JPWO2014104286A1 - Coated phosphor particles and method for producing the same - Google Patents

Abstract

At least a part of the surface of the phosphor particles is covered with a hydrolyzate of a prepolymer produced by a condensation reaction between a polydimethylsiloxane having a silanol group at at least one end and an oligomer of a metal and / or metalloid alkoxide. The coated phosphor particles thus formed have high emission intensity when excited with light having a wavelength of 350 to 430 nm, and emit light with little decrease over a long period of time.

Description

  The present invention relates to coated phosphor particles and a method for producing the same.

  Phosphors are widely used as visible light sources for white LEDs. As a white LED, a combination of a semiconductor light emitting device that emits blue light by applying electric energy and a yellow light emitting phosphor is used to excite the yellow light emitting phosphor by blue light from the semiconductor light emitting device and the blue light. A two-color mixed type that obtains white light by mixing with the generated yellow light is widely used. However, there is a problem that the white light emitted from the two-color mixed type white LED has low purity. For this reason, recently, a semiconductor light emitting device combining a semiconductor light emitting element that emits light with a wavelength of 350 to 430 nm by applying electric energy and three types of phosphors of a blue light emitting phosphor, a green light emitting phosphor, and a red light emitting phosphor has been combined. Development of a three-color mixed type white LED that obtains white light by mixing three colors of blue light, green light, and red light generated by exciting the respective phosphors with light from the element has been performed.

In Patent Document 1, as phosphor particles having high moisture resistance and capable of suppressing a decrease in luminance after storage, Ln as an activator for a compound represented by the following formula (1) (where Ln is Ce, A particulate fluorescent material (A) containing Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Mn.) The phosphor particle which consists of Si containing compound (B) mounted as a particle | grain on the surface or in a layer form is described.
3M ¹ O · mM ² O · nM ³ O ₂ (1)
(However, M ¹ in the formula (1) is one or more of Ca, Sr, and Ba, M ² is Mg and / or Zn, M ³ is Si and / or Ge, and the value of m is 0. 0.9 to 1.1, and the value of n is 1.8 to 2.2, and the fluorescent substance (A) and the Si-containing compound (B) are not the same.)

In this document, a compound represented by the following formula (2) is described as an example of the fluorescent substance (A).
_{(Ba 3-ab-3 xSr} a Ca b Eu 3x) MgSi 2 O 8 (2)
(In the formula, the value of a is in the range of 0 to less than 3, the value of b is in the range of 0 to less than 3, the value of x is in the range of 0.00016 to 0.1, and a + b + 3x ≦ 3)
Further, examples of Si-containing compound _{(B), SiO 2, MgSiO} 4, MgSiO oxides such _3, and 3-glycidoxypropyltrimethoxysilane, decyl trimethoxysilane, tetraethoxysilane, tetramethoxysilane, Organosilicon compounds having an alkoxyl group such as methyltrimethoxysilane, ethyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, dimethyldimethoxysilane, alkoxyl such as methyldimethoxyhydroxylsilane, methylmethoxydihydroxylsilane Having an organic silicon compound having a hydroxyl group such as trimethylsilanol, triethylsilanol and tripropylsilanol, and having a siloxane group such as octamethylcyclotetrasiloxane. Organosilicon compounds are described that.

  On the other hand, in Patent Document 2, polydimethylsiloxane having silanol groups at both ends or one end and a metal and / or metalloid alkoxide oligomer are subjected to a condensation reaction involving hydrolysis to form both ends of the polydimethylsiloxane. Or the organic-inorganic hybrid prepolymer which introduce | transduced the said metal and / or metalloid alkoxide in one terminal is described. This document describes adhesives and paints as uses of the organic-inorganic hybrid prepolymer.

