Classifications

• • 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 materials, e.g. electroluminescent or chemiluminescent
  • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
  • C09K11/025—Use of particular materials as binders, particle coatings or suspension media therefor non-luminescent particle coatings or suspension media
• • 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 materials, e.g. electroluminescent or chemiluminescent
  • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
  • C09K11/58—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing copper, silver or gold
  • C09K11/582—Chalcogenides
  • C09K11/584—Chalcogenides with zinc or cadmium
• • 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 [2D] radiating surfaces
  • H05B33/14—Light sources with substantially two-dimensional [2D] 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

Definitions

• TECHNICAL FIELD This application relates to a process for producing an electroluminescent phosphor, and more particularly, to a process that produces an electroluminescent phosphor with a desired emission spectra.
• Electroluminescent (hereinafter EL) phosphors are used for backlighting in LCD's, in copying machines, for backlighting membrane switches, for automotive dashboard and control switch illumination, for automotive exterior body lighting, for aircraft style information panels, for aircraft information lighting, and for emergency egress lighting.
• EL Electroluminescent
• U.S. Pat. Nos. 3,014,873; 3,076,767; 4,859,361; 5,009,808 and 5,1 10,499 relate to methods for producing EL phosphors. Since EL phosphors are sensitive to moisture it is not uncommon for the phosphors to be coated with a moisture-resistant coating of a metal oxide such as alumina.
• Such coating processes have involved reacting the phosphor, via a chemical vapor deposition process, with a coating agent such as, for example, trimethylaluminum and water vapor.
• a coating agent such as, for example, trimethylaluminum and water vapor.
• An example of such a coated phosphor is shown as Sample Number CJ564 in TABLE I and as CJ30 in TABLE II.
• the phosphor coating in the first instance, contains 4.4 weight percent (hereinafter wgt. %) aluminum, has a Y color coordinate of 0.199 on the C.I.E. Chomaticity Diagram (X value, 0.158) and a half-life of 195 hours and, in the second instance, 4.0 wgt.% aluminum, a Y value of 0.203 and a half-life of 256 hours.
• the half-life refers to that period of time when the brightness of the phosphor decreases to V of its brightness at 24 hours.
• a different coating process having many advantages over the TMA/water process comprises reacting a coating agent such as TMA with an oxygen-ozone mixture.
• This latter process is water-free; however, in some instances this process produces undesired emission changes in the phosphor.
• Even though such phosphors have achieved some commercial success in areas where, for example, brightness might be more desirable than a particular emission spectra, it would be an advance in the art to provide a process for achieving a desired emission spectra in a phosphor having a moisture-sensitizing coating applied by an oxygen-ozone process.
• This invention achieves these and other objectives, in one aspect of the invention, by providing a process for making an electroluminescent phosphor having a given emission spectra A, which comprises the steps of manufacturing a beginning electroluminescent phosphor having an emission spectra B, different than A.
• This beginning phosphor has applied thereto a coating to increase the resistance of the beginning phosphor to the deleterious effects of moisture while simultaneously changing the emission spectra of the beginning phosphor from B to emission spectra A.
• the process is water-free and comprises reacting a coating agent with a coating precursor and a mixture of oxygen and ozone.
• Utilization of this method not only provides a phosphor with a desired emission and moisture protection, but, surprisingly, greatly increases the life.
• This invention provides a process for producing an electroluminescent phosphor that has a commercially desirable emission spectra, moisture protection, long life and high brightness.
• the invention is especially suited for zinc sulfide, copper activated phosphors or other zinc sulfide phosphors where copper is a co-activator, for example, with chlorine.
• control phosphors having Sample Numbers of ELB849, ELB875, and ELB826.
• a process for making an electroluminescent phosphor having a given emission spectra A which comprises first, manufacturing a beginning electroluminescent phosphor having an emission spectra B, different than A.
• This beginning phosphor has applied thereto a coating to increase the resistance of the beginning phosphor to the deleterious effects of moisture while simultaneously changing the emission spectra of the beginning phosphor from B to emission spectra A.
• the process is water-free and comprises reacting a coating agent with a coating precursor and a mixture of oxygen and ozone.
• a beginning ZnS.Cu phosphor was prepared by increasing the normal amount of copper contained therein, from 0.032 wgt.% to 0.039 wgt.% (as determined by atomic absorption analysis). This is a significant increase and raised the Y coordinate to about 0.250 while leaving the X coordinate substantially unaffected.
• the phosphor composition of this invention was prepared from materials as follows:
• the beginning phosphor was produced from the above-cited materials by the standard method of heating the zinc sulfide in a furnace to an elevated temperature in the presence of the copper activator and halide fluxes to achieve an electroluminescent phosphor, cooling the phosphor to ambient temperature and washing the phosphor to remove the flux. The resulting ZnS.Cu phosphor was then dried. Phosphors created by this method are generally known.
• modified Type 813 i.e., a phosphor having an increased amount of
• TABLE II a standard Type 60 0 production lot (CJ30) which is a Type 813 phosphor treated with TMA/H 2 O coating process 1 is included in TABLE II for comparison. While the flow rates of nitrogen through the TMA 2 container were maintained at 0.75 1/minute, rates of nitrogen flow at the bottom of the reactor 3 were kept at a total of 3.75 1/minute. Also, the oxygen/ozone gas mixture was transported 4 into the reaction vessel at a flow rate of 4.6 1/minute. The resulting data on the coated 5 phosphors are shown in TABLE II. 6 TABLE II
• the initial brightness 1 at 24 hours of TH92A (WNE600) lamp was measured at 15 foot lamberts, which is 40% greater than that obtained with the standard CJ30 lot that was prepared by the TMA/H 2 0 process.
• the half-lives of the lamps were enhanced more than 150%, for example, 256 hours with the standard lot CJ30 versus 663 hours with Lot TH92A.
• the greater the amount of aluminum deposit i.e. the greater the coating thickness, the longer the half-life.
• the half-life of TH93 (NE600) with a coating weight of 4.1 % aluminum was estimated at 1295 hours which is about five times the 256 hours of the standard DJ30 lot.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Luminescent Compositions (AREA)
• Electroluminescent Light Sources (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

Country Status (8)

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• 2000
  • 2000-11-15 EP EP00978609A patent/EP1412098A4/de not_active Withdrawn
  • 2000-11-15 CA CA002381534A patent/CA2381534A1/en not_active Abandoned
  • 2000-11-15 AU AU16059/01A patent/AU1605901A/en not_active Abandoned
  • 2000-11-15 KR KR10-2002-7000918A patent/KR100498686B1/ko not_active Expired - Fee Related
  • 2000-11-15 WO PCT/US2000/031216 patent/WO2001036559A2/en not_active Ceased
  • 2000-11-15 JP JP2001539040A patent/JP2003535153A/ja active Pending
  • 2000-11-15 CN CN00815675.1A patent/CN1256185C/zh not_active Expired - Fee Related
  • 2000-11-15 HU HU0500636A patent/HUP0500636A3/hu unknown

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