US20070166543A1 - Metal oxide phosphor microparticle and process for producing the same; utilizing the same, dispersion liquid, fluorescence conversion membrane, method of separating metal oxide phosphor microparticle, fluorescent liquid, fluorescent paste, phosphor and process for producing the same; and fluorescence converter - Google Patents

Metal oxide phosphor microparticle and process for producing the same; utilizing the same, dispersion liquid, fluorescence conversion membrane, method of separating metal oxide phosphor microparticle, fluorescent liquid, fluorescent paste, phosphor and process for producing the same; and fluorescence converter Download PDF

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US20070166543A1
US20070166543A1 US10/587,631 US58763105A US2007166543A1 US 20070166543 A1 US20070166543 A1 US 20070166543A1 US 58763105 A US58763105 A US 58763105A US 2007166543 A1 US2007166543 A1 US 2007166543A1
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metal oxide
microfine particles
based phosphor
phosphor
fluorescent
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Tetsuhiko Isobe
Ryo Kasuya
Aya Kawano
Hitoshi Kuma
Junichi Katano
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Idemitsu Kosan Co Ltd
Keio University
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Idemitsu Kosan Co Ltd
Keio University
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Assigned to IDEMITSU KOSAN CO., LTD., KEIO UNIVERSITY reassignment IDEMITSU KOSAN CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ISOBE, TETSUHIKO, KASUYA, RYO, KATANO, JUNICHI, KAWANO, AYA, KUMA, HITOSHI
Priority to US12/546,162 priority Critical patent/US7883641B2/en
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7774—Aluminates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/30—Devices specially adapted for multicolour light emission
    • H10K59/38—Devices specially adapted for multicolour light emission comprising colour filters or colour changing media [CCM]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S977/00—Nanotechnology
    • Y10S977/70—Nanostructure
    • Y10S977/778—Nanostructure within specified host or matrix material, e.g. nanocomposite films
    • Y10S977/783—Organic host/matrix, e.g. lipid
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S977/00—Nanotechnology
    • Y10S977/70—Nanostructure
    • Y10S977/778—Nanostructure within specified host or matrix material, e.g. nanocomposite films
    • Y10S977/786—Fluidic host/matrix containing nanomaterials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
    • Y10T428/256—Heavy metal or aluminum or compound thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
    • Y10T428/2991—Coated

Definitions

  • the present invention relates to metal oxide-based phosphor microfine particles, and more particularly to metal oxide-based phosphor microfine particles having a small particle size as well as a high affinity to and a high a light emitted from a light source, a process for producing the metal oxide-based phosphor microfine particles, dispersions of the metal oxide-based phosphor microfine particles, fluorescent conversion films, a method of separating the metal oxide-based phosphor microfine particles, fluorescent liquids, fluorescent pastes, phosphors, a process for producing the phosphors, and fluorescent converters.
  • Fluorescent conversion films using a phosphor or fluorescent material which are capable of converting light emitted from a light source into light having a different wavelength have been extensively used in various application fields such as electronic displays.
  • organic electroluminescent devices having an organic electroluminescent material portion emitting blue light or bluish green light, and a phosphor portion absorbing the light emitted from the light-emitting layer and emitting a visible fluorescence having at least one color ranging from bluish green to red (e.g., refer to Japanese Patent Application Laid-open No. 152897/1991).
  • red color fluorescent conversion films obtained by dispersing a rhodium-based fluorescent pigment and a fluorescent pigment having an absorption band in a blue light range and being capable of inducing transfer or reabsorption of energy into the rhodium-based fluorescent pigment, in a light-transmitting medium (e.g., refer to Japanese Patent Application Laid-open No. 286033/1996).
  • organic fluorescent pigments having a cycloalkyl group and/or a heterocyclic ring as a steric hindrance group, for example, as disclosed in Japanese Patent Application Laid-open No. 44824/2000.
  • reaction-curable resins such as photocurable resins and heat-curable resins have been mainly used in view of achieving improvements in heat resistance or productivity of the fluorescent conversion films.
  • reactive components contained in the resins are reacted with the organic fluorescent pigments, resulting in decomposition of the pigments or change in structure of the films and, therefore, further deterioration in fluorescent properties thereof.
  • FIG. 16 there is shown the relationship between an absorbance and a fluorescence quantum yield of the fluorescent conversion film when varying a concentration of pigments contained in the film
  • the circle mark ( ⁇ ) indicates the fluorescent conversion film obtained by dispersing rhodamine 6G as an organic fluorescent pigment in a benzoguanamine resin
  • the triangle mark ( ⁇ ) indicates the fluorescent conversion film obtained by dispersing coumarin 6 as an organic fluorescent pigment in a benzoguanamine resin
  • the solid triangle mark ( ⁇ ) indicates the fluorescent conversion film obtained by dispersing coumarin 6 as an organic fluorescent pigment in a photocurable resin.
  • the rhodamine 6G-dispersed film was irradiated with light from a light source having a peak at 534 nm, whereas the coumarin 6-dispersed films were irradiated with light from a light source having a peak at 456 nm.
  • the abscissa axis represents an absorbance at the wavelength, whereas the ordinate axis represents a fluorescence quantum yield.
  • the fluorescence quantum yield of the film is as low as less than 50% in the range where the absorbance to the excited light is more than 1 even when using such pigments having a fluorescence quantum yield as high as 80% or more.
  • the fluorescence quantum yield of the film is as low as about 30%.
  • cerium-activated yttrium/aluminum/garnet-based phosphors are used as the inorganic phosphors, and the phosphors are dispersed in a thermoplastic resin sheet to form a fluorescent conversion film.
  • YAG:Ce phosphors cerium-activated yttrium/aluminum/garnet-based phosphors
  • the phosphors are dispersed in a thermoplastic resin sheet to form a fluorescent conversion film.
  • the resultant microfine particles have a particle size in the order of a micron meter.
  • a metal oxide-based phosphor by reacting at least one compound selected from the group consisting of carbonates, nitrates, hydroxides, sulfates, phosphates, borates, silicates, aluminates, carboxylates, halides and alkoxides of a metal element constituting a matrix and an activator of the phosphor with an oxy-carboxylic acid or a polyamino chelating agent to obtain a metal complex, polymerizing the metal complex with a polyol in a solvent to produce a complex polymer, and baking the complex polymer.
  • An object of the present invention is to provide metal oxide-based phosphor microfine particles which have a small particle size as well as a high affinity to and a high dispersibility in light-transmittable medium, are inhibited from scattering light emitted from a light source, and exhibit excellent water resistance, chemical resistance and heat resistance; a process for producing the metal oxide-based phosphor microfine particles; a dispersion of the metal oxide-based phosphor microfine particles; a fluorescent conversion film; a method of separating the metal oxide-based phosphor microfine particles; a fluorescent liquid; a fluorescent paste; a phosphor; a process for producing the phosphor; and a fluorescent converter.
  • the inventors have found that the above object can be achieved by using, as a fluorescent material, metal oxide-based phosphor microfine particles comprising a matrix crystal made of a metal oxide, a metal element doped as an emission center into the matrix crystal, and an organic group coordinated to a surface of the microfine particles.
