JP2799751B2 - Yellow zinc sulfide phosphor for improved electroluminescence - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a zinc sulfide phosphor for voltage emission. More particularly, the present invention relates to zinc sulfide phosphors having improved brightness, which are synergistically activated by manganese, copper and chloride ions.

[Problems to be Solved by the Prior Art and the Invention] The composition of the phosphor for electroluminescence of zinc sulfide which emits yellow light is disclosed in US Pat. Nos. 2,743,238, 2,772,242, 3.076,767.
And 3,775,173.

U.S. Pat. No. 2,743,238 discloses that zinc sulfide electroluminescent phosphors can be activated with copper in the range of 0.05-1% by weight and manganese in the range of 0.1-10% by weight. Also, the patent teaches that the brightness of the phosphor can be improved by mixing zinc sulfide with about one-third its weight of zinc oxide, and zinc oxide is a material of the above-mentioned material. The phosphor is washed away from the phosphor by washing with acetic acid after firing. In another method, some of the zinc sulfide is converted to zinc oxide by controlled oxidation during the firing step.

U.S. Pat. No. 2,772,242 teaches that the addition of small amounts of lead further improves the phosphor, and washing after calcining to dissolve free zinc oxide also increases emission. This patent teaches the use of zinc oxide for reasons of excessive conductivity. Manganese levels of about 0.0001 to about 0.03 gram atoms per mole of ZnS are disclosed.

U.S. Pat.No. 3,076,767 discloses that a phosphor is formed by first forming a zinc sulfide material containing copper, chloride, then etching the material with hydrogen peroxide, and adding manganese carbonate and copper sulfate. Teaches that when produced by firing again, the resulting phosphor has a better brightness than the unetched phosphor. The level of manganese retained is not disclosed, but it is stated that after drying, 4% manganese (as manganese carbonate) is added and calcined at 800 ° C. The phosphor has an efficiency of 4.4 lumens / watt.

U.S. Pat. No. 3,775,173 teaches that zinc sulfide phosphors for manganese-activated electroluminescence can be improved by immersion in an aqueous solution of a copper salt. The level of manganese retained is disclosed to be 0.1-0.5% by weight.
Manganese chloride is used as a manganese source.

Commercially available zinc sulfide phosphors for electroluminescence are activated by about 1.3% by weight of manganese, about 0.03% by weight of chloride and about 0.05% by weight of copper and are produced using conventional electroluminescent lamps.
It has a lumen efficiency of about 5.2 lumens / watt when measured at 5/400 Hz.

SUMMARY OF THE INVENTION According to one aspect of the present invention, the voltage of zinc sulfide activated by about 0.7 to about 1.3% by weight of manganese, based on the total weight of the phosphor composition. An improved phosphor comprising a light emitting phosphor, wherein the phosphor emits a voltage emission of about 0.522 to about 0.522.
The phosphor is provided having an X color coordinate value of about .532 and a Y color coordinate value of about .460-.470 and having an efficiency of greater than about 5.6 lumens at 115 V / 400 Hz.

According to another aspect of the invention, a) blending a chloride source, a copper source, and zinc sulfide to form a relatively uniform mixture; b) subjecting the resulting mixture to about 1000 ° C to about 1300 ° C. Heating at a temperature of about 2 to about 8 hours to convert at least a portion of the mixture to a crystalline material containing zinc sulfide, at least some chloride and copper ions, c) transforming the resulting material Washing with sufficient water to remove at least a major portion of the water-soluble substances from the crystalline material; d) drying the crystalline material to produce a relatively moisture-free material; Subjecting the dry material to low intensity milling for a sufficient time to change the crystal structure of at least a portion of the wet material; f) cooling the cooled material to about 2.0
Blending with a sufficient amount of manganese carbonate to achieve a concentration of manganese of about 3.6% by weight to form a second mixture; g) mixing the second mixture at a temperature of about 750 ° C. to about 850 ° C. for about 1.5 to about 850 ° C. Heating for 3 hours to form an activated material by incorporating from about 0.7% to about 1.3% by weight of manganese into the zinc sulfide crystal lattice; h) combining the activated material with a reactive aqueous solution Washing the material to remove residual flux and excess activator material; and i) drying the washed material to form a voltage-emitting phosphor having increased brightness. The method of manufacturing, wherein the emission of the voltage emission of the phosphor is approximately 0.522 to the X color coordinate value.
Provided above is a method having about .532 and a Y color coordinate value of about .460 to .470, wherein the phosphor has an efficiency at 115 V / 400 Hz of greater than about 5.6 lumens.

