the liquid physical properties of the kneaded product were stable, the end part at the initial stage of molding or the final stage of molding was unstable, resulting in a predetermined thickness or uneven thickness. Therefore, the end portion of the molded product formed into a sheet shape is almost discarded, and a central portion having a stable thickness is used for manufacturing a product.

  By the way, phosphor particles are generally expensive, and if the molded product is discarded in this way, the cost of the light conversion member becomes high because it is reflected in the manufacturing cost including the discarded portion. . In particular, the influence of the disposal of the phosphor particles is great, and a method for effectively utilizing the phosphor particles by reuse or the like has been demanded.

  Therefore, the present invention has been made in view of the above problems, and a method for producing a light conversion member capable of producing a light conversion member that can effectively reuse a molded article that has been conventionally discarded and that maintains a good quantum conversion yield. The purpose is to provide.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have made glass particles and phosphor particles, which are raw materials used for production, have a predetermined relationship between the particle sizes thereof. It was found that the molded product was dissolved again in an organic solvent and kneaded, and the resulting kneaded product was molded and fired to provide a light conversion member capable of maintaining a good quantum conversion yield. The present invention has been completed.

That is, the manufacturing method of the light conversion member of the present invention includes a first kneading step of kneading glass powder, phosphor particles, a heat-resistant filler, a resin and an organic solvent to obtain a first kneaded product, and a first obtained The first kneaded product is molded into a desired shape to form a first molded body, and the first molded body is dissolved in an organic solvent, kneaded while adjusting the viscosity, and second kneaded. A second kneading step for forming a product, a second molding step for molding the obtained second kneaded product into a desired shape to form a second molded body, and firing the second molded body. has a firing step of the optical converting member, a relation between the 50% particle size _{P-D 50} with the 50% particle size _{G-D 50} of the glass powder the phosphor particles _[P-D 50 / G -D _50] is characterized in that in the range of 4 to 25.

  According to the method for producing a light conversion member of the present invention, it is possible to effectively reuse a molded product that is outside the thickness management regulations that occurs when the kneaded product is molded. The light conversion member manufactured by this reuse can suppress a decrease in the quantum conversion yield and can be a light conversion member that can withstand practical use. Moreover, since the light conversion member obtained by the method for manufacturing a light conversion member of the present invention can be effectively used with a small amount of phosphor particles discarded, the manufacturing cost of the light conversion member can be reduced as compared with the conventional case. Furthermore, the price of an illumination light source, a liquid crystal display device, or the like to which this light conversion member is applied can be reduced.

Hereinafter, the manufacturing method of the light conversion member of this invention is demonstrated in detail.
[Production Method of Light Conversion Member]
The light conversion member obtained by the method for producing a light conversion member of the present invention transmits a part of the light emitted from the light source, converts the wavelength of the remaining light, and transmits the transmitted light and the wavelength-converted light. By synthesizing, a member that can irradiate light having a desired chromaticity to the outside. The 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.

  Such a light conversion member is composed of a sintered body of a mixed powder of glass powder, phosphor particles and a heat-resistant filler, and is generally a kneaded product (slurry) obtained by kneading the mixed powder with a resin and an organic solvent. ) Is formed into a desired shape and then fired to obtain a sintered body. The kneaded product is formed by applying the kneaded product to a transparent resin, volatilizing the organic solvent and drying it to obtain a sheet-like molded product (green sheet). The molded body obtained here is further sintered to form a light conversion member. In the present specification, the mixture of the resin and the organic solvent may be referred to as a vehicle.

  In the present invention, when the light conversion member is manufactured as described above, the light conversion member is intended to be manufactured again by reusing (recycling) the molded body that is out of the management regulations. By enabling reuse, the amount of phosphor particles discarded can be reduced and effectively used.

  In the present invention, as described above, first, a first kneading step of kneading glass powder, phosphor particles, a heat-resistant filler, a resin and an organic solvent into a first kneaded product, and the obtained first kneaded product are A first molding step in which the first molded body is molded into a desired shape, and the first molded body is dissolved in an organic solvent and kneaded while adjusting the viscosity to form a second kneaded product. Kneading step, second molding step of molding the obtained second kneaded product into a desired shape to form a second molded body, and firing the second molded body to produce a light conversion member The light conversion member is manufactured by the process.

