JPH09221666A - Red emitting phosphor and fluorescent lamp - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To form a thin and uniform phosphor layer, which has good dispersibility in forming a phosphor layer, and has high initial emission intensity.
In addition to providing a red light emitting phosphor with little deterioration in emission intensity during lighting, by using this phosphor, a fluorescent lamp with little deterioration in emission chromaticity and emission intensity over time and a high luminous flux maintenance factor is provided. A general formula _{(Y 1-x Eu x)} 2 O 3 ( where 0.
01 ≦ x ≦ 0.20), and a coating layer made of a polyethylene polyoxypropylene condensate is formed on the surface of the europium-activated yttrium oxide phosphor. The weight ratio of the coating layer composed of polyethylene polyoxypropylene condensate is in the range of 0.01 to 0.5% by weight, more preferably 0.1 to 0.3% by weight, based on the europium-activated yttrium oxide phosphor. Is desirable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a red-emitting phosphor and a fluorescent lamp using the same, and in particular, it has good dispersibility when forming a phosphor layer, and has high initial emission intensity and lighting. TECHNICAL FIELD The present invention relates to a red light-emitting phosphor having less deterioration in emission intensity and a fluorescent lamp using the phosphor to suppress deterioration of emission chromaticity and emission intensity over time and improve a luminous flux maintenance factor.

[0002]

As is well known, since europium-activated yttrium oxide phosphor (Y ₂ O ₃ : Eu) has excellent phosphor characteristics such as emission brightness and emission color by electron beam or ultraviolet excitation, It is widely used as a red component phosphor for color cathode ray tubes and a red component phosphor for three wavelength emission type fluorescent lamps.

Further, for the purpose of improving the luminous efficiency of the europium-activated yttrium oxide phosphor as described above, studies have been made so far to add fluxes made of various compounds. A specific example of this flux is, for example, JP-A-55.
Alkaline earth metal borate as disclosed in JP-A-161883, lithium phosphate as disclosed in JP-B-55-161883, and JP-A-58-52382.
Aluminum phosphate as described in JP-A-55-152248, aluminum borate as disclosed in JP-A-55-152248, barium borate as disclosed in JP-A-59-45384, and JP-A-58. Compounds such as alkaline earth metal oxides disclosed in JP-A-127777 and barium fluoride / magnesium fluoride disclosed in JP-A-61-266488 have been proposed as fluxing agents.

By adding these fluxes to the phosphor, it becomes possible to grow crystals of the phosphor particles to a large extent, and it is also possible to control the shape of the phosphor particles to be round and uniform to some extent. . As a result, the initial luminous efficiency of the fluorescent lamp using such a phosphor can be improved.

[0005]

However, the conventional (Y _1-x Eu _x ) ₂ O ₃ phosphor has a powdery property that it has a relatively strong aggregating action and forms a phosphor layer. At that time, the uniform dispersibility in the binder tended to be poor. On the other hand, when the crystal shape of the red light emitting phosphor is made uniform, the dispersibility tends to deteriorate rather. Therefore, in the organic solvent such as butyl acetate or xylene or the water-soluble binder such as polyethylene oxide, the above (Y
_1-x Eu _x ) ₂ O ₃ phosphor is dispersed, and a binder is further added to form a phosphor slurry. When this phosphor slurry is applied to the inner wall surface of a glass tube (glass bulb), the phosphor The dispersibility and elongation of the phosphor are poor, the surface of the phosphor layer (phosphor film) becomes rough or uneven, and the compatibility with the inner surface of the glass tube is poor. In any case, make the phosphor layer uniform. There was a problem that became difficult.

In particular, when manufacturing an annular fluorescent lamp, it is necessary to bend the glass tube after applying the phosphor slurry, and when the phosphor layer is non-uniform, the phosphor layer is not formed. It may crack, peel off or fall off,
There is a problem that the surface of the phosphor layer becomes shark-skin and the luminous flux maintenance factor of the fluorescent lamp decreases.

The present invention has been made in order to solve the above-mentioned problems, and has good dispersibility when forming a phosphor layer, a thin and uniform phosphor layer can be formed, and initial light emission is also possible. By providing a red light-emitting phosphor having high intensity and little deterioration in emission intensity during lighting, and by using this phosphor, a fluorescent lamp with little deterioration in emission chromaticity and emission intensity over time and a high luminous flux maintenance factor can be provided. The purpose is to provide.