DETAILED DESCRIPTION For a better understanding of the present invention, together with other objects, advantages and possibilities of the invention, reference is made to the following disclosure and claims in connection with the above several aspects of the invention. You.

The manufacturing technology for manufacturing the zinc sulfide electroluminescent phosphor generally includes the following continuous steps. A first mixture is formed and heated to form a crystalline form of zinc sulfide that incorporates at least some chloride and copper ions. The resulting heated mixture is washed with water to remove substantially all water-soluble material from the crystalline material, and then dried. Thereafter, the dried material is subjected to low-strength milling for a sufficient time to change the crystal structure of at least a portion of the dried material. The material is then blended with a specific amount of manganese source to produce a specific lower manganese concentration and heated to form an activated material that incorporates a specific level of manganese as retained manganese. The resulting EL phosphor has a fluorescence efficiency of greater than about 5.6 lumens / watt at 115V / 400Hz with specific color coordinates, compared to a normal commercial material having a radiation efficiency of about 5.2 lumens / watt. Thus, a substantial increase in efficiency has been achieved. Generally, zinc sulfide is first added to a copper source, such as copper sulfate, and a flux, such as an alkali metal chloride, alkaline earth chloride, or mixtures thereof, at about 1000 ° C. Firing at a temperature of about 1300C for about 2 hours to about 8 hours. Calcination converts the bulk of the mixture to a crystalline material containing zinc sulfide and copper and chloride ions. The resulting material is washed with sufficient water to remove water-soluble substances. Generally, when the wash water has a conductivity of less than about 30 micromhos, it indicates that substantially all of the water-soluble material has been removed. It is preferable to use deionized water as the washing water. After washing, the material is dried and subjected to a low strength milling process. Milling is performed for a sufficient time to change at least a part of the material from a hexagonal structure (crystal system) to a cubic structure (crystal system). Thereafter, the milled material is reduced to about 2.0 to
Firing at a lower temperature, i.e., a temperature of about 750 <0> C to about 850 <0> C, for about 1.5 to about 3 hours, with a sufficient amount of manganese ion source to produce a manganese concentration of about 3.6% by weight. Manganese salts of mineral acids are preferred, and manganese carbonate is more preferred. A material incorporating about 0.7 to about 1.3% by weight manganese is formed. Thereafter, the manganese-containing material is washed with a reactive aqueous solution to remove residual substances. Preferred aqueous solutions include acetic acid, and hydrochloric acid and aqueous potassium cyanide solution. The unreacted zinc material is removed from the activated material using acetic acid. The unreacted manganese material is removed from the activated material using hydrochloric acid. Similarly, the activated material is washed with an aqueous solution of potassium cyanide to remove excess copper material.

The washed material is dried to form a phosphor for voltage emission having increased brightness. The phosphor's electroluminescent radiation has an X color coordinate value of about .522 to about .532 and about .460 to about .470.
And the phosphor has an efficiency of greater than about 5.6 lumens / watt at 115V / 400Hz. If particles of an undesirable size are formed, the material is subjected to a particle size removal step by removing small and large particles to yield a material having particles in the range of about 15 to about 16 μm. Average particle sizes in the range of about 25 to about 30 μm are preferred.

In order to more fully illustrate the present invention, the following detailed examples are set forth. All parts, ratios, and percentages are by weight unless otherwise indicated.

EXAMPLES Example 1 Copper sulfate was mixed with zinc sulfide powder in an amount sufficient to achieve a copper concentration of about 0.05% by weight of zinc sulfide. A chloride flux is blended with the above mixture in an amount equivalent to about 8% by weight of zinc sulfide. The flux consists of 3% barium chloride, 3% magnesium chloride and 2% sodium chloride, each percentage being the weight percentage of zinc sulfide. The mixture is then placed in air, in a covered crucible for about 1200
Calcination at a temperature of 5 ° C. for 5 hours 15 minutes gives a well crystallized starting material. The resulting crystalline material is then washed in water until the excess halide is removed as determined by measuring the conductivity of the used wash water. A conductivity of less than 30 micromoh indicates that excess material has been removed. Thereafter, the phosphor is dried at a temperature of about 110 ° C. The dried material is milled using a low strength milling process in about 1.5 hours. The time is sufficient to change the crystal structure of at least a portion of the dried material.