First, the raw material used in manufacture of a light conversion member is demonstrated.
(Glass)
The glass used for the manufacturing method of this light conversion member will not be specifically limited if it is conventionally used for manufacture of a light conversion member.

  The glass used here preferably has a glass transition point Tg (hereinafter also simply referred to as “Tg”) of 300 to 550 ° C. When the glass transition point is higher than 550 ° C., the firing temperature becomes high during the manufacturing process of the light conversion member, and the uniform dispersibility of the phosphor particles may decrease due to shrinkage in cooling after firing. That is, the amount of phosphor particles present per unit area varies due to the difference in the degree of contraction between the central portion and the outer peripheral portion of the light conversion member, which causes chromaticity unevenness in the surface of the light conversion member. May occur. Or glass and fluorescent substance react and there exists a possibility that the quantum conversion yield of a light conversion member may fall. 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. Moreover, the light transmittance in the light conversion member may be reduced, and the light emission efficiency may be reduced. 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 used here preferably has a Bi ₂ O ₃ —B ₂ O ₃ —ZnO system as a main component. Among them, a glass containing Bi ₂ O _{3 3 to} 35%, B ₂ O ₃ 10 to 60%, ZnO 0 to 50% in terms of mol% based on oxide is more preferable.

_{Further, Bi 2 O 3 5~35%,} B 2 O 3 15~50%, ZnO 10~48%, SiO 2 0~35%, TeO 2 0~20%, Al 2 O 3 0~4%, MgO _{0~20%, CaO 0~20%, SrO} 0~20%, BaO 0~20%, Li 2 O 0~10%, Na 2 O 0~10%, K 2 O 0~10%, MnO 2 0 More preferred are glasses containing ˜0.5% and CeO ₂ 0-0.5%.

  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 the Tg and raises the refractive index without lowering the chemical durability of the glass, and is an essential component in this system. The content of Bi ₂ O ₃ is preferably _{3 to} 35%. If Bi ₂ O ₃ is less than 3%, the Tg of the glass powder is increased, which is not preferable. More preferably, it is 5% 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 _{3 to} 32%, further preferably 5 to 30%.

B ₂ O ₃ is a glass network former and is a component that can stabilize glass, and is an essential component in this system. The content of B ₂ O ₃ is preferably 10 to 60%. 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 60%, the chemical durability of the glass may be lowered. The content of B ₂ O ₃ is more preferably 15 to 50%, further preferably 20 to 40%.

  ZnO is a component that lowers Tg and raises the refractive index, and is not an essential component in this system. The content of ZnO is preferably 0 to 50%. If the content of ZnO exceeds 50%, vitrification becomes difficult, and glass production becomes difficult. The content of ZnO is more preferably 10 to 48%, further preferably 10 to 35%.

SiO ₂ is a component that increases the stability of the glass and is not an essential component in this system. The content of SiO ₂ is preferably 0 to 35%. If the content of SiO ₂ exceeds 35%, Tg may increase or the liquidus temperature may increase. The content of SiO ₂ is more preferably 0 to 20%, further preferably 0 to 10%. Since SiO ₂ may impair the sinterability in low-temperature firing at 500 ° C. or lower, it is preferable that SiO ₂ is not substantially contained.

TeO ₂ is a component that lowers the Tg, raises the refractive index, raises the weather resistance, and lowers the liquidus temperature, but is not an essential component in the present invention. 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, but is not an essential component in the present invention. 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 the glass and lower the Tg, and are not essential components in this system. 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.

Neither MnO ₂ nor CeO ₂ is an essential component in this system, but it is preferably contained because it functions as an oxidizing agent in the glass. In any case, reduction of Bi ₂ O ₃ in the glass can be prevented, so that this type of glass can be stabilized. Reduction of Bi ₂ O ₃ is not preferable because the glass is colored. 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%.

Alkali metal oxides of Li ₂ O, Na ₂ O and K ₂ O are components that lower Tg and are not essential components in this system. 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 1.65 to 2.10 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 2.05, still more preferably 1.75 to 2.00.