  • the present invention has been accomplished on the basis of the above finding.
  • the present invention provides:
  • Metal oxide-based phosphor microfine particles comprising a matrix crystal made of a metal oxide and a metal element doped as an emission center into the matrix crystal, wherein said microfine particles are provided with an organic group coordinated to a surface thereof;
  • a dispersion of metal oxide-based phosphor microfine particles comprising:
  • the metal oxide-based phosphor microfine particles comprising a matrix crystal made of a metal oxide and a metal element doped as an emission center into the matrix crystal, wherein said microfine particles are provided with an organic group coordinated to a surface thereof which is formed by dissociating at least one of the functional groups from the organic compound;
  • a fluorescent conversion film comprising a light-transmittable resin and the metal oxide-based phosphor microfine particles as defined above which are dispersed in the light-transmittable resin;
  • a process for producing metal oxide-based phosphor microfine particles comprising:
  • a method of separating metal oxide-based phosphor microfine particles comprising the step of subjecting a mixture of the metal oxide-based phosphor microfine particles and a solvent to centrifugal separation, filtration, natural sedimentation or combination thereof for classifying the microfine particles to separate transparent metal oxide-based phosphor microfine particles containing the solvent from the mixture;
  • a transparent fluorescent liquid comprising a solvent and 10% by weight or more of the metal oxide-based phosphor microfine particles as defined above, wherein light emitted from the metal oxide-based phosphor microfine particles which has a wavelength attributed to the metal oxide contained therein is transmitted through the fluorescent liquid at a transmittance of 50% or more in terms of an optical path length of 1 cm;
  • a transparent fluorescent paste comprising a solvent and 50% by weight or more of the metal oxide-based phosphor microfine particles as defined above, wherein light emitted from the metal oxide-based phosphor microfine particles which has a wavelength attributed to the metal oxide contained therein is transmitted through the fluorescent paste at a transmittance of 50% or more in terms of an optical path length of 150 ⁇ m;
  • a process for producing a phosphor comprising the step of baking the fluorescent liquid or the fluorescent paste as defined above at a temperature of 500° C. or lower;
  • a fluorescent converter comprising the phosphor as defined above solely, or a product obtained by adding a resin or a solvent to the phosphor and solidifying the obtained mixture, and a fluorescent converter obtained by dispersing the phosphor in a resin or a solvent.
  • the metal oxide-based phosphor microfine particles of the present invention have a small particle size as well as a high affinity to and a high dispersibility in light-transmittable resins, and exhibit excellent water resistance, chemical resistance and heat resistance. Therefore, a fluorescent conversion film, a fluorescent liquid, a fluorescent paste, a phosphor and a fluorescent converter using the metal oxide-based phosphor microfine particles are inhibited from scattering light emitted from a light source, and are extremely practical and useful for emitting a fluorescence by converting an excited light emitted from the light source into light having a longer wavelength when disposed on the light source.
  • FIG. 1 is an explanatory view showing a structure of metal oxide-based phosphor microfine particles of the present invention.
  • FIG. 2 is an explanatory view showing a surface condition of metal oxide-based phosphor microfine particles of the present invention.
  • FIG. 3 is an explanatory view showing a dispersion of metal oxide-based phosphor microfine particles of the present invention.
  • FIG. 4 is an explanatory view showing a function of a fluorescent conversion film of the present invention.
  • FIG. 5 is an explanatory view showing a process for producing metal oxide-based phosphor microfine particles according to the present invention.
  • FIG. 6 is another explanatory view showing a process for producing metal oxide-based phosphor microfine particles according to the present invention.
  • FIG. 7 is a view showing an X-ray diffraction pattern of particles obtained in Example 1 (upper portion) and a JCPDS card corresponding to Y 3 Al 5 O 12 (lower portion).
  • FIG. 8 is view showing an excitation spectrum and a fluorescence spectrum of particles obtained in Example 1.
  • FIG. 9 is a view showing an emission spectrum of an organic EL device obtained in Example 6 and an emission spectrum of light transmitted through a fluorescent conversion film.
  • FIG. 10 is a view showing an X-ray diffraction pattern of particles obtained in Comparative Example 1 (upper portion) and a JCPDS card corresponding to Y 3 Al 5 O 12 (lower portion).
  • FIG. 11 is a schematic view showing a thin film-shaped sample obtained in Example 9.
  • FIG. 12 is a photograph of the thin film-shaped sample obtained in Example 9 when viewed from above.
  • FIG. 13 is a view showing a transmission spectrum of a paste obtained in Example 9.
  • FIG. 14 is a view showing an excitation spectrum and a fluorescence spectrum of the paste obtained in Example 9.
  • FIG. 15 is a view showing the relationship between a film thickness and a fluorescence intensity with respect to pastes obtained in Example 16 and Comparative Example 3.
  • FIG. 16 is a view showing the relationship between an absorbance and a fluorescence quantum yield when varying a concentration of pigment contained in the conventional fluorescent conversion film.
  • the metal oxide-based phosphor microfine particles of the present invention include a matrix crystal made of a metal oxide and a metal element doped as an emission center into the matrix crystal, wherein said microfine particles are provided with an organic group coordinated to a surface thereof, as shown in FIG. 1 .
  • the organic group is derived from an organic compound having one or more functional groups at a terminal end or a side chain thereof by dissociating at least one of the function groups from the organic compound.
  • the organic group is coordinated to a metal atom or an oxygen atom of the metal oxide in the matrix crystal.
  • a functional group X is dissociated from an organic compound (X—R), and the resultant organic group R is coordinated to the oxygen atom.
  • Me represents a metal atom
  • O represents an oxygen atom.
  • the matrix crystal is preferably made of one or more kinds of metal oxides.
  • the metal oxides include BO 3 , B 4 O 12 , BaAl 8 O 13 , BaAl 12 O 19 , BaB 5 O 9 Br, BaMgAl 10 O 17 , BaMgAl 14 O 23 , BaGdNbO 5 , BaSi 2 O 5 , BaSO 4 , BeAl 2 O 4 , CaAl 12 O 19 , CaAl 2 O 3 , CaMgSi 2 O 7 , CaO, CaSiO 3 , CaWO 4 , Cd 2 B 2 O 5 , CeMgAl 11 O 19 , GdBO 3 , Gd 3 Ga 5 O 12 , GdMgB 5 O 10 , Gd 2 O 2 S, Gd 2 SiO 5 , Gd 2 (MoO 4 ) 3 , InBO 3 , LaBO 3 , La 2 O 2 S, LaOBr, LaOCl, Mg 6 As 2 O 11 , M
  • Y 3 Al 5 O 12 (Y x Gd 1-x ) 3 Al 5 O 12 , Y 3 (Al x Ga 1-x ) 5 O 12 , Y 2 O 3 and (Y x Gd 1-x ) 2 O 3 .
  • the formula “(Y x Gd 1-x ) 3 Al 5 O 12 ” means that (1-x) % by atom of yttrium (Y) in the crystal lattice of Y 3 Al 5 O 12 is replaced with gadolinium (Gd).
