JPH10298548A - Light-emitting fluorescent material when subjected to vacuum ultraviolet excitation and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject fluorescent material remarkably improved in luminance and life performance by coating the particle surfaces of a fluorescent material with a boric acid-based compound. SOLUTION: This fluorescent material is obtained by coating the particle surfaces of a fluorescent material with 0.001 to 10 pts.wt. of a boron compound based on 100 pts.wt of the fluorescent material. This boron compound is preferably and effectively applied to esp. BaMg2 Al16 O27 :Eu fluorescent material activated by bivalent europium. As the boron compound, an oxide such as B2 O3 , a boric acid compound such as H3 BO3 or ammonium salt of boric acid compound is preferably used. The objective fluorescent material is obtained by preparing a slurry as a mixture of a fluorescent material and an aqueous solution of a boric acid-based compound such as boric acid and dehydrating the slurry, followed by baking it at 300 to 1,000 deg.C, pref. 800 deg.C. Preferably, the particle diameter of the boric acid-based compound deposited onto the surface of the fluorescent material is <=0.1 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a phosphor used for a plasma display panel, a high-load fluorescent lamp, a rare gas discharge lamp, and the like. Regarding improvement.

[0002]

2. Description of the Related Art A color plasma display panel or a fluorescent lamp basically converts ultraviolet light generated in a discharge space into visible light by a fluorescent material. Has a phosphor layer applied in layers.

In order to form the phosphor layer, usually, a coating composition obtained by mixing a phosphor and an organic binder (vehicle) is applied to a predetermined portion by screen printing or the like, and then the organic binder is removed for the purpose of removing the organic binder. 400-600
Firing at a temperature in the range of ° C. This firing is performed in air for a sufficient time so that undecomposed components do not remain,
At this time, since the phosphor comes into contact with oxygen in the air at a high temperature, the phosphor surface is oxidized, and as a result, the emission luminance decreases. Such oxidation is particularly remarkable in a phosphor fired in a reducing atmosphere, such as a BaMg2Al16O27: Eu phosphor activated with divalent europium.

A plasma display panel (PD)
In P), the excitation source is Xe resonance line 147 nm.
And ultraviolet rays having a molecular beam of 172 nm. Since the wavelength is very short, the transmittance is weak, and only the surface layer of the phosphor particles is excited. Therefore, its light emission characteristics are easily affected by the surface layer due to oxidation or the like.

Further, 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 or vacuum ultraviolet rays from the discharge space, and the light emission luminance of the phosphor is greatly reduced with time due to these effects.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to improve the emission luminance and working characteristics of a phosphor which emits light when excited by vacuum ultraviolet rays.

[0007]

SUMMARY OF THE INVENTION The present inventors have thought that by blocking or protecting the surface of the phosphor particles from the above-mentioned inhibiting factors, it is possible to prevent a decrease in the luminance of the phosphor, As a result of intensive studies, it was found that by coating the surface of the phosphor particles with a boric acid-based compound as a protective substance, the emission luminance and working characteristics when the phosphor was mounted on the device were significantly improved, and the present invention was completed. It led to.

That is, in the phosphor of the present invention, the boric acid compound is boron (B) on the phosphor particle surface as 0.001 parts by weight per 100 parts by weight of the phosphor.
It is characterized by being coated by 10 parts by weight.

The phosphors targeted by the present invention include phosphors which are basically fired in a reducing atmosphere.
It is effective when applied to an aluminate phosphor activated by at least one activator. In particular, BaMg2Al16O27: E activated with divalent europium
It is effective for u phosphor.

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 or ammonium borate is dissolved to prepare a slurry, and drying the slurry. By baking at a temperature of 300 to 1000 ° C., thereby coating the phosphor particle surface with a boric acid compound.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

<Coating amount of boric acid compound> FIG. 1 shows the relative emission intensity of the BaMg2Al16O27: Eu phosphor coated with the boric acid compound when excited by vacuum ultraviolet light at 147 nm using a vacuum ultraviolet spectrophotometer, and the coating of the boric acid compound. Plots were made for quantity relationships. Here, the coating amount of the boric acid compound is represented by an analysis value of boron (B). In the figure, the solid line shows the case where the phosphor was baked in air at 450 ° C. for 30 minutes, and the broken line shows the phosphor which was not baked. From the broken line, the relative luminance tends to decrease, though slightly with the amount of the boric acid-based compound attached, and the relative luminous intensity is about 95% when the amount is 0.1 parts by weight.