[0008]

In order to improve the dispersibility of the europium-activated yttrium oxide phosphor and to prevent the deterioration over time, the present inventor attaches various compounds to the phosphor surface and The effects of type and amount of adhesion on the lamp characteristics were compared and examined by experiments.

As a result, in particular, a polyethylene polyoxypropylene condensate is added to the (Y _1-x Eu _x ) ₂ O ₃ phosphor powder for surface treatment to form a coating layer of the condensate on the phosphor surface. It has been found that, as a result, the dispersibility of the phosphor and the uniformity of the phosphor layer are improved, and deterioration of the emission intensity of the phosphor over time can be more effectively prevented. In particular, the dispersibility of the phosphor is improved, and the agglomeration action of the phosphor powder is effectively suppressed when forming the phosphor layer. Therefore, a small amount of binder works effectively without increasing the thickness of the phosphor layer or increasing the amount of binder added.
It was found that a thin phosphor layer having excellent uniformity can be obtained. The present invention has been completed based on the above findings.

That is, the red light emitting phosphor according to the present invention is
General formula (Y _1-x Eu _x ) ₂ O ₃ (where 0.01 ≦ x ≦
0.20), a coating layer made of polyethylene polyoxypropylene condensate is formed on the surface of the europium-activated yttrium oxide phosphor.

The fluorescent lamp according to the present invention has the general formula (Y _1-x Eu _x ) ₂ O ₃ (where 0.01 ≦ x ≦ 0.2
In a glass tube, a mixture of a red-emitting phosphor having a coating layer made of a polyethylene polyoxypropylene condensate formed on the surface of the europium-activated yttrium oxide phosphor represented by 0), a blue-emitting phosphor, and a green-emitting phosphor is placed in a glass tube. It is characterized in that it has a phosphor layer formed by applying it to a wall surface and baking it.

Further, the weight ratio of the coating layer composed of polyethylene polyoxypropylene condensate is 0.01 to 0.5% by weight, more preferably 0.1 to 0.3% by weight based on the europium-activated yttrium oxide phosphor. It is good to set it in the range of%.

Further, the shape of the glass tube is annular.

Here, the europium-activated yttrium oxide phosphor ((Y _1-x Eu _x ) ₂ O ₃ ) is a phosphor that emits red light when irradiated with an electron beam or ultraviolet rays,
Used as a red component phosphor for a three-wavelength emission type fluorescent lamp.

Eu (europium) acts as an activator (activator) for enhancing the luminous efficiency of the phosphor, and is added in an atomic ratio of 0.01 to 0.20 with respect to Y (yttrium). If the addition ratio is less than 0.01, the effect of improving the luminous efficiency is small. On the other hand, if the addition ratio exceeds 0.20,
Coloring is likely to occur and the luminous efficiency of the lamp is rather impaired.

The polyethylene polyoxypropylene condensate forming the coating layer is a substance that improves the dispersibility of the phosphor and suppresses the aggregation action of the phosphor to form a uniform phosphor layer. By forming this coating layer on the surface of the phosphor powder, the binder works effectively even when a small amount of the binder is used, and a thin phosphor layer with good uniformity is formed on the inner wall surface of the glass bulb. be able to.

The polyethylene polyoxypropylene condensate constituting the coating layer is preferably added in an amount of 0.01 to 0.5% by weight based on the europium-activated yttrium phosphor. The addition amount of the condensate is 0.
When the amount is less than 01% by weight, the effect of improving the dispersibility of the phosphor and preventing the deterioration is insufficient, and the effect of improving the emission characteristics of the phosphor and the uniformity of the phosphor layer is small.
On the other hand, when the amount of the condensate added exceeds 0.5% by weight, the condensate tends to slightly remain in the phosphor layer even after firing in the lamp manufacturing process, and the luminous flux maintenance factor of the lamp decreases. I will end up.

The red-emitting phosphor according to the present invention is manufactured, for example, according to the following operating procedure. That is, the above-mentioned general formula (Y _1-x Eu _x ) ₂ O whose composition is adjusted stoichiometrically
₃ (provided that 0.01 ≦ x ≦ 0.20), a predetermined amount of polyethylene polyoxypropylene condensate was weighed with respect to the europium-activated yttrium oxide phosphor, and a slurry in which this condensate was dispersed was used. It is manufactured by subjecting the phosphor powder to a surface treatment, filtering and drying the powder, and sieving the dried product.

