JPH0324188A - Phosphor composition - Google Patents

Abstract

PURPOSE:To prepare a colored phosphor compsn. with a high luminescence brightness by mixing a phosphor powder with a needlelike conductive powder. CONSTITUTION:100 pts.wt. phosphor powder is mixed with 1-90 pts.wt., pref. 2-60 pts.wt., needlelike conductive powder to give a phosphor compsn. Said conductive powder is one which satisfies the relation of l/m>=2, wherein lis the major axis and m is the minor axis of a particle of the conductive powder. When l/m<2, the properties of the resulting compsn. cannot surpass those of a compsn. produced by conventional technology. Pref., l is 50mum or lower. The word 'needlelike' includes the meaning of 'rodlike', 'pillarlike', 'fibrous', and 'of whisker shape'. Indium oxide, indium oxide contg. tin, tin oxide, and tin oxide contg. antimony are esp. pref. as the conductive powder.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a phosphor composition for low-speed electron beam excitation that emits light at an accelerating voltage of 100 volts or less, that is, for so-called fluorescent display tubes, particularly for color phosphors with high luminance. Concerning fluorescent materials. (Prior Art) It is essential that a phosphor composition for slow electron beam excitation that emits light at an accelerating voltage of several hundred volts or less has appropriate conductivity. Phosphors that emit light in various colors have been known, but with the exception of zinc oxide phosphors that emit blue-green light, most sulfide phosphors and rare earth phosphors exhibit electrical conductivity. First, it is an insulator. Therefore, as a method of making these insulating phosphors conductive, there is a method of mixing an appropriate amount of conductive powder with the phosphor powder, and as a conductive material,
For example, Special Publication No. 52-'23911, No. 52-2391
No. 3, No. 52-23916 contains indium oxide, Japanese Patent Publications No. 59-33153, No. 59-33155, No. 60
In addition to indium oxide, tin oxide and the like are described in No. 8072. However, at present, an economically advantageous and fully satisfactory conductive powder that can be mixed with a phosphor and exhibits high luminance and efficiency has not yet been found.

(Problems to be Solved by the Invention) The conductive powder is required to impart high conductivity to the phosphor without impairing the luminescence properties of the phosphor itself, but there are still none that are satisfactory. ,unknown.
A particular problem is that the conventional method described above requires a relatively large amount of conductive powder, which reduces the phosphor content in the phosphor composition, and eventually the phosphor composition becomes conductive. Even if it is high, the luminescence property is low, so it cannot be a phosphor with high luminance and luminous efficiency. (Means for Solving the Problems) The present inventors have developed color phosphor assemblies for excitation with slow electron beams, and with the expansion of the field of use thereof, the present inventors have endeavored to achieve even higher luminance and higher luminance. In view of the desire for increased efficiency, we conducted intensive research on the shape of conductive materials in order to solve the above problems, and found that by using conductive powder with an acicular shape, the problems of the prior art described above can be solved. We found that this problem could be solved and arrived at the present invention. The reason why the phosphor composition of the present invention has higher luminance than conventional phosphor assemblies, that is, assemblies made of conductive powder and phosphor that do not have a spherical or at least acicular shape according to the present invention, is that Although the details are not clear, 1) it is easier to obtain continuity in the phosphor medium with needle-shaped ones than with spherical ones, and 2)
) Since it is acicular, the conductive powder does not aggregate together.
3) As a result of 1) and 2), it is possible to reduce the content of conductive powder in the composition, so it is possible to use a luminescent phosphor. 4) The acicular conductive powder is particularly compatible with sulfide-based phosphors and rare-earth phosphors;
This is thought to be due to the following reasons. In the present invention, a conductive material having a needle-like shape is one for which It/m≧2, where m is the short axis of the long sleeve of the conductive material. When l/m is less than 2, only a phosphor using a spherical conductive powder manufactured by a conventional method, that is, a phosphor composition comparable to that of a conventional phosphor composition can be obtained. In the present invention, the needle-like shape includes what is called a rod-like shape, a column-like shape, a fiber-like shape, and a whisker-like shape. Although the value of the major axis l is not particularly limited, it is practically preferable that l≦50−. The conductive powder used in the present invention is most preferably made entirely of conductive material having an acicular shape, but it may be a mixture with a conductive material that does not have a acicular shape. However, in order to achieve the object of the present invention, it is necessary that the content of the acicular conductive material in the mixture is 10% by weight or more. If it is less than 10% by weight, the effect of using the needle-shaped conductive material will not be apparent, and the results obtained will be comparable to those of the conventional phosphors. The conductive powder that is a part of the phosphor and materials of the present invention includes, in addition to various metal powders, various metal oxide powders such as titanium oxide, tungsten oxide, niobium oxide, and zinc oxide, and cadmium sulfide and sulfide. Examples include various metal sulfide powders such as copper, but particularly favorable results are obtained when indium oxide, tin-containing indium oxide, tin oxide, and antimony-containing tin oxide are used. In order to produce a conductive material with a needle-like shape, it is necessary to grow the crystal only in the direction, and by using a conductive material with a needle-like shape produced with special attention to this birch. , the present invention can be achieved.

