JP3783329B2 - Vacuum ultraviolet-excited luminescent phosphor and method for producing the same - Google Patents

Description

【００４１】
【発明の効果】
以上説明したように、蛍光体粒子表面を硼酸系化合物で被覆することによって、蛍光体のベーキング時の酸化による劣化を防止し、放電空間中でのイオン衝撃による劣化も防止することができる。すなわち、本発明の蛍光体を使用することにより、紫外線、特に主としてキセノンの１４７ｎｍ真空紫外線を利用するカラープラズマディスプレイパネルや、キセノン放電型蛍光ランプ等の発光デバイスを高輝度化し、しかも働程特性を改善することが可能となる。
【図面の簡単な説明】
【図１】１４７ｎｍの真空紫外線励起時の相対発光強度と、硼酸系化合物の被覆量の関係を示す特性図（実線はベーク後、破線はベーク前）
【図２】１４７ｎｍの真空紫外線励起時の相対発光強度と、硼酸系化合物の被覆量の関係を示す特性図（実線は放電管の劣化前、破線は劣化後）[0001]
[Industrial application fields]
The present invention relates to a method of manufacturing a phosphor used in a plasma display panel, a high-load fluorescent lamp, a rare gas discharge lamp, or the like, and more particularly, to an improvement in light emission luminance and a working characteristic of a device.
[0002]
[Prior art]
Color plasma display panels or fluorescent lamps basically convert ultraviolet light generated in the discharge space into visible light by a phosphor, and these devices have phosphor particles coated in layers on the inner wall of the discharge space. A phosphor layer.
[0003]
In order to form this phosphor layer, usually, a coating composition in which a phosphor and an organic binder (vehicle) are mixed is applied to a predetermined portion by screen printing or the like, and then 400 to 600 for the purpose of removing the organic binder. Baking at a temperature in the range of ° C. This firing is performed in the air for a sufficient period of time so that undecomposed components do not remain. At this time, the phosphor surface is oxidized at a high temperature because of contact with oxygen in the air, and as a result, light emission occurs. The brightness decreases. Such oxidation is particularly noticeable in phosphors fired in a reducing atmosphere, such as BaMg2Al16O27: Eu phosphors activated with divalent europium.
[0004]
In the plasma display panel (PDP), the excitation source is ultraviolet rays of Xe resonance line 147 nm and molecular beam 172 nm. Since the wavelength is very short, the transmission power is weak and only the phosphor particle surface layer part is excited. Therefore, the light emission characteristics are easily affected by the surface layer portion due to oxidation or the like.
[0005]
Furthermore, in these light emitting devices, the discharge space and the phosphor layer are close to each other, and the phosphor is exposed to ion bombardment and vacuum ultraviolet rays from the discharge space, and these actions increase the emission luminance of the phosphor over time. descend.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances, and an object thereof is to improve the light emission luminance and working characteristics of a phosphor that emits light when excited by vacuum ultraviolet rays.
[0007]
[Means for Solving the Invention]
The inventors of the present invention have considered that the phosphor particles can be prevented from being reduced in luminance by blocking or protecting the phosphor particle surface from the above-described inhibition factors, and as a result of intensive studies, phosphor particles It has been found that by coating the surface with a boric acid compound as a protective substance, the light emission luminance and working characteristics when the phosphor is mounted on a device are remarkably improved, and the present invention has been completed.
[0008]
That is, in the vacuum ultraviolet ray-excited luminescent phosphor of the present invention, the phosphor particle surface is coated with 0.001 to 10 parts by weight of boric acid compound as boron (B) on 100 parts by weight of the phosphor. Features.
[0009]
The phosphor targeted by the present invention is basically a phosphor fired in a reducing atmosphere, but is applied to an aluminate phosphor activated by at least one activator of Eu and Mn. It is effective. In particular, it is effective for a BaMg2Al16O27: Eu phosphor activated with divalent europium.
[0010]
Further, the phosphor of the present invention is prepared by mixing a phosphor and water in which at least one boric acid compound of boric acid, boron oxide, and ammonium borate is dissolved, and drying the slurry. By baking at a temperature of 1000 ° C., the phosphor particles can be obtained by coating the surface of the phosphor particles with a boric acid compound.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
<Boric acid compound coverage>
FIG. 1 is a plot of the relationship between the relative emission intensity of a BaMg2Al16O27: Eu phosphor coated with a boric acid compound and the coating amount of the boric acid compound when excited by vacuum ultraviolet radiation at 147 nm using a vacuum ultraviolet spectrophotometer. Here, the coating amount of the boric acid compound is represented by an analytical value of boron (B). In the figure, the solid line represents the case where the phosphor was baked in air at 450 ° C. for 30 minutes, and the broken line represents the phosphor that was not baked. Although the amount of adhesion of the boric acid compound is slight as shown by the broken line, the relative luminance tends to decrease, and the relative emission intensity is about 95% when the amount is 0.1 parts by weight.