JP 2007-224262 A International Publication No. 2011/125832

A phosphor used for a white LED of a three-color mixed type that combines a semiconductor light emitting element that emits light with a wavelength of 350 to 430 nm and three kinds of phosphors of a blue light emitting phosphor, a green light emitting phosphor, and a red light emitting phosphor, It is preferable that the emission intensity when excited with light having a wavelength of 350 to 430 nm is high and the high emission intensity is stably maintained over a long period of time.
Accordingly, an object of the present invention is to provide a phosphor exhibiting high emission intensity when excited with light having a wavelength of 350 to 430 nm and low emission over a long period of time.

  The inventor of the present invention uses a hydrolyzate of a prepolymer generated by a condensation reaction of a polydimethylsiloxane having a silanol group at at least one terminal and an oligomer of a metal and / or a metalloid alkoxide, to thereby improve the surface of the phosphor particles. The coated phosphor particles that are at least partially coated have the same emission intensity when excited with light having a wavelength of 350 to 430 nm as compared to the phosphor particles before coating, and decrease over a long period of time. Was found to show less luminescence, and the present invention was completed.

  Accordingly, the present invention provides a surface of a phosphor particle using a hydrolyzate of a prepolymer produced by a condensation reaction between a polydimethylsiloxane having a silanol group at at least one end and an oligomer of a metal and / or metalloid alkoxide. The coated phosphor particles are coated with at least a part thereof.

Preferred embodiments of the coated phosphor particles of the present invention are as follows.
(1) The metal and / or metalloid alkoxide is alkoxysilane.
(2) The hydrolyzate covers a region of 30% or more of the particle surface.
(3) The hydrolyzate is a hydrolyzate produced by hydrolysis of the prepolymer in the presence of water containing the prepolymer hydrolysis reaction accelerator.
(4) The phosphor particles have a hydroxyl group on the particle surface, and the hydrolyzate is bonded to the phosphor particles by condensation with at least a part of the hydroxyl groups on the particle surface.
(5) The phosphor particles are silicate phosphor particles.
(6) The silicate phosphor is a silicate phosphor represented by the following composition formula (I).
M ₃ MgSi ₂ O ₈ : Eu (1)
In formula (I), M represents one or two or more alkaline earth metals selected from the group consisting of Ca, Sr and Ba, or a mixture of the alkaline earth metal and rare earth metal.

  The present invention also provides phosphor particles, an organic solvent containing a prepolymer formed by a condensation reaction of a polydimethylsiloxane having a silanol group at least on one end and an oligomer of a metal and / or metalloid alkoxide, There is also a method for producing the coated phosphor particles of the present invention, including a step of mixing water containing a polymer hydrolysis reaction accelerator to hydrolyze the prepolymer.

  The coated phosphor particles of the present invention have high light emission intensity when excited with light having a wavelength of 350 to 430 nm, and the light emission does not substantially decrease over a long period of time. For this reason, the coated phosphor particle of the present invention is a combination of three types of phosphors: a semiconductor light emitting element that emits light having a wavelength of 350 to 430 nm, and a blue light emitting phosphor, a green light emitting phosphor, and a red light emitting phosphor. It can be advantageously used as a phosphor for a color mixed type white LED.

It is sectional drawing which shows an example of a structure of LED using the covering fluorescent substance particle of this invention.

  The coated phosphor particle of the present invention is a prepolymer in which at least a part of the particle surface is formed by a condensation reaction of polydimethylsiloxane having a silanol group at at least one end thereof and a metal and / or metalloid alkoxide oligomer. It is covered with a hydrolyzate. The area of the surface of the phosphor particles covered with the prepolymer hydrolyzate is preferably covered by 30% or more of the entire surface of the phosphor particles, and is in the range of 40 to 100%. It is particularly preferred that the region is covered. The region covered with the hydrolyzate on the surface of the phosphor particles can be confirmed by SEM (scanning electron microscope).

  The prepolymer used in the present invention is sometimes referred to as an organic-inorganic hybrid prepolymer. The prepolymer used in the present invention can be produced by the method described in Patent Document 2 (International Publication No. 2011/125832).

  In the prepolymer used in the present invention, the metal and / or metalloid alkoxide is preferably a silicon alkoxide (alkoxysilane).