(Phosphor particles)
The type of phosphor particles used in the method for producing the light conversion member is not limited as long as the wavelength of the light source can be converted, and examples thereof include 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. Garnet-based crystals are excellent in water resistance and heat resistance, and are hardly deactivated in a slurry or deactivated during firing when undergoing the production process of the present invention described later. 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.

(Heat resistant filler)
The heat-resistant filler used in the method for producing the light conversion member can be used without particular limitation as long as it is a known heat-resistant filler used for the light conversion member. 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.

The average particle diameter of the heat-resistant filler (hereinafter, also referred to as the 50% particle size in this specification) _{F-D 50} 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 FD ₅₀ is more preferably 6 to 25 μm, still more preferably 8 to 22 μm. In the present specification, the 50% particle size D ₅₀ is a value calculated as a 50% value in the integrated% on a volume basis from the particle size distribution obtained by laser diffraction particle size distribution measurement.

  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.

Further, the heat resistant filler is preferably 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. 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.

  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.

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

  As described above, the light conversion member obtained by the production method of the present invention is configured by dispersing phosphor particles and heat-resistant filler in glass. In order to sufficiently suppress shrinkage during firing of the light conversion member, when the total amount of glass, phosphor particles and heat-resistant filler is 100%, the heat-resistant filler may contain 3 to 30% by volume fraction. preferable. 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 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.

  When kneading the above components, when the total amount of the phosphor particles, the heat-resistant filler and the glass powder is 100%, the content of each component in the mixed powder is a volume fraction, and the phosphor particles are 1 to 40%. The heat-resistant filler is preferably 3 to 30%, and the glass powder is preferably 50 to 96%.

  If phosphor particles are contained at 1% or more and glass powder at 96% 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.

  If the volume fraction of the phosphor particles is more than 40% and the volume fraction of the glass powder is less than 50%, 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 55% or more, further preferably 60% or more, and particularly preferably 65% or more.

  Moreover, it is preferable that the volume fraction of the heat-resistant filler is 3% or more because the shrinkage during firing of the light conversion member can be efficiently suppressed, and the state in which the phosphor particles are uniformly dispersed can be maintained. The volume fraction of the heat-resistant filler is more preferably 4% or more, further preferably 5% or more, and particularly preferably 7% or more. Further, if the volume fraction of the heat-resistant filler exceeds 30%, the sinterability of the mixed powder is impaired, and the transmittance of the light conversion member may be lowered. The volume fraction of the heat resistant filler is preferably 28% or less, more preferably 26% or less, still more preferably 20% or less, and particularly preferably 15% or less.

  A vehicle composed of a resin and an organic solvent may be mixed with the above-mentioned mixed powder in an amount that can be molded into a predetermined shape in the next molding step to form a kneaded product (slurry).

(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.

Hereinafter, in the method for manufacturing the light conversion member, each manufacturing process will be described in detail.
(First kneading step)
The first kneading step in the present invention involves kneading glass powder, phosphor particles, heat-resistant filler, resin and organic solvent to obtain a kneaded product (slurry), and it is sufficient that these raw materials can be kneaded uniformly. In this kneading, a known kneading method, for example, kneading using a dissolver, homomixer, kneader, roll mill, sand mill, attritor, ball mill, vibrator mill, high-speed impeller mill, ultrasonic homogenizer, shaker, etc. Good.

  Regarding the raw materials used here, the glass powder may be prepared by mixing a plurality of known glass powders so as to satisfy the above-mentioned glass composition, or the components are prepared so as to have predetermined thermal characteristics. Then, they may be mixed, melted in an electric furnace or the like, rapidly cooled to produce a glass having a predetermined composition, and this may be pulverized and classified.

At this time, the glass powder preferably has a 50% particle size GD ₅₀ of less than 2.0 μm. When the average particle size GD ₅₀ is 2.0 μm or more, the phosphor particles and the heat-resistant filler are not uniformly dispersed in the glass powder, and the light conversion efficiency is reduced when the light conversion member is used, or the shrinkage during firing The amount may increase. The average particle size GD ₅₀ is more preferably 1.5 μm or less, and still more preferably 1.4 μm or less.