Various methods are known for manufacturing a conductive material having a needle-like shape, and the method is not limited. For example, indium oxide having a needle-like shape or tin-containing indium oxide can be produced by the uniform precipitation method described below. That is, when an excessively water-soluble indium compound and urea are dissolved in water, the temperature is raised, and ammonia is gradually generated by decomposing the urea, a neutralization reaction results in indium hydroxide or indium oxide water having a needle-like shape. You can obtain Japanese products. When this is dried and burned, it becomes indium oxide with a needle-like shape. Furthermore, by adding an appropriate amount of a water-soluble tin compound together with a water-soluble indium compound, tin-containing indium oxide having a needle-like shape can be produced. In addition, special public service No. 62-47811
No. 1, the first chloride solution was prepared in a solution containing a nonionic surfactant.
producing acicular tin oxalate by reacting tin and stannous oxalate;
A method for producing acicular tin oxide by drying and thermally decomposing it is described. Furthermore, when the acicular tin oxalate is reacted with antimony trichloride and thermally decomposed, antimony-containing tin oxide having an acicular shape can be produced. On the other hand, Japanese Patent Publication No. 60-21553 describes a method for producing conductive powder in which a conductive layer made of antimony-containing tin oxide is formed on the surface of titanium oxide powder. In this case, as the titanium oxide powder, for example, JP-A-56-3232
When acicular titanium oxide as described in No. 6 is used, a conductive material having an acicular shape in which titanium oxide is coated with antimony-containing tin oxide can be obtained. When acicular silica, alumina, titanate, etc. are used in place of titanium oxide, conductive materials with corresponding acicular shapes can be obtained.
In this way, a conductive material obtained by coating a needle-shaped body with at least t W compounds selected from the group consisting of indium oxide, tin-containing indium oxide, tin oxide, and antimony-containing tin oxide can also be used. It is included within the scope of the present invention. Above, the needle-shaped conductive material used in the present invention has been described in detail and the manufacturing method has been illustrated and explained, but the manufacturing method is not limited to these, and the needle-shaped conductive material that is already commercially available A conductive material having a shape may be used, and the effect will not change at all.