Further, in the fluorescent lamp according to the present invention, the red light emitting phosphor prepared as described above, another blue light emitting phosphor and a green light emitting phosphor are mixed in a mixing ratio such that a predetermined color temperature is obtained, Further, the obtained mixture is uniformly dispersed in a binder in which polyethylene oxide or the like is dissolved to obtain a phosphor slurry, and the phosphor slurry is applied to the inner wall surface of the glass tube (bulb), dried and fired to form a light emitting layer. It is manufactured according to a normal lamp manufacturing process in which the (phosphor layer) is integrally formed.

At the stage where the phosphor slurry is applied to the inner wall surface of the glass tube, the phosphor slurry has a good elongation, a thin coating film having a uniform thickness and no agglomerates is formed. By baking this coating film together with the glass tube, the condensate component is completely burned, and a uniform phosphor layer having a predetermined composition is formed.

According to the red light emitting phosphor and the fluorescent lamp having the above structure, the coating layer made of polyethylene polyoxypropylene condensate is integrally formed on the surface of the (Y _1-x Eu _x ) ₂ O ₃ phosphor. Therefore, the dispersibility of the phosphor when forming the phosphor layer is good, a thin phosphor layer with excellent uniformity is formed with less occurrence of aggregates, and deterioration of the phosphor over time is effective. And a red light-emitting phosphor that exhibits high emission brightness can be obtained.

Further, by using this red light emitting phosphor as a red light emitting component of a three-wavelength light emitting fluorescent lamp or the like, it is possible to realize a fluorescent lamp exhibiting a high light emission luminance and a high luminous flux maintenance factor.

Furthermore, since the dispersibility of the phosphor particles is good and a thin phosphor layer having excellent uniformity is obtained, even when the glass tube on which the phosphor layer is formed is bent into an annular shape, the fluorescence is reduced. It is possible to mass-produce a ring-shaped fluorescent lamp having excellent lamp characteristics, which is less likely to cause cracks in the body layer, peeling, or falling off, and has a high manufacturing yield.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described.
This will be described more specifically with reference to the following examples.

Example 1 and Comparative Example 1 0.94 mol of Y ₂ O ₃ and 0.06 mol of Eu ₂ O ₃ powder were weighed, and these powders were sufficiently ground and mixed by a ball mill to obtain a powder. The mixture thus obtained was placed in a crucible and baked in air at a temperature of 1100 ° C. for 3 hours. After adding and mixing 0.3 mol of barium borate as a fluxing agent to 1 mol of the oxide raw material to the obtained fired product, the temperature was 1250.
By firing at 0 ° C., pulverizing the obtained fired product, and further washing with water, a phosphor for Example 1 having a composition of (Y _0.94 Eu _0.06 ) ₂ O ₃ was prepared.

Next, the prepared phosphor is suspended in water to form a phosphor slurry, which is 0.3% by weight based on the weight of the phosphor.
The red-light-emitting fluorescence according to Example 1 in which the coating layer made of the above-mentioned condensate was formed by adding the polyethylene polyoxypropylene condensate of 1. to the phosphor slurry, stirring for 15 minutes to perform surface treatment, and then drying. The body was prepared.

Next, a coating solution was prepared by suspending the above red-light-emitting phosphor in a binder solution, coated on the inner surface of the glass tube and dried. Then, as shown in FIG. 1, a temperature of 400
The phosphor layer 2 is adhered to the inner surface of the glass tube 1 by firing at ℃, and the glass tube is further heated to a temperature of 600 ℃ or more and bent into an annular shape.
A ring-shaped fluorescent lamp according to Example 1 as shown in FIG.

On the other hand, in Example 1, the surface treatment using the polyethylene polyoxypropylene condensate was not carried out, and the coating layer made of the condensate was not formed (Y _0.94 Eu).
_A ring-shaped fluorescent lamp according to Comparative Example 1 having the same dimensions was manufactured by the same procedure as in Example 1 except that a _0.96 ) ₂ O ₃ phosphor was used.

Examples 2 to 5 In Example 1, as shown in Table 1, the amount of polyethylene polyoxypropylene condensate added was changed to a range of 0.01 to 0.7% by weight based on the weight of the phosphor. Except for the points, the surface treatment of the phosphor was performed under the same conditions as in Example 1 to manufacture the ring-shaped fluorescent lamps according to Examples 2 to 5, respectively.

With respect to the fluorescent lamps according to Examples 1 to 5 and Comparative Example 1 thus manufactured, the initial emission intensity a immediately after the production was measured, and the emission intensity b after 1000 hours of lighting was respectively measured, and the emission intensity ratio was further measured. The luminous flux maintenance factor represented by (b / a) was calculated, and the results shown in Table 1 were obtained. Note emission intensity according to Comparative Example 1 not to surface treatment with polyethylene polyoxypropylene condensate _{(Y 0.94 Eu 0.06) 2 O} 3 phosphor reference value an initial emission intensity of the fluorescent lamp using (100% ) Is shown relatively.