  In the present invention, the phosphor particles before being coated with the prepolymer hydrolyzate preferably have a hydroxyl group on the particle surface. The prepolymer hydrolyzate covering the coated phosphor particles is preferably bonded to the phosphor particles by condensation with hydroxyl groups on the particle surfaces of the phosphor particles. In addition, the hydrolyzate of the prepolymer which coat | covers the surface of fluorescent substance particles may condense, and the polymer may be produced | generated.

Examples of phosphor particles having a hydroxyl group on the particle surface include silicate phosphor particles based on silicate. The silicate phosphor particles preferably have a hydroxyl group bonded to a silicon atom (+ tetravalent) on the particle surface. Examples of silicate phosphor particles include: (Ba, Sr, Ca) ₂ SiO ₄ : Blue emitting phosphor particles represented by a composition formula of (Ba, Sr, Ca) ₃ MgSi ₂ O ₈ : Eu: There may be mentioned green light emitting phosphor particles represented by a composition formula of Eu and red light emitting phosphor particles represented by a composition formula of (Ba, Sr, Ca) ₃ MgSi ₂ O ₈ : Eu, Mn. . These silicate phosphor particles may be added with rare earth elements such as Sc, Y, Gd, Tb and La. Examples of phosphor particles other than silicate phosphor particles include (Ba, Sr, Ca) MgAl ₁₀ O ₁₇ : Eu, (Ba, Sr, Mg, Ca) ₁₀ (PO ₄ ) ₆ (Cl, F) ₂ : Blue emitting phosphor particles represented by a composition formula such as Eu, BaMgAl ₁₀ O ₁₇ : Eu, Mn, α-SiAlON: Eu, β-SiAlON: Eu, ZnS: Cu, Al, etc. Particles of green light emitting phosphor, and Y ₂ O ₂ S: Eu, La ₂ O ₃ S: Eu, (Ca, Sr, Ba) ₂ Si ₅ N ₈ : Eu, CaAlSiN ₃ : Eu, Eu ₂ W ₂ Red light emitting phosphors represented by composition formulas such as O ₉ , (Ca, Sr, Ba) ₂ Si ₅ N ₈ : Eu, Mn, CaTiO ₃ : Pr, Bi, (La, Eu) ₂ W ₃ O ₁₂ Particles can be mentioned.

The blue light emitting phosphor particles are preferably silicate phosphors represented by the following composition formula (I).
M ₃ MgSi ₂ O ₈ : Eu (1)
In formula (I), M represents one or two or more alkaline earth metals selected from the group consisting of Ca, Sr and Ba, or a mixture of the alkaline earth metal and rare earth metal.

  The coated phosphor particles of the present invention are organic particles comprising phosphor particles and a prepolymer formed by a condensation reaction of polydimethylsiloxane having a silanol group at at least one end thereof and an oligomer of a metal and / or metalloid alkoxide. It can be produced by mixing a solvent and water containing a prepolymer hydrolysis reaction accelerator, hydrolyzing the prepolymer, and coating the surface of the phosphor particles with the resulting hydrolyzate. The organic solvent is preferably an organic solvent having compatibility with water. Examples of organic solvents include alcohols and ketones. The alcohol is preferably a monohydric alcohol having 1 to 5 carbon atoms. Examples of ketones include acetone, methyl acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone and methyl isobutyl ketone. Examples of hydrolysis reaction accelerators include ammonia, stannous octoate, dibutyltin diacylate, dibutyltin di-2-ethylhexoate, sodium-O-phenylphenate and tetra (2-ethylhexosyl) titanate. Can do.

  The coated phosphor particles produced in the organic solvent by the above method can be recovered by a solid-liquid separation method such as filtration or decantation. The recovered coated phosphor particles are preferably heat treated at a temperature of 120 to 300 ° C. after washing and drying. The heat treatment is preferably performed in an atmosphere of a reducing gas or an inert gas. Examples of the reducing gas include ammonia gas, carbon monoxide gas, hydrogen sulfide gas, and sulfur dioxide gas. Examples of the inert gas include nitrogen gas and argon gas. The time for the heat treatment is generally in the range of 10 minutes to 10 hours.