As described above, baking is performed for the purpose of using a light emitting device such as a plasma display in order to remove a binder used when forming a phosphor layer. Therefore, the relative light emission intensity of the phosphor when mounted on an actual light emitting device is similar to the case where baking is performed by the solid line.

The curve of the baked phosphor shown by the solid line has a relative emission intensity as low as about 60% when the boron analysis value is about 0.0001 parts by weight, but the emission luminance is improved as the amount of boric acid is increased. The relative luminous intensity of the phosphor coated with 01 parts by weight exceeds 90%. Those coated with 0.01 parts by weight or more almost overlap the solid line without baking, and the effect of baking is no longer seen by coating with the boric acid compound. In other words, it can be said that there is no reduction in luminance due to baking.

As shown in FIG. 1, in view of the 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. Yes, it is preferable to coat in the range of 0.01-5 parts by weight. If the boron coating amount is less than 0.001, no effect is recognized, and if it is more than 10 parts by weight, the luminance is significantly reduced and is not suitable for practical use.

FIG. 2 shows an example of a structure obtained by using a vacuum ultraviolet spectrophotometer.
A plot was made of the relationship between the relative emission intensity at the time of excitation of 47 nm vacuum ultraviolet light and the amount of boric acid compound coated. In the figure, the solid line is BaMg2Al1 baked at 450 ° C. for 30 minutes.
6O27: shows a Eu phosphor, and the broken line shows the phosphor as Kr-
Xe-He mixed gas is set in a glass tube filled with 4 torr, arc-discharged at a current of 1.2 A and a voltage of 130 V for 1 hour, and phosphors whose surfaces have been deteriorated are shown.

FIG. 2 shows that the phosphor having the boric acid compound adhered to the particle surface shows Kr-Xe-
The deterioration rate of the He mixed gas by the discharge tube is small. However, if the amount of the boric acid-based compound increases, the relative emission intensity decreases. Therefore, it is practically necessary to set the coating amount to less than 10 parts by weight as B with respect to 100 parts by weight of the phosphor.

As boric acid compounds, Ba, Ca, S
It is also possible to use metal borates such as r, Mg, Zn, Y, Gd, Lu, Sc, La and the like, but these have a property of absorbing vacuum ultraviolet light which is an excitation source, and the luminance is apt to decrease. Therefore, oxides such as B2O3 and B4O5 which are non-metal salts, or boric acids such as H3BO3, H3B4O7 and HBO2,
Alternatively, an ammonium salt of boric acid is preferably used.

<Method of coating boric acid compound> In order to coat the surface of the phosphor particles with the boric acid compound, first, a predetermined amount of the boric acid compound is mixed with the phosphor. This mixing is preferably performed as homogeneously as possible. This is because it is preferable that the coating of the boric acid compound formed on the surface of the phosphor particles is as uniform as possible. The actual coating is performed by firing in the next step. However, by performing the coating more uniformly in this step, the firing temperature can be set lower, which is preferable.

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 surfaces. can do. As such a water-soluble boric acid compound, B
Oxides such as 2O3 and B4O5, or H3BO3 and H3B4O
7, boric acids such as HBO2, or ammonium salts of boric acids.

Among these boric acid compounds, those having a low solubility do not dissolve in a required amount of a predetermined amount of water, and some or most of them adhere to the particle surface of the phosphor in the form of particles. The higher the particle size, the smaller the particle size, the more the phosphor particles can be coated on the surface of the phosphor particles in a small amount. Therefore, the particle size of the boric acid compound adhering to the surface of the phosphor particles is preferably about 0.1 μm or less.

<Baking temperature> The boric acid compound uniformly coated on the phosphor surface is further calcined at a temperature of 300 to 1000 ° C. The calcining of the boric compound at a high temperature causes the phosphor particles to have a glassy surface. Is formed, and the optical transparency of the coating is improved, and at the same time, the coating is chemically and physically stabilized. If the firing temperature is lower than 300 ° C., the coating of the boric acid compound does not sufficiently diffuse to 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 material diffuses into the phosphor particles, deteriorating the phosphor, losing the effect of vitrifying the surface with boric acid, and conversely, lowering the emission luminance of the phosphor. I do. Therefore, the firing temperature is more preferably in the range of 600 to 900C. Most preferred is around 800 ° C. As described above, it is preferable that the firing temperature is as low as possible for the phosphor matrix, but the lower the temperature, the more the above-mentioned effect of the glass is reduced. Therefore, it is effective at a low temperature to attach the boric acid compound as uniformly as possible to the surface of the phosphor particles in the previous step.