Further, the maximum particle size _{GD max} of the glass powder is preferably 30 μm or less. When the maximum particle size GD _max is more than 30 μm, the phosphor particles and the heat-resistant filler are less likely to be uniformly dispersed in the glass powder, and when a light conversion member is produced, the light conversion efficiency of the phosphor decreases, There is a risk that the amount of shrinkage during firing may increase. _{GD max} is more preferably 20 μm or less, and further preferably 15 μm or less. In the present specification, _{GD max} is the value of the maximum particle size calculated by laser diffraction particle size distribution measurement.

The phosphor particles are the particles described above. The average particle size _{P-D 50} of the phosphor particles, 5 to 30 [mu] m is preferred. If the P—D ₅₀ of the phosphor particles is less than 5 μm, the specific surface area of the phosphor particles is increased, and there is a possibility that the phosphor particles are easily deactivated. The average particle size PD ₅₀ is more preferably 6 μm or more, further preferably 7 μm or more, and particularly preferably 8 μm or more. On the other hand, if the PD ₅₀ of the phosphor particles is more than 30 μm, the dispersibility is deteriorated in the light conversion member, the light conversion efficiency is deteriorated, and chromaticity unevenness may occur. Therefore, the average particle size PD ₅₀ is more preferably 20 μm or less, and even more preferably 15 μm or less.

Note that the 50% particle size _{P-D 50} 50% particle diameter _{G-D 50} of the glass powder of the phosphor particles, the following relationship _{[P-D 50 / G-} D 50] of 4 to 25 A range is required. The numerical range according to this relational expression is preferably 5 to 22, and more preferably 6 to 20. This is because in the production by reusing phosphor particles, which will be described later, the kneading step and the molding step are each performed at least twice, so that the phosphor particles and the glass powder repeatedly collide with each other. This is because the conversion yield decreases.

That is, it is considered that the ability to convert the wavelength of light is reduced due to damage to the surface of the phosphor particles. Therefore, so as to satisfy the above relationship, by 50% particle diameter P-D ₅₀ of the phosphor particles sufficiently larger than the 50% particle size G-D ₅₀ of the glass powder, by collision with the glass particles It was assumed that damage to the phosphor particles can be effectively reduced.

  When kneading the above components, when the total amount of the phosphor particles, the heat-resistant filler and the glass powder is 100%, the content of each component in the mixed powder is a volume fraction, and the phosphor particles are 1 to 40%. The heat-resistant filler is preferably 3 to 30%, and the glass powder is preferably 50 to 96%.

  If phosphor particles are contained at 1% or more and glass powder at 96% 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.

  If the volume fraction of the phosphor particles is more than 40% and the volume fraction of the glass powder is less than 50%, 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 55% or more, further preferably 60% or more, and particularly preferably 65% or more.

  Moreover, it is preferable that the volume fraction of the heat-resistant filler is 3% or more because the shrinkage during firing of the light conversion member can be efficiently suppressed, and the state in which the phosphor particles are uniformly dispersed can be maintained. The volume fraction of the heat-resistant filler is more preferably 4% or more, further preferably 5% or more, and particularly preferably 7% or more. Further, if the volume fraction of the heat-resistant filler exceeds 30%, the sinterability of the mixed powder is impaired, and the transmittance of the light conversion member may be lowered. The volume fraction of the heat resistant filler is preferably 28% or less, more preferably 26% or less, still more preferably 20% or less, and particularly preferably 15% or less.

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

  And in order to manufacture this light conversion member as a sintered compact, the 1st kneading | mixing which knead | mixes the glass powder which is the above-mentioned raw material, fluorescent substance particle, a heat-resistant filler, resin, and an organic solvent as a 1st kneaded material is carried out. A first molding step in which the obtained first kneaded product is molded into a desired shape to form a first molded body, an organic solvent is added to the first molded body and kneaded, and a second A second kneading step for forming a kneaded product, a second molding step for forming the obtained second kneaded product into a desired shape to form a second molded body, and firing the second molded body. What is necessary is just to perform sequentially the baking process used as a light conversion member.