[0031]

[Table 1]

As is clear from the results shown in Table 1, the initial emission intensity of the fluorescent lamps of the examples is the reference value (the standard value of the fluorescent lamp of the comparative example 1 not surface-treated with the polyethylene polyoxypropylene condensate). (100%), the relative value was 100.2 to 100.7%, and it was found that the luminous efficiency was improved.

The emission intensity after 1000 hours of lighting was 84 in the fluorescent lamp of Comparative Example 1 showing the conventional example.
%, Whereas in the examples, 86.5-91.
This is an improvement of 6%, and the deterioration of the emission intensity over time is reduced. That is, when comparing the luminous flux maintenance factors, 0.84 is obtained in Comparative Example 1, while it is 0.8 in Example.
It has improved to 86 to 0.91. That is, it was found that by using the phosphor powder surface-treated with the condensate, it is possible to obtain a fluorescent lamp having both improved initial light emission intensity and luminous flux maintenance factor.

Further, the fluorescent lamps of the respective examples are improved in appearance as compared with the lamp of Comparative Example 1. 2 and 3 are partial cross-sectional views showing the glass tube inner wall portion according to Example 1 and Comparative Example 1 in an enlarged manner, respectively. As shown in FIG. 2, in the fluorescent lamp of each example, the phosphor layer 2
No defects such as cracks and shark skin of a were observed, and glass tube 1
The phosphor layer 2a was uniformly formed on the inner wall surface of a.

On the other hand, as shown in FIG. 3, in the fluorescent lamp according to Comparative Example 1, since the surface treatment with the condensate is not carried out, the dispersibility of the phosphor is deteriorated and the fluorescent lamp is formed on the inner wall surface of the glass tube 1b. In addition, many aggregated portions were formed on the phosphor layer 2b.

Examples 6 to 8 and Comparative Examples 2 to 4 A red light emitting phosphor powder according to Example 1 obtained by performing a surface treatment using a polyethylene polyoxypropylene condensate and a blue light emitting phosphor. (Sr, Ca, B
a, Eu) ₁₀ (PO ₄ ) ₆ Cl ₂ phosphor powder and (La, Ce, Tb) PO ₄ phosphor powder as a green-emitting phosphor have relative color temperatures of respectively as shown in Table 2. 29
The three-wavelength type mixed phosphors for Examples 6 to 8 were respectively prepared by uniformly mixing at a mixing ratio of 00, 5000, 6500 ° C.

On the other hand, except that the red light emitting phosphor powder not subjected to the surface treatment with the condensate was used, the mixture treatment with the blue and green light emitting phosphor powders was carried out in the same manner as in Examples 6 to 8 to obtain Examples 6 to 8. Three-wavelength mixed phosphors according to corresponding Comparative Examples 2 to 4 were prepared.

Next, each three-wavelength type mixed phosphor is uniformly dispersed in a binder to form a phosphor slurry, and this phosphor slurry is applied to the inner surface of the glass tube (glass bulb) 1 as shown in FIG. After the phosphor layer 2 is formed by drying and baking, the electrodes 3 for discharge and the caps provided with sockets are attached to both ends of the glass tube in accordance with the ordinary lamp manufacturing process. Example 6
8 and the ring-shaped fluorescent lamps according to Comparative Examples 2 to 4 were manufactured.

Regarding the ring-shaped fluorescent lamps according to Examples 6 to 8 and Comparative Examples 2 to 4 thus manufactured, Examples 1 to 5 were used.
Similarly to the above, the initial emission intensity immediately after production was measured, the emission intensity after 1000 hours of lighting was measured, and the luminous flux maintenance factor was calculated to obtain the results shown in Table 2 below.

The emission intensity shown in Table 2 is based on the initial emission intensity of the fluorescent lamps according to Comparative Examples 2 to 4 formed by using the europium-activated yttrium oxide phosphor which is not surface-treated with the condensate. It was displayed relatively as 100%).

[0041]

[Table 2]

As is clear from the results shown in Table 2, the initial emission intensities of the fluorescent lamps according to Examples 6 to 8 were as follows: Lamp as standard value (100%)
The relative value was 100.3 to 100.5%, and it was found that the luminous efficiency was improved.