  • the metal element as an emission center is added as an impurity in the form of a metal atom or an ion into the metal oxide in the matrix crystal, and is present in the form of a solid solution in the matrix crystal.
  • the metal element is transferred to an excited state by absorbing light emitted from an excitation light source, and emits light when the excited state is deactivated and returned to its ground state.
  • Examples of the metal element as the emission center include the following elements:
  • A Metal elements belonging to Groups II, III, IV, V and VI of the Periodic Table: antimony ion (Sb 3+ ), tin ion (Sn 2+ ), lead ion (Pb 2+ ), thallium ion (Tl + ) and mercury atom (Hg);
  • Transition metal elements manganese ion (Mn 2+ , Mn 4+ ) and chromium ion (Cr 3+ );
  • rare earth metal element ions preferred are rare earth metal element ions, and more preferred is at least one element selected from the group consisting of europium (Eu), terbium (Th), praseodymium (Pr), cerium (Ce), samarium (Sm), thulium (Tm), dysprosium (Dy) and lutetium (Lu) in view of a high emission efficiency thereof.
  • Eu europium
  • Th terbium
  • Pr praseodymium
  • Ce cerium
  • Sm samarium
  • Tm thulium
  • Dy dysprosium
  • Lu lutetium
  • a suitable combination of the metal element of the metal oxide in the above matrix crystal and the metal element as the emission center includes, for example, such a combination in which the metal element of the metal oxide in the matrix crystal is at least one element selected from the group consisting of yttrium (Y), aluminum (Al), gadolinium (Gd), lanthanum (La), gallium (Ga) and barium (Ba), and the metal element as the emission center is at least one element selected from the group consisting of europium (Eu), cerium (Ce) and terbium (Tb).
  • Specific examples of compounds obtained by using the suitable combination of these metal elements in which europium (Eu) is used as the metal element as the emission center include BaAl 8 O 13 :Eu 2+ , BaMgM 10 O 17 :Eu 2+ , BaMgAl 14 O 23 :Eu 2+ , Y 2 O 3 :Eu 2+ , Ba 2 GdNbO 5 :Eu 3+ , BaMgAl 10 O 17 :Eu 3+ , BaMg 2 Al 16 O 27 :Eu 3+ , GdBO 3 :Eu 3+ , LuBO 3 :Eu 3+ , Y 3 Al 5 O 12 :Eu 3+ , YBO 3 :Eu 3+ , (Y x Gd 1-x ) 2 O 3 :Eu 3+ , Y 2 O 2 S:Eu 3+ and Y 2 O 3 :Eu 3+ .
  • terbium (Tb) is used as the metal element as the emission center
  • the organic group is obtained from an organic compound having one or more functional groups bonded to a terminal end or a side chain thereof by dissociating at least one of the functional groups from the organic compound.
  • Examples of the organic group include a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 50 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms and a substituted or unsubstituted aryloxy group having 5 to 50 carbon atoms.
  • substituted or unsubstituted alkyl group examples include methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 2-hydroxyisobutyl, 1,2-dihydroxyethyl, 1,3-dihydroxyisopropyl, 2,3-dihydroxy-t-butyl, 1,2,3-trihydroxypropyl, chloromethyl, 1-chloroethyl, 2-chloroethyl, 2-chloroisobutyl, 1,2-dichloroethyl, 1,3-dichloroisopropyl, 2,3-dichloro-t-butyl, 1,2,3-trichloropropyl, bromomethyl,
  • substituted or unsubstituted alkenyl group examples include vinyl, allyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butanedienyl, 1-methylvinyl, stearyl, 2,2-diphenylvinyl, 1,2-diphenylvinyl, 1-methylallyl, 1,1-dimethylallyl, 2-methylallyl, 1-phenylallyl, 2-phenylallyl, 3-phenylallyl, 3,3-diphenylallyl, 1,2-dimethylallyl, 1-phenyl-1-butenyl and 3-phenyl-1-butenyl.
  • alkenyl groups preferred are stearyl, 2,2-diphenylvinyl and 1,2-diphenylvinyl.
  • the substituted or unsubstituted alkoxy group may be groups represented by the formula: —OY.
  • Y group include those alkyl groups as specifically exemplified above.
  • substituted or unsubstituted cycloalkyl group examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 1-adamantyl, 2-adamantyl, 1-norbornyl and 2-norbornyl.
  • substituted or unsubstituted aryl group examples include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenathryl, 2-phenathryl, 3-phenathryl, 4-phenathryl, 9-phenathryl, 1-naphthacenyl, 2-naphthacenyl, 9-naphthacenyl, 1-pyrenyl, 2-pyrenyl, 4-pyrenyl, 2-biphenylyl, 3-biphenylyl, 4-biphenylyl, p-terphenyl-4-yl, p-terphenyl-3-yl, p-terphenyl-2-yl, m-terphenyl-4-yl, m-terphenyl-3-yl, m-terphenyl-2-yl, o-tolyl, m-tolyl, p-tolyl,
  • substituted or unsubstituted heteroaryl group examples include 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, pyrazinyl, 2-pyridinyl, 3-pyridinyl, 4-pyridinyl, 1-indolyl, 2-indolyl, 3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl, 7-indolyl, 1-isoindolyl, 2-isoindolyl, 3-isoindolyl, 4-isoindolyl, 5-isoindolyl, 6-isoindolyl, 7-isoindolyl, 2-furyl, 3-furyl, 2-benzofuranyl, 3-benzofuranyl, 4-benzofuranyl, 5-benzofuranyl, 6-benzofuranyl, 7-benzofuranyl, 1-isobenzofuranyl, 3-isobenzofuranyl, 4-isobenzofuranyl
  • substituted or unsubstituted aralkyl group examples include benzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylisopropyl, 2-phenylisopropyl, phenyl-t-butyl, ⁇ -naphthylmethyl, 1- ⁇ -naphthylethyl, 2- ⁇ -naphthylethyl, 1- ⁇ -naphthylisopropyl, 2- ⁇ -naphthylisopropyl, ⁇ -naphthylmethyl, 1- ⁇ -naphthylethyl, 2- ⁇ -naphthylethyl, 1- ⁇ -naphthylisopropyl, 2- ⁇ -naphthylisopropyl, 1-pyrrolylmethyl, 2-(1-pyrrolyl)ethyl, p-methylbenzyl, m-methylbenzyl, o
  • the substituted or unsubstituted aryloxy group is represented by the formula: —OY′.
  • Y′ group include those aryl groups as specifically exemplified above.
  • the respective groups as specifically exemplified above are in the form of a monovalent group, there may also be used di- or more valent groups formed by further dissociating one or more hydrogen atoms therefrom as well as those group obtained by substituting the hydrogen atoms with the following functional groups.
  • the metal oxide-based phosphor microfine particles of the present invention have an average particle size as small as 1 to 100 nm and preferably 1 to 60 nm.
  • Examples of the functional groups include those groups having at least one proton which are represented by the formula: ZH n wherein Z is an element belonging to Group 15 or 16 of the Periodic Table; and n is an integer of 1 or more.
  • these functional groups preferred are OH; NH 2 , SH and NHR′ wherein R′ is an alkyl group, and more preferred is OH.