[0012]
As described above, baking is performed for the purpose of removing the binder used when forming the phosphor layer as described above for use in a light emitting device such as a plasma display. Therefore, the relative emission intensity of the phosphor when mounted on an actual light emitting device approximates the case of baking with a solid line.
[0013]
The curve of the baked phosphor shown by a solid line shows a boron analysis value of up to about 0.0001 parts by weight and a relative emission intensity as low as about 60%. However, as the amount of boric acid increases, the emission luminance improves and 0.01 parts by weight. The relative emission intensity of the coated phosphor is over 90%. The coating of 0.01 part by weight or more almost overlaps the solid line that is not baked, and the effect of baking is not observed because the boric acid compound is coated. In other words, it can be said that there is no decrease in luminance due to baking.
[0014]
As shown in FIG. 1, in terms of relative strength, in the present invention, the boric acid compound needs to be coated in the range of 0.001 to 10 parts by weight as boron with respect to 100 parts by weight of the phosphor. It is preferable to coat in the range of 0.01 to 5 parts by weight. If the boron coating amount is less than 0.001, the effect is not recognized, and if it is more than 10 parts by weight, the luminance is greatly lowered and is not suitable for practical use.
[0015]
FIG. 2 is a plot of the relationship between the relative emission intensity at the time of excitation with vacuum ultraviolet rays of 147 nm and the coating amount of the boric acid compound using a vacuum ultraviolet spectrophotometer. In the figure, the solid line shows the BaMg2Al16O27: Eu phosphor baked at 450 ° C. for 30 minutes, and the broken line shows that the phosphor is set in a glass tube sealed with 4 torr of Kr—Xe—He mixed gas with a current of 1.2 A. , Phosphors having a surface deteriorated by arc discharge at a voltage of 130 V for 1 hour, respectively.
[0016]
As shown in FIG. 2, the phosphor with the boric acid compound attached to the particle surface has a smaller deterioration rate due to the discharge tube of the mixed gas of Kr—Xe—He as the amount of B attached increases. However, since the relative emission intensity decreases as the adhesion amount of the boric acid compound increases, it is practically necessary that the coating amount is less than 10 parts by weight as B with respect to 100 parts by weight of the phosphor.
[0017]
As boric acid compounds, metal borates such as Ba, Ca, Sr, Mg, Zn, Y, Gd, Lu, Sc, and La can be used, but these absorb vacuum ultraviolet rays that are excitation sources. It is preferable to use nonmetallic salts such as oxides such as B2O3 and B4O5, boric acids such as H3BO3, H3B4O7, and HBO2, or ammonium salts of boric acids.
[0018]
<Boric acid compound coating method>
In order to coat the phosphor particles with the boric acid compound, first, a predetermined amount of boric acid compound is mixed with the phosphor. This mixing is preferably performed as homogeneously as possible. This is because the boric acid compound film formed on the surface of the phosphor particles is preferably as homogeneous as possible. The actual coating is performed by firing in the next step, but it is preferable to perform the coating more uniformly in this step because the firing temperature can be set lower.
[0019]
For homogeneous mixing, a water-soluble boric acid compound is selected, added to the phosphor suspension, and dried (evaporated to dryness) to uniformly coat the phosphor particle surface. it can. Such water-soluble boric acid compounds include oxides such as B2O3 and B4O5, boric acids such as H3BO3, H3B4O7, and HBO2, or ammonium salts of boric acids.
[0020]
Among these boric acid compounds, those with low solubility do not dissolve in the required amount of water, and some or most of them adhere to the surface of the phosphor particles, but among these, the melting point is high Since the smaller the particle diameter, the smaller the particle size, the surface of the phosphor particles can be coated. Accordingly, the particle size of the boric acid compound adhering to the phosphor particle surface is preferably about 0.1 μm or less.
[0021]
<Baking temperature>
The boric acid compound uniformly coated on the phosphor surface is calcined at a temperature of 300 to 1000 ° C. The boric acid compound is calcined at a high temperature to produce a strong glassy coating on the phosphor particle surface. In addition, the optical transparency of the coating is improved, and at the same time, the coating is chemically and physically stabilized. When the firing temperature is lower than 300 ° C., the boric acid compound coating agent does not sufficiently diffuse on the surface of the phosphor particles, and the effect of the present invention cannot be expected. Conversely, if the firing temperature is higher than 1000 ° C., the coating agent diffuses into the phosphor particles, and the phosphor deteriorates and loses the effect of vitrification of the surface with boric acid. To do. Therefore, the firing temperature is more preferably in the range of 600 to 900 ° C. Most preferred is around 800 ° C. As described above, the firing temperature is preferably as low as possible for the phosphor matrix, but the effect of the glass is reduced as the temperature is lowered. Therefore, it is effective at low temperatures to deposit the boric acid compound as uniformly as possible on the surface of the phosphor particles in the previous step.