Next, an LED (light emitting diode) using the coated phosphor particles of the present invention will be described with reference to FIG. 1 of the accompanying drawings.
FIG. 1 is a cross-sectional view of an example of an LED using the coated phosphor particles of the present invention. In FIG. 1, an LED includes a substrate 1, a semiconductor light emitting device 3 fixed on the substrate 1 with an adhesive 2, a pair of electrodes 4a and 4b formed on the substrate 1, a semiconductor light emitting device 3 and an electrode 4a. 4b, lead wires 5a and 5b electrically connecting the semiconductor light emitting element 3, a resin layer 6 covering the semiconductor light emitting element 3, a phosphor layer 7 provided on the resin layer 6, and the resin layer 6 and the phosphor layer 7 The light reflecting material 8 that covers the periphery, and conductive wires 9a and 9b that electrically connect the electrodes 4a and 4b to an external power source (not shown). The semiconductor light emitting element 3 is preferably a semiconductor light emitting element that emits light having a wavelength of 350 to 430 nm by application of electric energy. As an example of the semiconductor light emitting device, an AlGaN semiconductor device can be cited. The phosphor layer 7 is formed of a transparent material in which the coated phosphor particles of the present invention are dispersed. The coated phosphor particles are preferably a mixture of three types of coated phosphor particles: coated blue light emitting phosphor particles, coated green light emitting phosphor particles, and coated red light emitting phosphor particles. Examples of the transparent material include transparent resins such as glass and silicone resin.

  In the LED of FIG. 1, when a voltage is applied to the electrodes 4a and 4b through the conductive wires 9a and 9b to apply electric energy to the semiconductor light emitting element 3, the semiconductor light emitting element 3 emits light and emitted light is generated. Visible light is generated by exciting the coated phosphor particles in the phosphor layer 7 with the emitted light of the semiconductor light emitting element 3. A semiconductor light-emitting element that emits light having a wavelength of 350 to 430 nm by applying electric energy is used as the semiconductor light-emitting element 3, and the coated blue-emitting phosphor particles, the coated green-emitting phosphor particles, and the coated phosphor particles in the phosphor layer 7 are used. By using three types of coated phosphor particles of the coated red light-emitting phosphor particles, white light generated from a mixture of blue light, green light and red light generated from these phosphors can be obtained.

[Example 1]
In an eggplant-shaped flask, a prepolymer (organic produced by a condensation reaction of a polydimethylsiloxane having a silanol group at at least one end produced by the method described in International Publication No. 2011-125842 and an oligomer of alkoxysilane was formed. -Inorganic hybrid prepolymer ( _1.452 g), silicate blue light emitting phosphor particles (Sr _2.955 Y _0.005 MgSi ₂ O ₈ : Eu _0.04 particles) 12 g, ethanol 60 mL, and a rotator were _charged and the rotator was rotated. Stir. While continuing stirring at room temperature, 2.616 g of an aqueous ammonia solution having a concentration of 25% by mass was slowly added dropwise to the eggplant flask over 10 minutes. After completion of the dropwise addition of the aqueous ammonia solution, stirring was further continued for 2 hours to hydrolyze the prepolymer, and the surface of the silicate blue light-emitting phosphor particles was coated with the hydrolyzate. The coated silicate blue emitting phosphor particles were then collected by filtration. The recovered coated silicate blue light-emitting phosphor particles were washed with methanol and then dried under reduced pressure overnight at a temperature of 60 ° C. using a vacuum dryer. The coated silicate blue light-emitting phosphor particles after drying were placed in a boron nitride (BN) crucible and placed in an annular furnace. The coated silicate blue light-emitting phosphor particles were heated at a temperature of 180 ° C. for 1 hour while flowing ammonia gas through the annular furnace. When the surface of the coated silicate blue light-emitting phosphor particles after being allowed to cool was observed using an SEM (scanning electron microscope), about 40% of the surface of the silicate blue light-emitting phosphor particles was hydrolyzed with prepolymer. It was confirmed that it was covered with the decomposition product.