  • Examples of the organic compound having one or more functional groups at a terminal end or a side chain thereof include isobutyl alcohol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerol, ethylene glycol, trimethylene glycol, 1,3-propanediol, 1,4-hydroxybenzene, 1,3-hydroxybenzene, 1,2-hydroxybenzene, 2-hydroxyehylmercaptan and 2-hydroxyethylamine.
  • preferred are 1,4-butanediol, glycerol and ethylene glycol.
  • the coordination of the above organic group to a surface of the metal oxide-based phosphor microfine particles of the present invention may be determined by TG-DTA (thermogravimetric differential thermal analysis) method or the like.
  • TG-DTA thermogravimetric differential thermal analysis
  • the coordination of an organic group “(CH 2 ) 4 OH” formed by dissociating a terminal OH group from 1,4-butanediol “OH(CH 2 ) 4 OH” to the surface of the respective microfine particles may be determined by continuous reduction in weight of the microfine particles which is observed when the microfine particles are continuously heated beyond a boiling point (229° C.) of 1,4-butanediol.
  • the metal oxide-based phosphor microfine particles having the organic group coordinated to the surface thereof are continuously heated, the weight thereof is continouously reduced owing to thermal decomposition of the organic group.
  • the dispersion of the metal oxide-based phosphor microfine particles according to the present invention is constituted from, as shown in FIG. 3 , (a) a dispersing medium containing an organic compound having one or more functional groups bonded to a terminal end or a side chain thereof; and (b) the metal oxide-based phosphor microfine particles comprising a matrix crystal made of a metal oxide and a metal element doped as an emission center into the matrix crystal, wherein said microfine particles are provided with an organic group coordinated to a surface thereof which is formed by dissociating at least one of the functional groups from the organic compound.
  • the dispersion of the metal oxide-based phosphor microfine particles according to the present invention contains the metal oxide-based phosphor microfine particles of the present invention as the component (b), and the dispersing medium containing the same kind of organic compound as used in the component (b) and, therefore, can exhibit a very good dispersibility.
  • the dispersing medium as the component. (a) may also contain, in addition to the above organic compound, other known components.
  • the other known components include ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve and cellosolve acetate; lactones such as ⁇ -butyrolactone; and polyethylene glycol.
  • the dispersion of the metal oxide-based phosphor microfine particles according to the present invention may further contain (c) a resin component.
  • the resin component examples include non-curable-type resins, heat-curable resins and photocurable resins.
  • Specific examples of the resin component include oligomers or polymers such as melamine resins, phenol resins, alkyd resins, epoxy resins, polyurethane resins, maleic acid resins, polyamide resins, polymethyl methacrylate, polyallylates, polycarbonates, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose and carboxymethyl cellulose, and copolymers containing constitutional monomers of these oligomers or polymers.
  • photocurable resin components there may be used photocurable resin components.
  • the photocurable resin there may be used reactive vinyl group-containing photopolymerizable resins such as acrylic acid-based or methacrylic acid-based resins and methacrylic ester-methacrylic acid copolymers, which usually contain a photosensitive agent; and photo-crosslinkable resins such as polyvinyl cinnamate.
  • the photocurable resins may also contain, if required, monomers and/or oligomers having a photopolymerizable ethylenically unsaturated group, a photopolymerization initiator or a sensitizer.
  • hydroxyl-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and 2-hydroxyhexyl (meth)acrylate
  • (meth)acrylic esters such as ethylene glycol (meth)acrylate and diethylene glycol (meth)acrylate.
  • Suitable photopolymerization initiator or sensitizer examples include acetophenones, benzophenones, benzoin ethers, sulfur compounds, anthraquinones, organic peroxides and thiols.
  • a light-transmittable resin is preferably used as the resin component (c).
  • the light-transmittable resin means such a resin capable of transmitting light emitted from an excitation light source or a phosphor at a transmittance of 30% or more. Examples of such a light-transmittable resin include those resin components as specifically exemplified above.
  • the dispersion of the metal oxide-based phosphor microfine particles according to the present invention may also contain, if required, various additives such as curing accelerators, thermal polymerization inhibitors, plasticizers, defoaming agents and leveling agents.
  • curing accelerators include perbenzoic acid derivatives, peracetic acid and benzophenones.
  • thermal polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, pyrogallol, t-butyl catechol and phenothiazine.
  • specific examples of the plasticizers include dibutyl phthalate, dioctyl phthalate and tricresyl.
  • the fluorescent conversion film of the present invention is constituted of a light-transmittable resin and the metal oxide-based phosphor microfine particles of the present invention which are dispersed in the light-transmittable resin, as shown in FIG. 4 .
  • Examples of the light-transmittable resin include those resins as exemplified above.
  • the method of producing the fluorescent conversion film is not particularly limited.
  • the fluorescent conversion film may be produced by applying a dispersion obtained by mixing the metal oxide-based phosphor microfine particles of the present invention, the dispersing medium and the light-transmittable resin with each other onto s substrate by a known film-forming method such as spin-coating, screen-coating, dip-coating and inkjetting. After completion of forming the film, the resultant film may be appropriately heated depending upon a boiling point of the dispersing medium, a vapor pressure and a thickness of the film to evaporate the dispersing medium from the film, thereby obtaining the fluorescent conversion film containing the metal oxide-based phosphor microfine particles dispersed in the light-transmittable resin.
  • the thickness of the thus obtained fluorescent conversion film is usually from 0.1 ⁇ m to 1 mm and preferably from 1 ⁇ m to 100 ⁇ m.
  • the content of the metal oxide-based phosphor microfine particles in the fluorescent conversion film is usually from 0.1 to 90% by mass and preferably from 1 to 70% by mass.
  • the resultant fluorescent conversion film is capable of fully absorbing light emitted from an excitation light source, resulting in a large intensity of the finally obtained fluorescence.
  • the content of the metal oxide-based phosphor microfine particles is 90% by mass or less, the resultant fluorescent conversion film can exhibit a good smoothness and a high mechanical strength.
  • the fluorescent conversion film, the fluorescent liquid, the fluorescent paste, the phosphor and the fluorescent converter according to the present invention are functioned as follows.
  • the fluorescent conversion film is disposed on an excitation light source, and allow excited light emitted from the excitation light source to pass therethrough such that the light passed therethrough is converted into light having a longer wavelength (e.g., blue light is converted into green or red light), thereby generating a fluorescence.
  • the excitation light source include organic electroluminescent devices, inorganic electroluminescent devices, light-emitting diodes, cold cathode tubes, fluorescent tubes and lasers. Among these light sources, preferred are organic electroluminescent devices and light-emitting diodes.
  • the process for producing the metal oxide-based phosphor microfine particles includes, as shown in FIG. 5 , a compound of a metal element forming a matrix made of a metal oxide and a compound of a metal element as an emission center are dissolved or dispersed in a dispersing medium containing an organic compound having one or more functional groups bonded to a terminal end or a side chain thereof to prepare a raw solution, and the thus prepared raw solution is enclosed in a pressure container and heated at a temperature not lower than a boiling point of the organic compound.