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

  A 1st molded object (green sheet) can be manufactured in the following processes, for example. Glass powder, phosphor particles and heat-resistant filler are kneaded in a vehicle and defoamed to obtain a slurry. The obtained slurry is coated on a transparent resin by a doctor blade method and dried. After drying, it is cut into a desired size and the transparent resin is peeled off to obtain a molded body (green sheet). Furthermore, by pressing these to form a laminate, a molded body having a desired thickness can be secured.

  Here, the transparent resin for applying the slurry is not particularly limited as long as it has releasability. The transparent resin used here is preferably a transparent film having a uniform thickness so that a green sheet having a uniform thickness can be obtained. Examples of such a transparent film include a PET film. It is done.

  The first molded body obtained here is formed by forming a liquid kneaded material in a sheet shape so as to have a predetermined thickness, putting it in a drying furnace, and volatilizing the organic solvent. In this case, liquid kneading of the kneaded product occurs, so that a portion deviating from a predetermined thickness is formed. What is necessary is just to process the part which is not predetermined thickness like this both ends by the following 2nd kneading | mixing process. Also, the end portion at the initial stage of molding or at the final stage of molding is unstable unlike the central portion where the liquid property of the kneaded material is stable, and it may not have a predetermined thickness, or uneven thickness may occur. What is necessary is just to make it process in a kneading | mixing process. In addition, what is necessary is just to sinter the 1st molded object which has predetermined | prescribed thickness by a baking process conventionally, and to make it a light conversion member.

(Second kneading step)
In the second kneading step in the present invention, the first molded body obtained in the first molding step is dissolved in an organic solvent and kneaded while adjusting the viscosity to obtain a second kneaded product (slurry). Therefore, it is only necessary that the raw material constituting the first molded body (the raw material used in the first kneading step) can be uniformly kneaded again.

  In this kneading, first, after measuring the weight of the first molded body, it is necessary to sufficiently dissolve in the organic solvent. Therefore, a relatively large amount of organic solvent is used. Thus, the organic solvent which melt | dissolved the 1st molded object is generally a liquid with a small viscosity. Therefore, in order to obtain the second kneaded product, the organic solvent is volatilized and kneaded while adjusting the viscosity to obtain a second kneaded product. At this time, a vehicle may be added.

  Further, at this stage, if necessary, glass powder, phosphor particles and heat-resistant filler as raw materials for the light conversion member can be added to adjust the raw material ratio and the viscosity of the kneaded product. Furthermore, you may change the quantity and kind of fluorescent substance so that it may become chromaticity different from a 1st molded object. The viscosity adjusted at this time is preferably about the same as that of the first kneaded product, and may be a viscosity suitable for forming a desired shape in the next second molding step.

  The first molded body used here is a part of the first molded body as described above, and the first molded body that is not used for manufacturing the light conversion member as it is outside the management regulations. It is preferable that it is a body.

(Second molding step)
The second molding step in the present invention is to mold the second kneaded product (slurry) obtained in the second kneading step into a desired shape. The molding method is not particularly limited as long as a desired shape can be imparted, and examples thereof include known methods such as a press molding method, a roll molding method, and a doctor blade molding method. The second molded body (green sheet) obtained by the 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 second molded body can be obtained by the same operation as the molding of the first molded body described in the first molding step.

  In the second molding step, as in the first molding step, a portion that cannot be obtained as the predetermined thickness appears. Therefore, such a second molded body is changed to the third kneading step and the second step. It is good also as a light conversion member by processing by the 3 shaping | molding process or the process beyond it, and the baking process demonstrated below. However, since the quantum conversion yield decreases as the kneading process and the molding process are repeated, it is preferable to perform the treatment with as few repetitions as possible so as to satisfy the required product characteristics.

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

As long as the firing step can be performed to form a glass body, the conditions are not particularly limited, but the firing atmosphere is preferably a reduced pressure atmosphere of 10 ³ Pa or less or an atmosphere having an oxygen concentration of 1 to 15%. 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 quantum conversion yield of the light conversion member thus obtained 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.