On the other hand, other phosphor powders of the present invention include sulfide phosphors and rare earth phosphors that emit light of various colors. That is, examples of sulfide-based phosphors include copper-activated zinc sulfide phosphor (ZnS:Cu, green light emitting), copper-activated zinc cadmium sulfide phosphor (Zn+-aCdaS:Cu, provided that Ova≦0.5 green) ~red emission), copper, aluminum activated zinc sulfide phosphor (ZnS:Cu,AI!., green emission), copper, aluminum activated zinc sulfide cadmium phosphor (Zn+-bcdbs 'Cu, A/!, but o <b≦
0.5 green to red luminescence), silver-activated zinc sulfide phosphor (ZnS
:Ag, blue luminescence), root-activated zinc sulfide cadmium phosphor (Zn+-ccdcs:Ag, provided that O<c≦0.9
(blue to red luminescence), silver, aluminum activated zinc sulfide phosphor (ZnS: Ag, Al, blue luminescence), silver, aluminum activated zinc sulfide cadmium phosphor (Zn+-acd4s)
:Ag. Aj2, but 0〈d≦0.9 blue to red light emission)
, gold-activated zinc sulfide phosphor (ZnS:Au, yellow luminescence)
, gold-activated zinc sulfide cadmium phosphor (Zn+-Cd
- S: Au, but O<e≦0.4 (yellow to red luminescence), gold, aluminum activated zinc sulfide phosphor (ZnS
: Au, Al, yellow luminescence), gold, aluminum-activated zinc sulfide cadmium phosphor (Zn+-, Cd, S: Au
, AI, but 0<f≦0.4 (yellow to red light emission), or manganese-activated zinc sulfide phosphor (ZnS:Mn, orange light emission). Examples of rare earth phosphors include phosphors activated with lanthanum, cerium, praseodymium, samarium, europium, terbium, erbium, thulium, etc., and oxysulfides, oxides, and vanadate of yttrium, cadrinium, ruthenium, etc. There are phosphors based on chemical compounds, boric acid compounds, phosphoric acid compounds, etc. Particularly preferred as a structure Tfg of the present invention is a europium-activated yttrium oxysulfide phosphor (Y, O, S
: Eu, red luminescence), europium activated oxide 7}
lium phosphor (Y.03:Eu..red light emitting), europium-activated yttrium vanadate phosphor (YV
Oa: Eu, red light emission), etc. The mixing ratio of the conductive powder is 1 to 90 parts by weight based on 100 parts by weight of at least l types of phosphor powder selected from the above group of phosphor powders.
Parts by weight are appropriate, preferably 2 to 60 parts by weight. If the mixing ratio of the conductive powder is less than 1 part by weight, a phosphor composition with good conductivity cannot be obtained and the luminance will be low. On the other hand, if it exceeds 90 parts by weight, it shows good conductivity, but
&ll As the phosphor content in the precepts decreases, the luminance will eventually decrease. Furthermore, it is desirable that the phosphor powder and conductive powder be mixed as uniformly as possible. The mixing method involves mixing both powders with V
There is a dry method of mixing using a mold mixer, etc., and a wet method of stirring and mixing using a medium such as water or alcohol, both of which can be used. In particular, in the case of a wet method, dispersion using ultrasonic waves is more effective, and after dispersion, the phosphor composition is separated from the medium by filtration or distillation of the medium. The phosphor composition of the present invention thus obtained can be made to emit light using a slow electron beam excitation device. A low-speed electron beam excitation device consists of a filament, which is a cathode set in a vacuum, a grid, and an anode. When the electron beam from the cathode passes through the grid and is irradiated onto a phosphor composition coated on the anode, light is emitted. It will be done. (Example) The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. Production example l (Production of conductive powder) When 100 g of indium nitrate and 230 g of urea are dissolved in 1 liter of water and heated to 90°C or higher, the ammonia released by thermal decomposition of urea reacts with indium nitrate, resulting in a so-called homogeneous solution. Indium hydroxide with a needle-like shape is precipitated by the precipitation method. After filtering, washing and drying, heat at 850°C.
From the MU microscopic photograph of indium oxide having a needle-like shape produced by burning it with m≧2. (See Figure 1) Examples 1 to 4 Copper sulfate and aluminum sulfate were added to high-purity zinc sulfide so that copper and aluminum were both IXI (1'g atom) per 1 mole of zinc sulfide. ZnS was burned at 1000℃ for 2 hours in a reducing atmosphere consisting of hydrogen.
: Cu, Al phosphor was manufactured. The above phosphor 100
Parts by weight and 2, 10, 30, and 60 parts by weight of the needle-shaped indium oxide obtained in Production Example 1 were sufficiently stirred and mixed using ethanol as a medium, and after quickly filtering the solid matter, the mixture was heated under reduced pressure. This was dried to produce a phosphor composition of the present invention. The brightness of the phosphor IJI7ii obtained by the above method was measured using a filament current of 90 mA in a slow electron beam excitation device.
, the relative brightness was determined with the maximum brightness of the phosphor composite sole obtained in Comparative Example 1 described later taken as 100. The result! -1 shows. Table 1 “Phosphor ZnS:Cu,AI! Comparative Example 1 for 100 parts by weight The following method was used as a normal manufacturing method to obtain spherical indium oxide. Namely, 30 parts by weight of indium nitrate
0g to 11 parts water! ．． 5% aqueous ammonia was added dropwise to precipitate spherical indium hydroxide by a heterogeneous precipitation method, and after filtration, washing, and drying, the central MO. Spherical indium oxide with a particle size distribution of 6 m was obtained. (See Figure 2) Next, 100 parts by weight of the ZnS:Cu,Al phosphor used in Example 1 was treated in the same manner as in Example 1, with varying amounts of the spherical indium oxide obtained by the above method. Various phosphors & [
I manufactured some products and compared their maximum brightness. the result,
ZnS: Cu, AI! The highest brightness was obtained when the amount of spherical indium oxide added to the phosphor was 30 parts by weight. This brightness was set as 100, and the brightness obtained in Examples 1 to 7 was compared.