<Firing Atmosphere> When firing at a relatively low temperature in the range of 300 to 500 ° C., the firing atmosphere may be air, but when firing at a relatively high temperature in the range of 500 to 1000 ° C., N 2, Ar Or a weak reducing atmosphere such as an N2-H2 mixed gas atmosphere or a CO2-CO mixed gas atmosphere.

[0023]

The ultraviolet light used for the excitation light emission of the phosphor is mainly 365 nm from a high-pressure mercury lamp, 253.7 nm obtained from a low-pressure mercury vapor discharge with high efficiency, 184.9 nm partially radiated from the discharge, xenon discharge. There is 147 nm ultraviolet light emitted from the ultraviolet ray, but the shorter the wavelength of the ultraviolet light, the smaller the transmission power, and conversely, the longer the wavelength of the ultraviolet light, the larger the transmission power. That is, 184.9 nm or 1
Excitation by vacuum ultraviolet light such as 47 nm is relatively near the surface of the phosphor. On the other hand, by baking, it is oxidized near the surface of the phosphor, and is not necessarily oxidized to the inside of the phosphor. Therefore, those that emit light by excitation with vacuum ultraviolet rays are more susceptible to oxidation due to baking. In other words, the vacuum ultraviolet ray excited phosphor can significantly improve the phosphor performance by improving the baking.

Therefore, the present invention works effectively because
The activator is Eu²⁺, Mn²⁺, Ce³⁺, Tb³⁺, Sb³⁺,
Or Sn²⁺Is a phosphor. Only easily oxidized
Is also a phosphor that efficiently excites and emits light with vacuum ultraviolet light.
You. As such a phosphor, BaMg2Al16O27:
Eu, BaMg2Al16O27: Eu, Mn, Sr4Al14
O25: Eu, Zn2SiO4: Mn, LaPO4: Ce,
Tb, MgAl11 O19: Ce, Tb, Y2 SiO5: T
b, etc. Among them, especially Eu²⁺Or Mn ²⁺To
It is effective against aluminate-hydrochloric acid phosphor as activator.
You.

[0025]

EXAMPLE An example of the present invention will be described with reference to BaMg2Al16O27: Eu which is one of aluminate phosphors activated with divalent europium.

First, this phosphor can be manufactured as follows by a method conventionally performed conventionally. The following materials were weighed, and BaCO3 0.90 mol 3MgCO3 Mg (OH) 2 3H2O 0.50 mol γ-Al2O3 8.00 mol Eu2O3 0.05 mol For 100 parts by weight of the total amount, 1.0 parts by weight of Al
Add F3 and ball mill mix in magnetic pot.

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 baked at 1500 ° C. for 8 hours in a reducing atmosphere of N 2 -H 2. After cooling, the mixture was subjected to a dispersion treatment, passed through a 300-mesh sieve, and then dehydrated and dried.

The obtained phosphor is BaMg2Al16O27:
It emits blue light when excited by 147 nm ultraviolet light with a composition of Eu0.1. (Hereinafter referred to as BAM phosphor)

[Example 1] BAM phosphor 100 obtained
Then, 0.1 g of H3BO3 and 100 g of water were added and mixed to obtain a slurry, and then dried at 100 ° C. After drying, the mixture was filled in an alumina crucible and placed in air at 400 ° C. using an electric furnace.
After calcination for a time, the phosphor of the present invention was obtained. According to the result of the chemical analysis of the phosphor, boron was added in an amount of 0.01 to 100 parts by weight of the phosphor.
It was 7 parts by weight.

Example 2 H3 was added to 100 g of the BAM phosphor.
0.5 g of BO3 and 100 g of water were added, and the same operation as in Example 1 was performed to obtain a phosphor of the present invention. According to the result of chemical analysis of the phosphor, boron was added in an amount of 0.1 to 100 parts by weight of the phosphor.
085 parts by weight.

Example 3 H3 was added to 100 g of the BAM phosphor.
2.5 g of BO3 and 100 g of water were added, and the same operation as in Example 1 was performed to obtain a phosphor of the present invention. According to the result of chemical analysis of the phosphor, boron was added in an amount of 0.1 to 100 parts by weight of the phosphor.
43 parts by weight.