The emission intensity after 1000 hours of lighting is 86.1 to 87.7% in the fluorescent lamps of Comparative Examples 2 to 4 showing the conventional example, whereas it is 91.2 to 92 in the Examples. It was improved to 0.5%, and the deterioration of emission intensity over time was reduced. That is, comparing the luminous flux maintenance factors, 0.86 to 0.88 in Comparative Examples 2 to 4, while 0.91 to 0.9 in Examples 6 to 8.
It has improved to 2. That is, it was found that by using the phosphor powder surface-treated with the condensate, it is possible to obtain a fluorescent lamp having both improved initial light emission intensity and luminous flux maintenance factor.

Even when the three-wavelength type mixed phosphor is used as in Examples 6 to 8, the luminous efficiency and the red light emitting phosphor are used as the monochromatic component as in Examples 1 to 5, respectively. The effect of improving the luminous flux maintenance factor was obtained.

When the tube end color difference of the fluorescent lamps according to Examples 6 to 8 was measured, the average value was 0.0011.
Average value of tube end color difference of the fluorescent lamps of Comparative Examples 2 to 0.00
It was reduced to half that of No. 24, and it was confirmed that the effect of improving the tube end color difference was also exhibited. This is considered to be due to the fact that a uniform phosphor layer was obtained by using the phosphor surface-treated with the condensate.

[0046]

As described above, according to the red light emitting phosphor and the fluorescent lamp of the present invention, (Y _1-x Eu _x ) ₂
Since the coating layer made of polyethylene polyoxypropylene condensate is integrally formed on the surface of the O ₃ phosphor, the dispersibility of the phosphor at the time of forming the phosphor phase is good, and the occurrence of aggregated particles is small. A thin phosphor layer having excellent uniformity is formed, deterioration of the phosphor over time can be effectively prevented, and a red-emitting phosphor exhibiting high emission brightness can be obtained.

Further, by using this red light emitting phosphor as a red light emitting component of a three-wavelength light emitting type fluorescent lamp or the like, it is possible to realize a fluorescent lamp exhibiting a high light emission luminance and a high luminous flux maintenance factor.

Furthermore, since the dispersibility of the phosphor particles is good and a thin phosphor layer having excellent uniformity is obtained, even when the glass tube on which the phosphor layer is formed is bent into an annular shape, the fluorescence is reduced. It is possible to mass-produce a ring-shaped fluorescent lamp having excellent lamp characteristics, which is less likely to cause cracks in the body layer, peeling, or falling off, and has a high manufacturing yield.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a fluorescent lamp using a red light emitting phosphor according to the present invention.

FIG. 2 is a partial cross-sectional view showing an enlarged inner wall portion of the glass tube of the fluorescent lamp according to the first embodiment.

FIG. 3 is a partial cross-sectional view showing an enlarged inner wall portion of a glass tube of a fluorescent lamp according to Comparative Example 1.

[Explanation of symbols]

 1 Glass tube (glass bulb) 2, 2a, 2b Phosphor layer (fluorescent film) 3 Electrode

Claims (6)

[Claims] 1. A europium-activated yttrium oxide phosphor represented by the general formula (Y _1-x Eu _x ) ₂ O ₃ (where 0.01 ≦ x ≦ 0.20) is formed on the surface of a polyethylene polyoxypropylene condensate. A red-emitting phosphor having a coating layer formed thereon. 2. The weight ratio of the coating layer made of polyethylene polyoxypropylene condensate is 0.01 to 0.5% by weight based on the europium-activated yttrium oxide phosphor. Red emitting phosphor. 3. The weight ratio of the coating layer made of a polyethylene polyoxypropylene condensate is 0.1 to 0.3% by weight based on the europium-activated yttrium oxide phosphor. Red emitting phosphor. 4. A europium-activated yttrium oxide phosphor represented by the general formula (Y _1-x Eu _x ) ₂ O ₃ (where 0.01 ≦ x ≦ 0.20) is formed on the surface of a polyethylene polyoxypropylene condensate. A fluorescent lamp having a phosphor layer formed by coating a mixture of a red-emitting phosphor having a coating layer, a blue-emitting phosphor, and a green-emitting phosphor on an inner wall surface of a glass tube and firing the mixture. 5. The weight ratio of the coating layer made of a polyethylene polyoxypropylene condensate is 0.01 to 0.5% by weight based on the europium-activated yttrium oxide phosphor. Fluorescent lamp. 6. The fluorescent lamp according to claim 4, wherein the glass tube has an annular shape.