Example 5 The ZnS: Cu, A/! 100 parts by weight of the phosphor and 5 parts of indium oxide having the needle-like shape described in Production Example 1
parts, 15 parts by weight of spherical indium oxide described in Comparative Example 1 (
A total of 20 parts by weight) was added, mixed, filtered and dried in the same manner as in Example 1 to produce a phosphor of the present invention.
The relative brightness of the resulting composition was 120%. Example 6 100 g of indium nitrate, 0.5 g of stannous chloride, and 230 g of urea were dissolved in 1 liter of water, heated in the same manner as in Production Example 1, filtered, washed, dried, and burned to obtain a needle-like shape. A tin-containing indium oxide was produced. The shape is the same as in Production Example 1, Il = 1 to 3μ, m; 0.54 or less, l/m≧
It was 2. Hereinafter, as in Example 1, ZnS:Cu. 10 parts by weight of the tin-containing indium oxide obtained here was mixed with 100 parts by weight of the Al phosphor to produce a phosphor composition. The brightness of the resulting assembly was 140%. Example 7 ZnS: For 100 parts by weight of Cu, Al phosphor, acicular conductive titanium oxide (FT-1) was prepared by coating acicular titanium oxide with a conductive layer made of tin oxide containing antimony.
000: manufactured by Ishihara Sangyo ■) was mixed with 5 parts by weight of phosphor &l.
I produced a precept. Q: 2~5u, m from microscope @ mirror photo
: 0. 0 5 ~ 0. 1 pm, I! / m
It was ≧20. The relative brightness of the resulting composition was 13
It was 0%. Examples 8 to 20 Production Example 1 was applied to various sulfide-based phosphors and rare-earth phosphors.
Various types of phosphors of the present invention were manufactured by mixing indium oxide having a needle-like shape manufactured in . still,
The sulfide phosphor is Z n S : Cu of Example 1.
+ AI! Manufactured in the same manner as the phosphor. For example, when the base material was zinc cadmium sulfide, high-purity zinc sulfide and cadmium sulfide were used, and when the activator was silver, gold, or manganese, silver nitrate, gold chloride, and manganese chloride were used, respectively. or,
The europium-activated yttrium oxide phosphor was produced by dissolving yttrium oxide and an appropriate amount of europium oxide in nitric acid, adding oxalic acid to produce oxalate, and burning the oxalate in air at iooo°C for 2 hours. ．． A europium-activated yttrium vanadate phosphor was also produced in the same manner. Further, the europium-activated yttrium oxysulfide phosphor is prepared by adding an appropriate amount of soda carbonate and sulfur to the europium-activated yttrium oxide phosphor, and then adding an appropriate amount of sodium carbonate and sulfur to the europium-activated yttrium oxide phosphor.
It was produced by reacting at ℃ for 5 hours. On the other hand, various phosphor compositions were produced in the same manner as in Example 1 by adding the spherical indium oxide obtained in Comparative Example 1 to the various phosphors of Examples 8 to 20 and varying the amount. Example 8~ with the brightness when the maximum brightness is obtained as 100
We compared the brightness of each of the 20 images. The results obtained are shown in Table-2.