  • the production process generally includes the following three steps, i.e., (1) selection, blending and charging of raw materials (source of the matrix-forming metal oxide, source of the metal element as the emission center, the organic compound, and the dispersing medium); (2) heating; and (3) purification.
  • the respective steps are sequentially explained below.
  • Specific examples of supply sources of the metal element forming the matrix-forming metal oxide constituting the metal oxide-based phosphor microfine particles of the present invention and the metal element as the emission center include carbonates, acetates, nitrates, hydroxides, sulfates, phosphates, borates, silicates, aluminates, carboxylates, halides and alkoxides of the metal element forming the matrix-forming metal oxide and the metal oxide as the emission center as well as hydrates of these compounds. These compounds are blended with each other at a desired mixing ratio capable of producing the aimed compound by an ordinary method, and dissolved and dispersed in the above dispersing medium to prepare the raw solution. The thus prepared raw solution enclosed in a pressure container such as typically an autoclave.
  • dispersing medium containing an organic compound having one or more functional groups bonded to a terminal end or a side chain thereof there may be used those dispersing media as explained above with respect to the dispersion of the metal oxide-based phosphor microfine particles.
  • the mixing ratio of a sum of the compound of the metal element forming the matrix-forming metal oxide and the metal element as the emission center (metal compounds) to the dispersing medium may be determined depending upon a desired solid content in the finally obtained dispersion and uniformity of the raw materials.
  • the mixing ratio of the metal compounds to the dispersing medium is usually from 0.1:100 to 50:50 (mass ratio) and preferably from 1:99 to 50:50.
  • the proportion of the dispersing medium in the raw solution is not increased so that the pressure in the pressure container during the below-mentioned heating step is kept low, it is effective to adopt such a method as shown in FIG. 6 in which an inner tubular container filled with the raw solution prepared by mixing the respective components at a given mixing ratio is enclosed in the pressure container filled with the dispersing medium solely.
  • volume ratio of an inner capacity of the pressure container to the raw solution is preferably as large as possible in order to shorten the below-mentioned heating time. More specifically, the volume ratio is preferably 40% or more and more preferably 60% or more.
  • the reaction In order to accelerate the reaction of the raw solution, heat is supplied from an external heating source disposed outside of the pressure container.
  • the production of the metal oxide-based phosphor microfine particles requires baking at a high temperature such as usually 800° C. or higher.
  • the reaction can be conducted at a temperature as low as, for example, 200 to 500° C. since the reaction proceeds under a high-temperature condition.
  • the particles obtained by the process of the present invention have a smaller particle size than those obtained by ordinary conventional processes.
  • the heating temperature is not less than a boiling point of the dispersing medium used.
  • the reaction may be conducted under a pressure of usually 0.5 to 10 MPa and preferably 1 to 8 MPa.
  • the heating time may be appropriately determined because the pressure to be reached varies depending upon kind of aimed metal oxide-based phosphor microfine particles, raw compounds and kind of dispersing medium used, and is usually in the range of from 1 to 10 h.
  • the heating time is shorter than 1 h, the resultant microfine particles exhibit a low crystallinity, thereby failing to attain a sufficient fluorescence intensity.
  • the heating time is longer than 10 h, the resultant microfine particles tend to suffer from inclusion of impurities owing to carbonization of the dispersing medium or accelerated secondary agglomeration thereof.
  • the obtained reaction product is cooled to room temperature. If required, the reaction product is subjected to centrifugal separation, and the residual precipitate is mixed with an organic solvent and then subjected again to centrifugal separation.
  • the particles are baked at a high temperature such as 1000° C. or higher. In such a case, the particles tend to suffer from accelerated secondary agglomeration, so that the obtained fine particles have a particle size as large as 100 nm or more.
  • the resultant particles may be mixed with an organic solvent and repeatedly subjected to centrifugal separation plural times.
  • the method of separating metal oxide-based phosphor microfine particles according to the present invention includes the step of subjecting a mixture of the metal oxide-based phosphor microfine particles and a solvent to centrifugal separation, filtration, natural sedimentation or combination thereof for classifying the microfine particles to thereby separate transparent metal oxide-based phosphor microfine particles containing the solvent from the mixture.
  • the method of separating metal oxide-based phosphor microfine particles includes the steps of mixing a mixture of the metal oxide-based phosphor microfine particles and a solvent, with a solvent capable of varying a dispersing condition of the microfine particles; and subjecting the resultant mixture to centrifugal separation, filtration, natural sedimentation or combination thereof for classifying the microfine particles to thereby separate transparent metal oxide-based phosphor microfine particles containing the solvent from the mixture.
  • the solvent capable of varying a dispersing condition of the microfine particles there may be suitably used, for example, the solvents used for producing the metal oxide-based phosphor microfine particles below, or water.
  • These solvents can exhibit a function of varying the dispersing condition of the microfine particles.
  • the solvent used in synthesis of the phosphor for example, 1,4-butanediol
  • the ratio of the dispersed microfine particles to the solvent is varied, resulting in change in adsorption equilibrium and, therefore, change in dispersibility.
  • an organic solvent such as acetone
  • the dispersing condition of the microfine particles tends to become unstable, resulting in accelerated precipitation thereof.
  • Typical examples of the solvents capable of varying a dispersing condition of the microfine particles include linear or branched alcohols, monohydric alcohols, polyhydric alcohols, alkanes, ketones, ethers, esters, aromatic solvents and water.
  • the solvent may be appropriately added in an optimum amount in view of the dispersing condition of the microfine particles.
  • the fluorescent liquid of the present invention is a transparent fluorescent liquid which contains a solvent and 10% by weight or more of the metal oxide-based phosphor microfine particles of the present invention, wherein light emitted from the metal oxide-based phosphor microfine particles which has a wavelength attributed to a metal oxide contained therein is transmitted through the fluorescent liquid at a transmittance of 50% or more in terms of an optical path length of 1 cm.
  • the “fluorescent liquid” used herein generally means a liquid having a viscosity of 50,000 cp or less, in a narrow sense, a liquid having a viscosity of 1,000 cp or less.
  • the fluorescent paste of the present invention is a transparent fluorescent paste which contains a solvent and 50% by weight or more of the metal oxide-based phosphor microfine particles of the present invention, wherein light emitted from the metal oxide-based phosphor microfine particles which has a wavelength attributed to a metal oxide contained therein is transmitted through the fluorescent paste at a transmittance of 50% or more in terms of an optical path length of 150 ⁇ m.
  • the “fluorescent paste” used herein generally means a liquid having a viscosity of 1,000 cp or more, in a narrow sense, a liquid having a viscosity of 50,000 cp or more.
  • solvents used in the fluorescent liquid and the fluorescent paste include, in addition to 1,4-butanediol, linear or branched alcohols, monohydric alcohols, polyhydric alcohols, alkanes, ketones, ethers, esters, aromatic solvents and water.
  • the fluorescent liquid and the fluorescent paste are respectively baked at a temperature of 500° C. or lower to obtain a phosphor in the form of a transparent solid.
  • the baking atmosphere may be appropriately selected from air, an inert gas, etc.