Then, the starting material of the phosphor which does not emit light by voltage essentially is manganese as manganese carbonate and 1 as copper sulfate.
Activated with 5% copper and 5.8% zinc as zinc sulfate and calcined in air, in a covered crucible, at a temperature of 800 ° C. for 2 hours. Each percentage is the weight percentage of the phosphor starting material.

After activation, the phosphor is washed with acetic acid / water (volume ratio 0.2 / 1), hydrochloric acid / water (volume ratio 0.3 / 1), and potassium cyanide / water (0.048 kg / l). After that, add about 110
Dry at a temperature of ° C.

Example 2 Nine samples of voltage-emitting phosphors were produced by the method of Example 1 with varying levels of manganese carbonate. All other variables remain constant. Table 1 and Table 2
By reducing manganese carbonate to about 50 to about 90 weight of the amount described in U.S. Pat. No. 3,076,767, from about 107.7% to about 113.4% of phosphors using manganese described in Example III of that patent. % Of the phosphor. The measurement was performed at 115 V / 400 Hz using a conventional voltage emission lamp.

As can be seen from the two tables, for materials with an acceptable emission color, the retained manganese is reduced to about 0.7
Should be greater than%. The content of retained manganese is essentially the same in tests 1, 2 and 3, but the data indicate that if the level of manganese carbonate used is greater than about 0.08 parts per zinc sulfide, the brightness or This shows that the efficiency decreases.

While what has been shown and described what is considered to be preferred embodiments of the invention, those skilled in the art can make various changes and modifications without departing from the scope of the invention as defined by the appended claims. It is self-evident.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Christopher S. Poss Willowdon Drive, Towanda, Pennsylvania, USA 302 (58) Field surveyed (Int. Cl. ⁶ , DB name) C09K 11/00-11 / 89 H01J 61/44

Claims (9)

(57) [Claims] 1. A phosphor composition comprising electroluminescent phosphor particles of zinc sulfide activated by manganese at 0.7% to 1.3% by weight based on the total weight of the phosphor composition, The emission of the voltage emission of the phosphor has an X color coordinate value of .522.
~ .532 and Y color coordinate values from .460 to .470, 115V / 400Hz
The phosphor composition having an efficiency greater than 5.6 lumens. 2. The phosphor composition of claim 1 wherein the retained manganese is 1.0-1.3% by weight of the composition and has an efficiency at 115/400 Hz of greater than 5.6 lumens / watt. 3. The phosphor composition according to claim 1, which has a particle size of 15 to 60 μm. 4. The phosphor composition according to claim 1, having an average particle size of 25 to 30 μm. 5. A mixture of a chloride flux, a copper source, and zinc sulfide to form a relatively uniform mixture. B) The resulting mixture is treated at a temperature of 1000 ° C to 1300 ° C at a temperature of 2-8 ° C.
Heating for a time to convert at least a portion of the mixture to a crystalline material containing zinc sulfide, at least some chloride and copper ions, c) washing the resulting material with sufficient water Removing at least a majority of the water-soluble material from the crystalline material; d) drying the crystalline material to produce a relatively moisture-free material; e) replacing said moisture-free material with said moisture-free material. Subjecting the material to low strength milling for a time sufficient to alter the crystal structure of at least a portion of the material; and f) cooling the cooled material to achieve a manganese concentration of 2.0% to 3.6% by weight, based on the amount of zinc sulfide. B) heating the second mixture at a temperature of 750 ° C. to 850 ° C. for 1.5 to 3 hours to form 0.7% to 1.3% by weight of manganese; Containing activated material containing H) washing the activated material with a reactive aqueous solution to remove residual flux and excess activator material, and i) drying the washed material to provide electroluminescence with increased brightness A method for producing a voltage-emitting phosphor, comprising forming a phosphor for voltage emission, wherein the emission of the voltage emission of the phosphor is an X-color coordinate value of .522 to .532.
And the Y color coordinate value is .460 to .470, and the phosphor is 115 V / 4.
A method for producing the phosphor for voltage emission having an efficiency of greater than 5.6 lumens at 00 Hz. 6. The method of claim 5, wherein said activated material is washed with acetic acid to remove unreacted zinc material. 7. The method of claim 5, wherein said activated material is washed with hydrochloric acid to remove unreacted manganese material. 8. The method of claim 5 wherein said activated material is washed with an aqueous solution of potassium cyanide to remove excess copper material. 9. The method according to claim 5, wherein the electroluminescent phosphor is subjected to a particle size separation operation to produce a material having a particle size of 15 to 60 μm.