(Effects of the Invention) This invention provides a novel low-speed electron beam-excited phosphor viewing material, that is, a phosphor composition for a fluorescent display tube.The phosphor composition of the present invention is different from the conventional one. It has higher luminance and efficiency, and is also inexpensive, which will greatly accelerate the colorization of practical fluorescent display tubes and increase its f
It has great commercial value.

[Brief explanation of drawings]

FIG. 1 is a micrograph showing the shape of acicular indium oxide described in Production Example 1, and FIG. 2 is a micrograph showing the shape of spherical indium oxide described in Comparative Example 1, both magnified at 5000 times.

Claims (9)

[Claims] (1) A phosphor composition obtained by mixing a phosphor powder and a conductive powder containing at least 10% by weight of a needle-shaped conductor. (2) The scope of claims (1
) The phosphor composition described. (3) Claims in which the long axis l is 50 μm or less (2
) The phosphor composition described. (4) The phosphor composition according to claim (1), wherein the conductive powder is at least one selected from the group consisting of indium oxide, tin-containing indium oxide, tin oxide, and antimony-containing tin oxide. (5) titanium oxide in which the electrical conductor has a needle-like shape;
Claim (1) wherein the carrier is silica, alumina, or titanate and is coated with at least one member selected from the group consisting of indium oxide, tin-containing indium oxide, tin oxide, and antimony-containing tin oxide. Phosphor composition. (6) Claim (1) in which the mixing ratio of the conductive powder is 1 to 90 parts by weight per 100 parts by weight of the phosphor powder.
The described phosphor composition. (7) The phosphor composition according to claim (1), wherein the phosphor powder is a sulfide phosphor or a rare earth phosphor. (8) The sulfide-based phosphor is a copper-activated zinc sulfide phosphor (Zn
S: Cu), copper-activated zinc sulfide cadmium phosphor (Zn_
1_-_aCd_aS: Cu, however, 0<a≦0.5),
Copper, aluminum activated zinc sulfide phosphor (ZnS:Cu,
Al), copper, aluminum-activated zinc sulfide cadmium phosphor (Zn_1_-_bCd_bS: Cu, Al, but 0
<b≦0.5), silver-activated zinc sulfide phosphor (ZnS:Ag
), silver-activated zinc sulfide cadmium phosphor (Zn_1_-_
cCd_cS: Ag, but 0<c≦0.9), silver, aluminum activated zinc sulfide phosphor (ZnS:Ag, Al),
Silver, aluminum activated zinc cadmium sulfide phosphor (Zn
_1_-_dCd_dS: Ag, Al, however, 0<d≦0
．． 9), gold-activated zinc sulfide phosphor (ZnS:Au), gold-activated zinc sulfide cadmium phosphor (Zn_1_-_eCd_
eS: Au, but 0<e≦0.4), gold, aluminum-activated zinc sulfide phosphor (ZnS: Au, Al), gold, aluminum-activated zinc sulfide cadmium phosphor (Zn_1_-
_fCd_fS: Au, Al, 0<f≦0.4),
or a manganese-activated zinc sulfide phosphor (ZnS:Mn). (9) The rare earth phosphors are europium-activated yttrium oxysulfide phosphor (Y_2O_2S:Eu) and europum-activated yttrium oxide phosphor (Y_2O_3:Eu).
), or a europium-activated yttrium vanadate phosphor (YVO_4:Eu).