  Moreover, since this light conversion member increases a manufacturing process with respect to the conventional light conversion member obtained by baking a 1st molded object, the quantum conversion yield is the quantum conversion yield of the conventional light conversion member, and Although reduced in comparison, the reduction rate can be kept low. For example, the reduction rate is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

  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 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 converting member is preferably plate-shaped, that is, the cross-sectional shape is rectangular. The smaller the variation in the plate thickness within the light conversion member, the smaller the in-plane color variation, which is preferable.

[Light source]
By combining the light conversion member and the light source obtained in this way and arranging the light source so that light can be emitted to the outside through the light conversion member, it can be used as an illumination light source that emits a desired color. The light conversion member is preferably placed 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]
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. 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 is used for the backlight, the liquid crystal display panel can be illuminated with, for example, bright white light. In addition, a white panel with sufficient luminance on the display screen of the liquid crystal display panel can be manufactured at a lower cost than in the past.

  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. Here, Examples 1, 3, and 5 are reference examples of manufacturing methods of conventional light conversion members. On the other hand, Example 2 is an example (one subjected to the second kneading step and the second molding step and fired after Example 1), and Example 4 is an example (second compared to Example 3). Example 6 was fired after being subjected to the kneading step and the second molding step), and Example 6 was a comparative example (what was fired after being subjected to the second kneading step and the second molding step with respect to Example 5). It is.

The raw materials used in the reference examples, examples and comparative examples are as follows.
<Phosphor particles>
As phosphor particles, a Ce-activated YAG phosphor (phosphor 1) having a 50% particle size PD ₅₀ of 10 μm and a phosphor peak wavelength of about 555 nm when excited at 460 nm, and a 50% particle size PD ₅₀ of 11 μm. Eu-activated CASN phosphor (phosphor 2) having a phosphor peak wavelength of about 628 nm upon excitation at 460 nm, and Ce having a 50% particle size PD ₅₀ of 4 μm and a phosphor peak wavelength of about 560 nm upon excitation at 460 nm An activated YAG phosphor (Phosphor 3) was used.

<Heat resistant filler>
As the heat-resistant filler, single crystal alumina having a 50% particle size FD ₅₀ of 18 μm was used.

<Glass powder>
The glass raw materials were mixed so that Bi ₂ O ₃ 21%, B ₂ O ₃ 35%, ZnO 37%, MgO 2%, TiO ₂ 1%, TeO ₂ 4% in terms of mol% based on oxide. This was heated in an electric furnace to 900 ° C. to 1000 ° C. in a gold crucible and melted, and the melt was quenched with a rotating roll to form a glass ribbon. The glass ribbon was pulverized with a ball mill, passed through a sieve having a mesh with a mesh size of 150 μm, and further subjected to airflow classification to obtain glass powder (glass powder) having a 50% particle size GD ₅₀ of 1.2 μm. Moreover, the glass transition point Tg of this glass powder was 415 degreeC.

The glass transition point Tg of the obtained glass powder was measured using a differential thermal analyzer (manufactured by Rigaku Corporation, trade name: TG8110). The phosphor particles, heat-resistant filler and glass powder 50% particle size D ₅₀ (PD ₅₀ , FD ₅₀ and GD ₅₀ ) are measured by laser diffraction particle size distribution measurement (manufactured by Shimadzu Corporation, apparatus name). : SALD2100).

(Examples 1, 3, 5; reference examples)
Glass, phosphor particles, and heat-resistant filler were mixed in the combinations and ratios shown in Table 1, and an organic solvent and a vehicle were kneaded and defoamed to obtain a slurry. As the vehicle, a solution in which 25 parts by mass of an acrylic resin was dissolved in 75 parts by mass of a mixed solvent of toluene, xylene, isopropanol, and 2-butanol was used. Further, a mixed solvent of toluene, xylene, isopropanol and 2-butanol was used as an organic solvent for dilution, and the slurry viscosity was adjusted to about 5000 cP. This slurry was applied to a PET film (manufactured by Teijin Limited) to a width of about 90 mm and a length of about 1500 mm by the doctor blade method. This was dried in a drying furnace for about 30 minutes, and the PET film was peeled off to obtain a green sheet.