[Example 2]
A glass vial was charged with 0.726 g of prepolymer and 5 mL of an aqueous ethanol solution having a concentration of 2 mol / L, and the vial was covered, and then the vial was shaken for 10 minutes using a mix rotor. Next, the lid of the vial is opened, 5 g of silicate blue light emitting phosphor particles (Sr _2.955 Y _0.005 MgSi ₂ O ₈ : Eu _0.04 particles) are put into the vial, and the vial is _covered again. Using a rotor, the vial was shaken overnight to hydrolyze the prepolymer, and a mixture in which the silicate blue-emitting phosphor particles were dispersed in the hydrolyzate was obtained. Next, this mixture was dropped into pure water stirred by a rotor to obtain coated silicate blue-emitting phosphor particles coated with a prepolymer hydrolyzate. The coated silicate blue light-emitting phosphor particles precipitated in pure water were collected by filtration. The recovered coated silicate blue light-emitting phosphor particles were washed with methanol and then dried under reduced pressure overnight at a temperature of 60 ° C. using a vacuum dryer. The coated silicate blue light-emitting phosphor particles after drying were placed in a boron nitride crucible and placed in an annular furnace. The coated silicate blue light-emitting phosphor particles were heated at a temperature of 180 ° C. for 1 hour while flowing ammonia gas through the annular furnace. When the surface of the coated silicate blue light-emitting phosphor particles after cooling was observed using SEM, about 50% of the surface of the surface of the silicate blue light-emitting phosphor particles was covered with the prepolymer hydrolyzate. It was confirmed that

[Example 3]
The amount of the prepolymer was 1.452 g, the amount of the aqueous ethanol solution was 16 mL, and the mixture in which the silicate phosphor particles were dispersed in the hydrolyzate of the prepolymer was vibrated by applying ultrasonic waves. Silicate blue light-emitting phosphor particles coated with a prepolymer hydrolyzate were obtained in the same manner as in Example 2 except that it was dropped little by little into 300 mL of pure water. When the surface of the obtained coated silicate blue light-emitting phosphor particles was observed using SEM, about 45% of the surface of the surface of the silicate blue light-emitting phosphor particles was coated with the prepolymer hydrolyzate. It was confirmed that

[Comparative Example 1]
The same silicate blue light-emitting phosphor particles (Sr _2.955 Y _0.005 MgSi ₂ O ₈ : Eu _0.04 particles) used in Examples 1 to 3 were prepared as Comparative Example 1.

[Comparative Example 2]
Silicate blue light-emitting phosphor particles treated with a tetraethoxysilane hydrolyzate were produced in the same manner as in Example 1 except that 1.452 g of tetraethoxysilane was used instead of the prepolymer.

[Evaluation]
The coated silicate blue light-emitting phosphor particles obtained in Examples 1 to 3, the silicate blue light-emitting phosphor particles of Comparative Example 1 and the tetraethoxysilane hydrolyzate obtained in Comparative Example 2 were treated. Using the silicate blue light emitting phosphor particles, a blue LED chip was manufactured by the following method. Then, electric energy was supplied to the blue LED chip, and the emission intensity of blue light having a wavelength of 460 nm was measured. This emission intensity is shown in Table 1 as the initial emission intensity. The initial light emission intensity is a relative value with the initial light emission intensity of Comparative Example 1 as 100.
Further, the emission intensity of visible light having a wavelength of 460 nm was measured after 100 hours, 200 hours, and 500 hours from the start of supplying electric energy to the blue LED chip. The measured emission intensity is shown in Table 1 as the emission intensity after a predetermined time. The light emission intensity after the elapse of a predetermined time is a relative value with the initial light emission intensity of each example and comparative example as 100.