[0022]
<Baking atmosphere>
When firing at a relatively low temperature in the range of 300 to 500 ° C., the firing atmosphere may be in air, but when firing at a relatively high temperature in the range of 500 to 1000 ° C., is it a neutral atmosphere such as N 2 or Ar? Alternatively, a weak reducing atmosphere such as an N2-H2 mixed gas atmosphere or a CO2-CO mixed gas atmosphere is desirable.
[0023]
[Action]
Ultraviolet rays used for phosphor-excited light emission are mainly emitted from 365 nm from a high-pressure mercury lamp, 253.7 nm obtained with high efficiency from low-pressure mercury vapor discharge, 184.9 nm partially emitted from the discharge, and xenon discharge. However, the shorter the ultraviolet wavelength, the smaller the transmission power. Conversely, the longer the ultraviolet wavelength, the higher the transmission power. That is, it is relatively near the surface of the phosphor that is excited by vacuum ultraviolet rays such as 184.9 nm or 147 nm. On the other hand, the portion oxidized by baking is near the surface of the phosphor, and is not necessarily oxidized to the inside of the phosphor. Therefore, those that emit light with vacuum ultraviolet light are more susceptible to oxidation due to baking. In other words, the vacuum ultraviolet-excited phosphor can greatly improve the phosphor performance by improving the baking.
[0024]
Therefore, the present invention works effectively with a phosphor whose activator is Eu ²⁺ , Mn ²⁺ , Ce ³⁺ , Tb ³⁺ , Sb ³⁺ , or Sn ²⁺ . It is a phosphor that is easily oxidized and efficiently excited and emitted by vacuum ultraviolet rays. Such phosphors include BaMg2Al16O27: Eu, BaMg2Al16O27: Eu, Mn, Sr4Al14O25: Eu, Zn2SiO4: Mn, LaPO4: Ce, Tb, MgAl11O19: Ce, Tb, Y2SiO5: Tb, and the like. Among these, it is particularly effective for an alumina hydrochloride phosphor using Eu ²⁺ or Mn ²⁺ as an activator.
[0025]
【Example】
Examples of the present invention will be described by taking BaMg2Al16O27: Eu, which is one of aluminate phosphors activated by divalent europium, as an example.
[0026]
First, this phosphor can be manufactured as follows by a conventional method. Weigh the following as raw materials,
BaCO3 ··········· 0.90 mol 3MgCO 3 · Mg (OH) 2 · 3H 2 O ··· 0.50 mol γ-Al 2 O 3 ········・ ・ ・ ・ 8.00 mol Eu2O3 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.05 mol Add 100 parts by weight of AlF3 to 100 parts by weight of the total amount. And ball mill mix in a magnetic pot.
[0027]
The obtained mixed raw material is filled in an alumina crucible with a lid and fired in air at 1500 ° C. for 8 hours. After cooling, it is further calcined at 1500 ° C. for 8 hours in a reducing atmosphere of N 2 —H 2. After cooling, dispersion treatment was carried out, passed through a 300 mesh sieve, and then dehydrated and dried.
[0028]
The obtained phosphor has a composition of BaMg2Al16O27: Eu0.1 and emits blue light when excited with 147 nm ultraviolet rays. (Hereinafter referred to as BAM phosphor)
[0029]
[Example 1]
To 100 g of the obtained BAM phosphor, 0.1 g of H3BO3 and 100 g of water are added and mixed to form a slurry, and then dried at 100 ° C. After drying, it was filled in an alumina crucible and fired at 400 ° C. for 1 hour in the air using an electric furnace to obtain the phosphor of the present invention. According to the result of chemical analysis of the phosphor, boron was 0.017 part by weight with respect to 100 parts by weight of the phosphor.
[0030]
[Example 2]
The phosphor of the present invention was obtained by adding 0.5 g of H3BO3 and 100 g of water to 100 g of the BAM phosphor and performing the same operation as in Example 1. According to the result of chemical analysis of the phosphor, boron was 0.085 parts by weight with respect to 100 parts by weight of the phosphor.
[0031]
[Example 3]
2.5 g of H3BO3 and 100 g of water were added to 100 g of the BAM phosphor, and the same operation as in Example 1 was performed to obtain the phosphor of the present invention. According to the result of chemical analysis of the phosphor, boron was 0.43 parts by weight with respect to 100 parts by weight of the phosphor.