Example 4 H3 was added to 100 g of the BAM phosphor.
12.5 g of BO3 and 100 g of water were added, and the same operation as in Example 1 was performed to obtain a phosphor of the present invention. According to the result of chemical analysis of the phosphor, boron was 2.1 parts by weight based on 100 parts by weight of the phosphor.

[Example 5] H3 was added to 100 g of the BAM phosphor.
25.0 g of BO3 and 100 g of water were added, and the same operation as in Example 1 was performed to obtain a phosphor of the present invention. According to the result of chemical analysis of the phosphor, boron was 4.3 parts by weight based on 100 parts by weight of the phosphor.

Example 6 1 g of ammonium borate and 100 g of water were added to 100 g of a BAM phosphor, mixed, slurried, and dried. After drying, the mixture was filled in an alumina crucible and fired at 800 ° C. for 1 hour in an H 2 —N 2 atmosphere to obtain a phosphor of the present invention. According to the result of the chemical analysis of the phosphor, boron was 0.14 part by weight based on 100 parts by weight of the phosphor.

Example 7 100 g of BAM phosphor was added to 50
0 g of water was added with 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. 34g
After the dropwise addition, the pH is adjusted to 8 by adding aqueous ammonia. After allowing to stand for 1 hour, it was sufficiently washed with water while being dehydrated and dried 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 based on 100 parts by weight of the phosphor.

Comparative Example 1 H3 as used in this example
A phosphor that does not coat the phosphor particle surface with a boric acid compound such as BO3 at all is selected. That is, the phosphor before the coating treatment of the phosphor of Examples 1 to 7 is performed.

[Comparative Example 2] A phosphor obtained by baking and mixing a boric acid-based compound in the raw material of the phosphor instead of coating the particle surface of the phosphor was prepared as follows.

The following are weighed as raw materials, and BaCO3 0.90 mol 3MgCO3.Mg (OH) 2.3H2O 0.50 mol γ-Al2O3 8.00 mol Eu2O3 0.05 mol All of these are 100 parts by weight. To 1.0 parts by weight of Al
Add 0.1 parts by weight of H3BO3 in addition to F3 and mix in a ball mill in a magnetic pot. BAM before coating with boric acid compound used in the above Examples 1 to 7
Manufactured in the same manner as the phosphor.

5 g of the BAM phosphor obtained in each of Examples 1 to 7 and Comparative Examples 1 and 2 was packed in a magnetic crucible and baked at 450 ° C. for 30 minutes using an electric furnace. The gas discharge tube was tested. Table 1 shows the results. The luminous intensity maintenance ratio was calculated as luminous intensity after baking / luminous intensity before baking × 100%.

[0040]

[Table 1]

[0041]

As described above, by coating the surface of the phosphor particles with the boric acid compound, deterioration of the phosphor due to oxidation during baking is prevented, and deterioration due to ion bombardment in the discharge space is also prevented. be able to. That is,
By using the phosphor of the present invention, the luminance of a light emitting device such as a color plasma display panel or a xenon discharge fluorescent lamp utilizing ultraviolet light, in particular, 147 nm vacuum ultraviolet light of xenon is improved, and the working characteristics are improved. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing the relationship between the relative emission intensity upon excitation of 147 nm vacuum ultraviolet light and the amount of boric acid compound coated (solid line after baking, broken line before baking).

FIG. 2 is a characteristic diagram showing a relationship between a relative emission intensity at the time of excitation of 147 nm vacuum ultraviolet ray and a coating amount of a boric acid compound (a solid line is before deterioration of a discharge tube, and a broken line is after deterioration).

Claims (3)

[Claims] 1. A phosphoric acid compound comprising boron (B) as a boron compound (B) on a phosphor particle surface in an amount of 0.001 to 100 parts by weight based on 100 parts by weight of the phosphor.
A vacuum ultraviolet-excited light-emitting phosphor, which is coated by 10 parts by weight. 2. The VUV-excited phosphor according to claim 1, wherein the phosphor is an aluminate phosphor activated by at least one activator of Eu and Mn. . 3. A slurry is prepared by mixing a phosphor with water in which at least one boric acid compound selected from boric acid, boron oxide and ammonium borate is dissolved, to prepare a slurry, and drying the slurry; A method for producing a vacuum ultraviolet-excited light-emitting phosphor, characterized in that the surface of the phosphor particles is coated with a boric acid-based compound by firing at a temperature of up to 1000C.