  • the fluorescent converter of the present invention is composed of either the phosphor of the present invention solely or a product obtained by adding a resin and/or a solvent to the phosphor and solidifying the obtained mixture. Also, the fluorescent converter of the present invention is obtained by dispersing the phosphor of the present invention in a resin and/or a solvent.
  • the resin used in the fluorescent converter of the present invention is not particularly limited, and any suitable known resins may be used therefor.
  • Examples of the resin include the same resins as exemplified as the resin component (c).
  • the solvent used in the fluorescent converter is not particularly limited, and any suitable known solvents may be used therefor.
  • the resultant reaction product is cooled to room temperature. Then, a phosphor in the form of a mixture composed of the metal oxide-based phosphor microfine particles, the organic group coordinated to the surface of the respective metal oxide-based phosphor microfine particles and the solvent is separated from the reaction product. In this case, by selecting appropriate conditions, it is possible to separate a transparent phosphor.
  • the separation procedure may be performed in the following order. First, in order to facilitate the subsequent separation treatment, one to several kinds of the above solvents capable of varying a dispersing condition of the microfine particles are added to the reaction product. The amount of the solvents added is from 1/20 to 2/1 and preferably from 1/5 to 1/1 on the basis of the volume of the reaction product.
  • the obtained mixture may be subjected to accelerated mixing treatment using an ultrasonic homogenizer or a mechanical homogenizer.
  • an ultrasonic homogenizer or a mechanical homogenizer.
  • the phosphor can be readily separated from the reaction product in the subsequent separation treatment owing to the condition of the reaction product, it is not required to add the solvents thereto.
  • the reaction product is subjected to the first standing, the first filtration or the first centrifugal separation to remove coarse particles therefrom (classification).
  • the coarse particles to be removed include those particles having a particle size of usually 1 ⁇ m or more, preferably 0.1 ⁇ m or more and more preferably 0.01 ⁇ m or more.
  • the reaction product from which the coarse particles are removed is subjected to the second standing, the second filtration or the second centrifugal separation to remove classified microfine particles therefrom.
  • the first and second standing times may be respectively appropriately selected from the range of from one day to about one month depending upon the extent of production of the microfine particles.
  • the first and second filtration procedures may be performed by using any filter as long as the coarse and microfine particles are respectively suitably separated thereby, the filtration for the dispersion of the microfine particles is preferably conducted using a filter having a large filtering area, for example, a hollow fiber filter, a bobbin filter, a membrane cartridge filter or combination of a plurality of these filters.
  • the first and second centrifugal separation procedures may be performed under a centrifugal force of usually from 100 g to 100000 g and preferably from 1000 g to 5000 g for a treating time of usually from 10 min to 3 h and preferably from 30 min to 60 min.
  • the precipitate obtained after the centrifugal separation may be separated by decantation.
  • a transparent phosphor dispersion having a low solid content is produced in the vicinity of the solid-liquid interface.
  • the solvents capable of varying a dispersing condition of the microfine particles is added in the separation procedure, the solvents are removed under a nitrogen gas flow or by vacuum drying, if required.
  • the thus separated phosphor is present in a paste state. Further, the paste is baked at a temperature of usually 500° C. or lower, preferably 400° C. or lower and more preferably from 250 to 300° C., for example, under a nitrogen gas flow, to obtain a transparent phosphor (solid).
  • the baking time varies depending upon a total amount of the paste to be treated, and is suitably from about 10 min to about 1 h.
  • the resultant reaction product particles fixed on a glass substrate were used as a sample to measure an X-ray diffraction angle and diffraction intensity using an X-ray diffractometer “Rint 2200” available from Rigaku Denki Co., Ltd., thereby obtaining the relationship therebetween.
  • the identification of the obtained particles was conducted by comparing the results with JCPDS card (powder X-ray diffraction data base edited by JCPDS (Joint Commitee on Powder Diffraction Standards) of ICDD (International Center for Diffraction Data)).
  • sample solution On a platinum dish were placed 0.02 g of the resultant reaction product particles, and a mixed solvent composed of water, sulfuric acid and hydrochloric acid was added thereto to dissolve the particles in the mixed solvent, thereby obtaining a sample solution.
  • the sample solution was subjected to ICP emission spectral analysis to measure a mass percent of respective metal elements contained in the sample solution.
  • the resultant particles were filled in a quartz cell to measure a peak wavelength ⁇ Ex of an excitation spectrum thereof using a fluorescent spectrophotometer “FP-6500” available from Nippon Bunkko Co., Ltd. Next, a peak wavelength ⁇ EM and a peak intensity I of a fluorescence spectrum obtained by using ⁇ EX as an excitation wavelength, were measured.
  • a transmittance of the phosphor sample was measured using an ultraviolet/visible light spectrophotometer “UV3100” available from Shimadzu Seisakusho Co., Ltd.
  • UV3100 ultraviolet/visible light spectrophotometer
  • the thin film sample was grasped by a thin film holder to measure a transmittance to light being incident onto the substrate in the direction perpendicular thereto.
  • the solution sample was filled in a solution cell of 1 cm square to measure the transmittance.
  • a glass inner tube previously filled with 52.8 mL of 1,4-butanediol as a dispersing medium (hereinafter referred to merely as “1,4-BD”; available from Kanto Kagaku Co., Ltd.; boiling point: 229° C.) was charged with 2.51 g of yttrium acetate tetrahydrate available from Kanto Kagaku Co., Ltd., 0.025 g of cerium acetate monohydrate available from Kanto Kagaku Co., Ltd., and 2.55 g of aluminum triusopropoxide (hereinafter referred to merely as “AIP”) available from Kanto Kagaku Co., Ltd.
  • 1,4-BD 1,4-butanediol as a dispersing medium
  • the thus obtained particles were identified by X-ray diffraction using the above method (1).
  • FIG. 7 there are shown the obtained X-ray diffraction pattern (upper portion), and JCPDS card corresponding to Y 3 Al 5 O 12 (lower portion).
  • FIG. 7 it was confirmed that all of peaks including the peak at (420) plane having a strongest diffraction intensity were consistent with those of JCPDS card corresponding to Y 3 Al 5 O 12 , and a matrix crystal thereof was therefore composed of Y 3 Al 5 O 12 .
  • the content (% by mass) of Ce in the particles was measured by the above method (2). As a result, it was confirmed that the content of Ce was 0.53% by mass and, therefore, Ce was doped into the particles.
  • the average particle size of the particles was measured by the above method (3). As a result, it was confirmed that the average particle size of the particles was 46 nm.
  • the wavelengths ⁇ EX and ⁇ EM and the peak intensity I were measured by the above method (4). As a result, it was confirmed that the wavelengths ⁇ EX and ⁇ EM were 452 nm and 528 nm, respectively, and the peak intensity I was 25.9 (optional unit).
  • FIG. 8 there are shown an excitation spectrum and a fluorescence spectrum obtained from the measurement.
  • the content (% by mass) of Ce in the particles was measured by the above method (2). As a result, it was confirmed that the content of Ce was 0.54% by mass and, therefore, Ce was doped into the particles.
  • the average particle size of the particles was measured by the above method (3). As a result, it was confirmed that the average particle size of the particles was 52 nm.