  When the thickness of the obtained green sheet was measured, the thickness of the central portion where the thickness was stable was 0.45 mm, which is a target value. With respect to this value, the range within ± 0.01 mm was defined as the management regulation value. The green sheet that falls within the range of this management regulation value had a width of about 70 mm and a length of 800 to 1000 mm. A portion of the green sheet that satisfies this control regulation value is cut out in a square of about 70 mm, placed on a mullite substrate coated with a release agent, baked at 320 ° C. for 4 hours, baked at 460 ° C. for 1 hour, and converted into a light conversion member. Manufactured. The thickness of the obtained light conversion member was about 0.15 mm.

(Examples 2, 4; Examples, Example 6; Comparative Examples)
In each of Examples 1, 3, and 5, the green sheet whose green sheet thickness did not fall within the range of 0.45 ± 0.01 mm was shredded, the organic solvent for dilution was added, and the mixture was mixed with a centrifugal mixer at 2000 rpm, 20 Minute kneading was repeated twice to dissolve the green sheet. The obtained slurry precursor is sampled, and when the viscosity is low so that it becomes about 20 Pa · s at 10 rpm by a digital rotary viscometer, the organic solvent is volatilized with a vacuum pump, and when the viscosity is high, the organic solvent and A vehicle was added and kneaded to obtain a slurry (second kneading step). This slurry was molded (second molding step) and fired in the same manner as in Examples 1, 3, and 5, to produce a light conversion member. The thickness of the obtained light conversion member was about 0.15 mm.

(Test example)
About the obtained light conversion member of Examples 1-6, the quantum conversion yield and chromaticity coordinate x, y were measured. These results are also shown in Table 1.

  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. At the same time, chromaticity coordinates x and y are also obtained.

  As is apparent from Table 1, Examples 1, 3, and 5 are based on conventional conventional manufacturing methods, and the quantum conversion yield and chromaticity coordinates of the obtained light conversion member have target characteristics. It has become. On the other hand, in Examples 2, 4, and 6, since the kneading step and the forming step were further performed once for the kneading step and the forming step, the quantum conversion yield tends to decrease. However, the decrease in the quantum conversion yield is suppressed to within 5% for Example 2 compared to Example 1 and Example 4 compared to Example 3, respectively, and it can be confirmed that they are sufficiently practical. It was. Also, the change in chromaticity is good because both x and y are less than 0.02.

  On the other hand, in Example 6, the decrease in quantum conversion yield is more than 5% compared to Example 5, and the decrease is remarkable. Also, the change in chromaticity is a large y value of 0.02 or more.

From the above, in the raw materials used, and the 50% particle size G-D ₅₀ 50% particle diameter P-D ₅₀ and the glass powder of the phosphor particles, that to satisfy the predetermined relationship, the kneading process and molding It was found that the quantum conversion yield can be kept high even if the process is repeated.

  Since the light conversion member of the present invention has a high quantum conversion yield, it is suitable for use as a lighting application by converting light from a light source into a desired color.

Claims (4)

A first kneading step of kneading glass powder, phosphor particles, heat-resistant filler, resin and organic solvent into a first kneaded product;
A first molding step in which the obtained first kneaded product is molded into a desired shape to form a first molded body;
A second kneading step of dissolving the first molded body in an organic solvent and kneading while adjusting the viscosity to form a second kneaded product;
A second molding step of molding the obtained second kneaded product into a desired shape to form a second molded body;
A firing step of firing the second molded body to obtain a light conversion member;
Have
Said relational expression between the 50% particle size _{P-D 50} with the 50% particle size _{G-D 50} of the glass powder the phosphor particles _{[P-D 50 / G-} D 50] is in the range of 4 to 25 The manufacturing method of the light conversion member characterized by these.   When the total amount of the phosphor particles, the heat-resistant filler and the glass powder is 100%, the phosphor particles are 1 to 40%, the heat-resistant filler is 3 to 30%, and the glass powder is a volume fraction. The manufacturing method of the light conversion member of Claim 1 which contains 50 to 96%.   The method for manufacturing a light conversion member according to claim 1 or 2, wherein the first molded body used in the second kneading step is a part of the first molded body obtained in the first molding step. . The glass powder is by _{mol%, Bi 2 O 3 3~35%,} B 2 O 3 10~60%, light according to claim 1 containing 0 to 50% ZnO Manufacturing method of conversion member.