JP2000226575A - Blue-color fluorescent material for three-wavelength fluorescent lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject fluorescent material substantially freed from decline in luminous efficiency or change in luminescent color due to baking in the production of fluorescent lamps. SOLUTION: This blue-color fluorescent material consists of an aluminate of the compositional formula MiMgAljOn: Euk (M is Ba and/or Sr; 1.2<=i<=2.7; 14.5<=j<=35.5; 0.01<=k<=0.50; 23.9<=n<=57.5); wherein n is such a value as to be unequivocally determined from the respective valences of the oxygen atom and the other atoms constituting the aluminate, and calculated by the formula: (2i+3j+2k+2)/2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue phosphor for a three-wavelength fluorescent lamp. More specifically, the present invention relates to a novel blue phosphor having no or drastic decrease in luminous efficiency or color change due to baking during the lamp manufacturing process. The present invention relates to a blue phosphor for a wavelength fluorescent lamp.

[0002]

2. Description of the Related Art Aluminate phosphors have been put into practical use as energy-saving phosphors for three-wavelength fluorescent lamps. For example, as a blue phosphor, BaMg ₂ Al ₁₆ O ₂₇ : Eu
²⁺ , SrMgAl ₁₀ O ₁₇ : Eu ²⁺ or BaMg
Al ₁₀ O ₁₇ : Eu ²⁺ , BaMg ₂ as a green phosphor
Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ , CeMgAl ₁₁ O
_{1 9:} Ce ^{3+, Tb 3+} or BaMgAl ₁₀ O _17: E
u ²⁺ , Mn ^{2+ and the} like (Phosphor Handboo
k, p392, p833, CRC Press LLC). Such a blue phosphor and a green phosphor are used in combination with a red phosphor to produce a white fluorescent lamp.

One of the major problems of such an aluminate phosphor is thermal deterioration due to baking treatment in the lamp manufacturing process. That is, the phosphor used in the lamp is generally mixed with a binder (usually an organic compound) using an organic solvent or water as a solvent, applied to a predetermined portion, and then burned to remove the binder by 400 to 700.
Heat treatment is carried out at a temperature of ° C. This treatment causes a decrease in the luminous efficiency and a change in the luminescent color of the obtained phosphor.

[0004] As measures against the thermal degradation phenomenon of the aluminate phosphor, attempts have been made to lower the heating temperature and to select an effective binder material, but this has not been a fundamental solution.
As a measure against thermal degradation from the side of the phosphor, a method of coating the surface of the phosphor with a stable substance has been proposed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a new type of aluminate three-wavelength fluorescent lamp in which a decrease in luminous efficiency or a change in luminescent color due to baking during the manufacture of the fluorescent lamp is eliminated or drastically reduced. It is to provide a blue phosphor.

[0006]

SUMMARY OF THE INVENTION The present inventor has proposed a
Aluminate blue phosphor, for example, BaMg _Two
Al₁₆O₂₇: Eu²⁺, SrMgAl₁₀O₁₇: E
u²⁺Or BaMgAl₁₀O₁₇: Eu²⁺Different from
Have different compositions and different crystal structures.
Thermal phenomena caused by baking
New types of aluminate phosphors were found.

[0007] Thus, the present invention provides a composition of formula M _i MgA
l _j O _n: Eu aluminate (M represented by _k is Ba and / or Sr, 1.2 ≦ i ≦ 2.7,14.5 ≦ j ≦ 35.5,0.
01 ≦ k ≦ 0.50, 23.9 ≦ n ≦ 57.5). A blue phosphor for a three-wavelength fluorescent lamp is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphor of the present invention has a composition formula of M _i
MgAl _j O _n: Eu aluminate (M represented by _k is Ba and / or Sr, 1.2 ≦ i ≦ 2.7,14.5 ≦ j ≦ 3
5.5, 0.01 ≦ k ≦ 0.50, 23.9 ≦ n ≦ 57.5). However, the value of n relating to the oxygen atom is uniquely determined from the valences of the oxygen atom and other atoms constituting the aluminate, and is specifically calculated by the formula (2i + 2 + 3j + 2k) / 2. .