[Method for producing blue LED chip]
A semiconductor ultraviolet light emitting element (emission wavelength: 400 nm) was fixed with an adhesive on a glass substrate on which an electrode was formed. Next, a reflecting member was formed on the glass substrate so as to surround the semiconductor ultraviolet light emitting element. Subsequently, the electrode of the glass substrate and the electrode of the semiconductor ultraviolet light emitting element were connected by wire bonding. Thereafter, a phosphor particle-containing resin composition in which phosphor particles of the sample are dispersed in a thermosetting silicone resin in an amount of 15% by mass is poured into the space between the reflecting member and the semiconductor ultraviolet light emitting element, and the fluorescence The body particle-containing resin composition was heat-treated to cure the thermosetting silicone resin to obtain a blue LED chip.

初期発光強度：比較例１の初期発光強度を１００とした相対値である。
所定時間経過の発光強度：それぞれの実施例及び比較例の初期発光強度を１００とした相対値である。

Initial emission intensity: Relative value with the initial emission intensity of Comparative Example 1 as 100.
Luminous intensity after elapse of a predetermined time: Relative value with initial luminous intensity of each example and comparative example as 100.

  From the results of Table 1, the coated silicate blue-emitting phosphor particles coated with the prepolymer hydrolyzate according to the present invention (Examples 1 to 3) have initial emission intensity when excited with 400 nm ultraviolet light. Is the same 100 as the silicate blue light emitting phosphor particles before comparison (Comparative Example 1), and is treated with a conventional hydrolyzate of tetraethoxysilane (Comparative Example 2). It can be seen that the value is higher than that.

  In addition, from the results of Table 1, the coated silicate blue light-emitting phosphor particles (Examples 1 to 3) coated with the prepolymer hydrolyzate according to the present invention have an initial light emission intensity of a predetermined time. From this, it can be seen that the emission intensity is stable over a long period of time. On the other hand, the luminescence intensity of the silicate blue light-emitting phosphor particles (Comparative Example 1) before coating decreases with the passage of time.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Adhesive 3 Semiconductor light emitting element 4a, 4b Electrode 5a, 5b Lead wire 6 Resin layer 7 Phosphor layer 8 Light reflecting material 9a, 9b Conductive wire

Claims (8)

  At least a part of the surface of the phosphor particles is covered with a hydrolyzate of a prepolymer produced by a condensation reaction between a polydimethylsiloxane having a silanol group at at least one end and an oligomer of a metal and / or metalloid alkoxide. Coated phosphor particles obtained.   The coated phosphor particle according to claim 1, wherein the metal and / or metalloid alkoxide is an alkoxysilane.   The coated phosphor particle according to claim 1, wherein the hydrolyzate covers a region of 30% or more of the particle surface.   The coated phosphor particle according to claim 1, wherein the hydrolyzate is a hydrolyzate produced by hydrolysis of a prepolymer in the presence of water containing a hydrolysis accelerator for the prepolymer.   The coated phosphor particle according to claim 1, wherein the phosphor particle has a hydroxyl group on the particle surface, and the hydrolyzate is bonded to the phosphor particle by condensation with at least a part of the hydroxyl group on the particle surface.   The coated phosphor particle according to claim 1, wherein the phosphor particle is a silicate phosphor particle. The coated phosphor particle according to claim 6, wherein the silicate phosphor is a silicate phosphor represented by a composition formula of the following (I):
M ₃ MgSi ₂ O ₈ : Eu (1)
In formula (I), M represents one or two or more alkaline earth metals selected from the group consisting of Ca, Sr and Ba, or a mixture of the alkaline earth metal and rare earth metal.   Hydrolysis reaction of a prepolymer with phosphor particles, an organic solvent containing a prepolymer produced by a condensation reaction of a polydimethylsiloxane having a silanol group at at least one end thereof, and an oligomer of a metal and / or metalloid alkoxide The method for producing coated phosphor particles according to claim 1, comprising a step of hydrolyzing the prepolymer by mixing with water containing an accelerator.

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