  • the wavelengths ⁇ EX and ⁇ EM and the peak intensity I were measured by the above method (4). As a result, it was confirmed that the wavelengths ⁇ EX and ⁇ EM were 453 nm and 528 nm, respectively, and the peak intensity I was 38.3 (optional unit).
  • Example 3 Metal Oxide-Based Phosphor Microfine Particles: Y 3 M 5 O 12 :Ce, Lu
  • the contents (% by mass) of Ce and Lu in the particles were measured by the above method (2). As a result, it was confirmed that the content of Ce was 0.52% by mass, the content of Lu was 3.51% by mass and, therefore, Ce and Lu were doped into the particles.
  • the average particle size of the particles was measured by the above method (3). As a result, it was confirmed that the average particle size of the particles was 56 nm.
  • the wavelengths ⁇ EX and ⁇ EM and the peak intensity I were measured by the above method (4). As a result, it was confirmed that the wavelengths ⁇ EX and ⁇ EM were 452 nm and 526 nm, respectively, and the peak intensity I was 18.8 (optional unit).
  • Example 4 Metal Oxide-Based Phosphor Microfine Particles: Y 3 Al 5 O 12 :Ce
  • a glass inner tube previously filled with 52.8 mL of 1,4-BD as a dispersing medium was charged with 2.51 g of yttrium acetate tetrahydrate available from Kanto Kagaku Co., Ltd., 0.025 g of cerium acetate monohydrate available from Kanto Kagaku Co., Ltd., and 3.07 g of aluminum tri-sec-butoxide (hereinafter referred to merely as “ASB”) available from Kanto Kagaku Co., Ltd.
  • ASB aluminum tri-sec-butoxide
  • the content (% by mass) of Ce in the particles was measured by the above method (2). As a result, it was confirmed that the content of Ce was 0.46% by mass and, therefore, Ce was doped into the particles.
  • the average particle size of the particles was measured by the above method (3). As a result, it was confirmed that the average particle size of the particles was 82 nm.
  • the wavelengths ⁇ EX and ⁇ EM and the peak intensity I were measured by the above method (4). As a result, it was confirmed that the wavelengths ⁇ EX and ⁇ EM were 452 nm and 530 nm, respectively, and the peak intensity I was 15.8 (optional unit).
  • Example 5 Metal Oxide-Based Phosphor Microfine Particles: Y 3 Al 5 O 12 :Ce
  • a glass inner tube previously filled with 52.8 mL of ethylene glycol (hereinafter referred to merely as “EG”; available from Kanto Kagaku Co., Ltd.; boiling point: 198° C.) as a dispersing medium was charged with 2.51 g of yttrium acetate tetrahydrate available from Kanto Kagaku Co., Ltd., 0.025 g of cerium acetate monohydrate available from Kanto Kagaku Co., Ltd., and 2.55 g of AIP available from Kanto Kagaku Co., Ltd.
  • EG ethylene glycol
  • the content (% by mass) of Ce in the particles was measured by the above method (2). As a result, it was confirmed that the content of Ce was 0.52% by mass and, therefore, Ce was doped into the particles.
  • the average particle size of the particles was measured by the above method (3). As a result, it was confirmed that the average particle size of the particles was 51 nm.
  • the wavelengths ⁇ EX and ⁇ EM and the peak intensity I were measured by the above method (4). As a result, it was confirmed that the wavelengths ⁇ EX and ⁇ EM were 452 nm and 530 nm, respectively, and the peak intensity I was 15.8 (optional unit).
  • Example 6 Metal Oxide-Based Phosphor Microfine Particles: Y 3 Al 5 O 12 :Ce
  • the content (% by mass) of Ce in the particles was measured by the above method (2). As a result, it was confirmed that the content of Ce was 0.48% by mass and, therefore, Ce was doped into the particles.
  • the average particle size of the particles was measured by the above method (3). As a result, it was confirmed that the average particle size of the particles was 52 nm.
  • the wavelengths ⁇ EX and ⁇ EM and the peak intensity I were measured by the above method (4). As a result, it was confirmed that the wavelengths ⁇ EX and ⁇ EM were 452 nm and 528 nm, respectively, and the peak intensity I was 48.1 (optional unit).
  • Example 7 Metal Oxide-Based Phosphor Microfine Particles: Y 3 Al 5 O 12 :Ce
  • the content (% by mass) of Ce in the particles was measured by the above method (2). As a result, it was confirmed that the content of Ce was 0.55% by mass and, therefore, Ce was doped into the particles.
  • the average particle size of the particles was measured by the above method (3). As a result, it was confirmed that the average particle size of the particles was 104 nm.
  • the wavelengths ⁇ EX and ⁇ EM and the peak intensity I were measured by the above method (4). As a result, it was confirmed that the wavelengths ⁇ EX and ⁇ EM were 452 nm and 526 nm, respectively, and the peak intensity I was 37.1 (optional unit).
  • Methacrylic acid-methyl methacrylate copolymer (copolymerization ratio of methacrylic acid: 15%; weight-average molecular weight (Mw): 20000)
  • the thus obtained dispersion was applied onto a glass substrate by a screen printing method to form a coating film thereon.
  • the obtained coating film was dried at 150° C. for 20 min. Successively, the dried film was irradiated in air with light with an intensity of 300 mJ/cm 3 from a high-pressure mercury lamp, and then heat-treated in air at 200° C. for 60 min to obtain a fluorescent conversion film having a thickness of 10 ⁇ m.
  • a glass inner tube previously filled with 52.8 mL of 1-methoxy-2-acetoxypropane (hereinafter referred to merely as “PGMEA”; available from Wako Junyaku Co., Ltd.; boiling point: 146° C.) as a dispersing medium containing no dissociating functional group at a terminal end or a side chain thereof was charged with 2.51 g of yttrium acetate tetrahydrate available from Kanto Kagaku Co., Ltd., 0.025 g of cerium acetate monohydrate available from Kanto Kagaku Co., Ltd., and 2.55 g of AIP available from Kanto Kagaku Co., Ltd.
  • PMEA 1-methoxy-2-acetoxypropane
  • the thus obtained particles were identified by X-ray diffraction using the above method (1).
  • FIG. 10 there are shown the obtained X-ray diffraction pattern as well as JCPDS card corresponding to Y 3 Al 5 O 12 .
  • FIG. 10 it was confirmed that the X-ray diffraction pattern was not consistent at all with that of JCPDS card corresponding to Y 3 Al 5 O 12 . Therefore, it was impossible to identify the reaction product.
  • the wavelengths ⁇ EX and ⁇ EM and the peak intensity I were measured by the above method (4). However, no effective fluorescence was detected.
  • the phosphor obtained from the precipitate was in the form of a yellow transparent paste.
  • the paste was heated to 300° C. in a nitrogen atmosphere to measure a weight reduction thereof. From the measurement, it was confirmed that the amount of the solvent contained in the paste was about 20% by weight, namely the solid content in the paste was 80%. After the heating, the phosphor was formed into a transparent mass.
  • Example 1 The particles obtained in Example 1 and polyethylene glycol (molecular weight: 600) were mixed with each other at a weight ratio of 75:25, thereby producing a yellowish white turbid paste.