[0032]
[Example 4]
12.5 g of H3BO3 and 100 g of water were added to 100 g of the BAM phosphor, and the same operation as in Example 1 was performed to obtain the phosphor of the present invention. According to the result of the chemical analysis of the phosphor, boron was 2.1 parts by weight with respect to 100 parts by weight of the phosphor.
[0033]
[Example 5]
25.0 g of H3BO3 and 100 g of water were added to 100 g of the BAM phosphor, and the same operation as in Example 1 was performed to obtain the phosphor of the present invention. According to the result of the chemical analysis of the phosphor, boron was 4.3 parts by weight with respect to 100 parts by weight of the phosphor.
[0034]
[Example 6]
To 100 g of BAM phosphor, 1 g of ammonium borate and 100 g of water are added and mixed to form a slurry and then dried. After drying, it was filled in an alumina crucible and fired at 800 ° C. for 1 hour in an H 2 —N 2 atmosphere to obtain the phosphor of the present invention. According to the result of the chemical analysis of the phosphor, boron was 0.14 parts by weight with respect to 100 parts by weight of the phosphor.
[0035]
[Example 7]
100 g of BAM phosphor was added to 500 g of water while stirring to completely suspend the phosphor, 30.93 g of Y (NO3) dissolved in 50 g of water was added dropwise, and then H3BO3 dissolved in 50 g of water was added. . After dropwise addition of 34 g, aqueous ammonia is added to adjust the pH to 8. After leaving it for 1 hour, it was sufficiently washed with water and dried while dehydrating to obtain the phosphor of the present invention. According to the result of chemical analysis of the phosphor, boron was 0.022 parts by weight with respect to 100 parts by weight of the phosphor.
[0036]
[Comparative Example 1]
A phosphor that does not cover the phosphor particle surface with a boric acid compound such as H3BO3 as in the present embodiment is selected. That is, it is a phosphor before the phosphors of Examples 1 to 7 are coated.
[0037]
[Comparative Example 2]
Instead of coating the phosphor particle surface, a phosphor obtained by charging a phosphoric acid compound into a phosphor material and firing it was prepared as follows.
[0038]
Weigh the following as raw materials,
BaCO3 ··········· 0.90 mol 3MgCO 3 · Mg (OH) 2 · 3H 2 O ··· 0.50 mol γ-Al 2 O 3 ········ ········ 8.00 mol Eu 2 O 3 ·············································· In addition to 1.0 part by weight of AlF. Add 0.1 part by weight of H3BO3 and ball mill mix in a magnetic pot. The obtained mixed raw material was manufactured by the same method as the BAM phosphor before coating with the boric acid compound used in Examples 1 to 7 described above.
[0039]
BAM phosphors 5g obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were packed in a magnetic crucible and baked at 450 ° C. for 30 minutes using an electric furnace, and luminance comparison tests before and after baking, and a rare gas discharge tube The test was conducted. The results are shown in Table 1. Further, the emission intensity maintenance ratio was calculated as emission intensity after baking / emission intensity before baking × 100%.
[0040]
[Table 1]

[0041]
【The invention's effect】
As described above, by coating the phosphor particle surface with a boric acid compound, deterioration due to oxidation during baking of the phosphor can be prevented, and deterioration due to ion bombardment in the discharge space can also be prevented. That is, by using the phosphor of the present invention, a light emitting device such as a color plasma display panel or a xenon discharge fluorescent lamp using ultraviolet rays, particularly xenon's 147 nm vacuum ultraviolet rays, has high brightness and has a working characteristic. It becomes possible to improve.
[Brief description of the drawings]
FIG. 1 is a characteristic diagram showing the relationship between the relative emission intensity when excited by vacuum ultraviolet radiation at 147 nm and the coating amount of a boric acid compound (the solid line is after baking, and the broken line is before baking)
FIG. 2 is a characteristic diagram showing the relationship between the relative emission intensity when excited by vacuum ultraviolet rays at 147 nm and the coating amount of a boric acid compound (the solid line is before deterioration of the discharge tube, and the broken line is after deterioration).

Claims (2)

On the particle surface of the aluminate phosphor activated by at least one activator of Eu and Mn, a glassy boric acid compound as boron (B) is 0.001 to 100 parts by weight of the phosphor. A vacuum ultraviolet-excited luminescent phosphor characterized by being coated with 10 parts by weight. The phosphor is mixed with water in which at least one boric acid compound of boric acid, boron oxide and ammonium borate is dissolved and the phosphor is mixed to prepare a slurry, and the slurry is dried, and then at a temperature of 600 to 900 ° C. A method for producing a vacuum ultraviolet-excited luminescent phosphor, characterized in that the surface of the phosphor particles is coated with a boric acid-based compound by firing with a vacuum.

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