  • Two glass substrates were disposed through spacers to form a clearance of 150 ⁇ m therebetween.
  • the above paste was interposed in the clearance between the glass substrates and sealed by a sealing agent,-thereby obtaining a transparent thin film sample.
  • a peak wavelength in the fluorescence spectrum thereof was 525 nm.
  • the absorption spectrum was measured by the method (5), it was confirmed that the transmittance of the thin film sample as measured at a wavelength of 525 nm was 45%.
  • the phosphor obtained from the precipitate was in the form of a yellow transparent paste.
  • the paste was heated to 300° C. in a nitrogen atmosphere to measure a weight reduction thereof. From the measurement, it was confirmed that the amount of the solvent contained in the paste was about 30% by weight, namely the solid content in the paste was 70% by weight. After the heating, the phosphor was reduced in volume and formed into a transparent mass. The solvent was removed from the paste to obtain a transparent solid.
  • the phosphor obtained from the precipitate was in the form of a yellow transparent paste.
  • the paste was heated to 300° C. in a nitrogen atmosphere to measure a weight reduction thereof. From the measurement, it was confirmed that the amount of the solvent contained in the paste was about 25% by weight, namely the solid content in the paste was 75% by weight. After the heating, the phosphor was reduced in volume and formed into a transparent mass. The solvent was removed from the paste to obtain a transparent solid.
  • the phosphor obtained from the precipitate was in the form of a yellow transparent paste.
  • the paste was heated to 300° C. in a nitrogen atmosphere to measure a weight reduction thereof. From the measurement, it was confirmed that the amount of the solvent contained in the paste was about 45% by weight, namely the solid content in the paste was 55% by weight. After the heating, the phosphor was reduced in volume and formed into a transparent mass. The solvent was removed from the paste to obtain a transparent solid.
  • the phosphor obtained from the precipitate was in the form of a yellow transparent paste.
  • the paste was heated to 300° C. in a nitrogen atmosphere to measure a weight reduction thereof. From the measurement, it was confirmed that the amount of the solvent contained in the paste was about 45% by weight, namely the solid content in the paste was 55% by weight. After the heating, the phosphor was reduced in volume and formed into a transparent mass. The solvent was removed from the paste to obtain a transparent solid.
  • Example 12 The yellow transparent paste obtained in Example 12 was heated to 300° C. in an oven purged with nitrogen and held at that temperature for 30 min. The heated product was cooled and then taken out of the oven, thereby obtaining a transparent solid.
  • the thus obtained transparent solid was irradiated with an ultraviolet light having a wavelength of 365 nm, it was confirmed that a green light was emitted therefrom, and the transparent solid was therefore a fluorescent converter.
  • the yellow transparent paste obtained in Example 12 and PEG (average molecular weight: 2000) were weighted and sampled in a beaker at a weight ratio of 1:1, and mixed with each other at about 150° C. on a hot plate.
  • the resultant mixture was applied and spread over a glass substrate to obtain a yellow thin film.
  • the same mixture kept in a heated state was cast into a heat-resistant stainless steel box to obtain a resin substrate having a thickness of 2 mm.
  • the thin film and the resin substrate were irradiated with an ultraviolet light having a wavelength of 365 nm, it was confirmed that a green light was emitted from both thereof, and the thin film and the resin substrate were therefore fluorescent converters.
  • the clearance (film thickness of the paste) formed therebetween was varied as being 100 ⁇ m, 200 ⁇ m and 300 ⁇ m, respectively, to measure a peak intensity-dependency of a fluorescence spectrum obtained therefrom.
  • the film thickness was plotted on an abscissa axis whereas the peak intensity as fluorescent intensity was plotted on an ordinate axis.
  • the result of the plotting is shown in FIG. 15 .
  • the film thickness and the fluorescence intensity exhibited a substantially proportional relation to each other, and it was confirmed that the fluorescence was emitted therefrom at a high efficiency owing to a good transparency of the paste.
  • the film thickness was plotted on an abscissa axis whereas the peak intensity as fluorescent intensity was plotted on an ordinate axis.
  • the result of the plotting is shown in FIG. 15 .
  • the film thickness and the fluorescence intensity exhibited a less dependency relation to each other, and it was confirmed that the fluorescence was emitted therefrom only at a poor efficiency owing to an opaqueness of the paste even when increasing a thickness thereof.
  • Example 9 The yellow transparent paste obtained in Example 9 and polyethylene glycol (molecular weight: 6000) were mixed with each other at a weight ratio of 75:25 while heating to 150° C.
  • the resultant mixture was cast into a stainless steel vat and cooled to room temperature to obtain a substrate having a thickness of 2 mm.
  • the substrate was irradiated with an ultraviolet light having a wavelength of 365 nm, it was confirmed that a green light was emitted therefrom, and the substrate was therefore a fluorescent conversion plate acting as a fluorescent converter.
  • the yellow transparent paste obtained in Example 9 and polyethylene glycol (molecular weight: 6000) were mixed with each other at a weight ratio of 75:25 while heating to 150° C.
  • a resin of a blue light-emitting diode “NSPE520S” available from Nichia Kagaku Co., Ltd. was carefully removed therefrom, and the above mixture was dropped on an exposed light emission portion of the blue light-emitting diode, and then cooled. As a result, it was confirmed that a yellow to greenish white light was emitted from the light-emitting diode when it was turned on.
  • Example 8 The same procedures as in the steps (i) to (iii) of Example 8 were repeated except that the particles used in the step (i) of Example 8 was replaced with the yellow transparent paste obtained in Example 9, to measure an emission spectrum when emitting excited light from the same light source as used in the step (iii). As a result, it was confirmed that the CIE chromaticity coordinates were (0.25, 0.44), and a green light having a brightness of 130 nit was emitted.
  • the metal oxide-based phosphor microfine particles of the present invention have a small particle size as well as a high affinity to and a high dispersibility in light-transmittable resins, and are excellent in water resistance, chemical resistance and heat resistance. Therefore, a fluorescent conversion film, a fluorescent liquid, a fluorescent paste, a phosphor and a fluorescent converter using the metal oxide-based phosphor microfine particles are inhibited from scattering light emitted from a light source, and are extremely practical and useful for converting an excited light emitted from the light source into light having a longer wavelength when disposed on the light source.
  • the light source includes, for example, organic electroluminescent devices, inorganic electroluminescent devices, light-emitting diodes, cold cathode tubes, fluorescent tubes and lasers.

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US10/587,631 2004-01-29 2005-01-26 Metal oxide phosphor microparticle and process for producing the same; utilizing the same, dispersion liquid, fluorescence conversion membrane, method of separating metal oxide phosphor microparticle, fluorescent liquid, fluorescent paste, phosphor and process for producing the same; and fluorescence converter Abandoned US20070166543A1 (en)

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US8152586B2 (en) 2008-08-11 2012-04-10 Shat-R-Shield, Inc. Shatterproof light tube having after-glow

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US8152586B2 (en) 2008-08-11 2012-04-10 Shat-R-Shield, Inc. Shatterproof light tube having after-glow

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US7883641B2 (en) 2011-02-08
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