The present inventor has proposed a blue fluorescent lamp for a three-wavelength fluorescent lamp.
Focused on the deterioration phenomenon caused by baking of the body, repeated research
As a result, BaMg currently used for three-wavelength fluorescent lamps
_TwoAl₁₆O₂₇: Eu²⁺, SrMgAl₁₀O₁₇:
Eu²⁺Or BaMgAl ₁₀O₁₇: Eu²⁺Blue
More barium and / or strontium than phosphor
When the amount of aluminum is increased, the resulting phosphor becomes baked.
The luminous efficiency and the change in luminescent color are significantly reduced even after
I found little.

[0010] The composition formula M _i MgAl _j O _n of the present invention: E
aluminate blue phosphor represented by u _k (M is Ba and / or Sr, 1.2 ≦ i ≦ 2.7,14.5 ≦ j ≦ 35.5,0.01
≦ k ≦ 0.50,23.9 ≦ n ≦ 57.5 ) are currently used in three band fluorescent lamp BaMgAl ₁₀ O _17: have a different crystal structure than the blue phosphor such as Eu ^2+. That is, the aluminate of the present invention is made of BaMgAl ₁₀ O ₁₇ : E
Compared with a conventional aluminate phosphor such as u ²⁺ , the crystal lattice constants a and b are smaller, and clearly show a different structure. This means that, in the X-ray diffraction chart of FIG. 1, for example, the aluminate (upper stage) of the present invention is BaMgAl ₁₀ O whose (110) plane is conventionally known
₁₇ : It can be confirmed from the shift to a higher angle side than Eu ²⁺ (lower).

According to the present invention, the composition formula M_iMgAl_jO
_n: Eu_k(M is Ba and / or Sr, 1.2 ≦ i ≦ 2.
7, 14.5 ≦ j ≦ 35.5, 0.01 ≦ k ≦ 0.50, 23.9 ≦ n ≦ 57.
Baking by adopting phosphor composed of 5)
The detailed reason why the thermal degradation phenomenon caused by
No, but speculated as follows: BaMgAl₁₀O
₁₇: Eu²⁺Aluminate phosphor such as
It has a lumina structure, which is mainly composed of alumina
Spinel block as a skeleton
The conductive layer between the layers is called alkaline earth metal and acid.
A pair of elementary ions is located and the emission center (Eu
²⁺) Is present. Composition formula of the present invention
 M_iMgAl_jO_n: Eu_kAluminate represented by
(M is Ba and / or Sr, 1.2 ≦ i ≦ 2.7, 14.5 ≦
j ≦ 35.5, 0.01 ≦ k ≦ 0.50, 23.9 ≦ n ≦ 57.5)
The phosphor is BaMgAl₁₀O₁₇: Eu²⁺like
Has β-alumina structure similar to aluminate phosphor
Increased due to increased barium and aluminum content
The crystal lattice constant changes and the spinel block and conduction layer
ON arrangement is different. Thereby, the light emission center (Eu
²⁺) Is Eu³⁺Is difficult to oxidize
Or whether the crystal structure itself became more stable
In the case of bright phosphors, thermal degradation due to baking is drastically reduced.
Maybe.

Thus, according to the present invention, it is possible to obtain a blue phosphor for a three-wavelength fluorescent lamp with reduced thermal degradation even by baking in which the binder is removed at 400 to 700 ° C. in an oxidizing atmosphere. In particular, a blue phosphor with a very small change in emission color can be obtained even by baking at 400 to 700 ° C.

The blue phosphor of the present invention may be prepared by mixing raw materials (generally as oxides, carbonates, or hydroxides) of each metal according to a predetermined composition, or, if necessary, by using a reaction accelerator (for example, fluorine). (Aluminum chloride), followed by mixing and baking. At the beginning of firing, one or more firings may be performed in an oxidizing atmosphere, but finally, at 1300 ° C. in an inert gas or reducing atmosphere.
In the above, firing is performed for at least one hour.

The point of producing the blue phosphor of the present invention lies in the compounding ratio of the raw materials and the firing step. By strictly adjusting the compounding ratio of the raw materials and firing under sufficient time and temperature conditions, the desired composition is obtained. Is obtained. Further, the fact that it has a crystal structure different from that of a normal aluminate can be confirmed by, for example, X-ray diffraction.

[0015]

The following examples are provided to further clarify the features of the present invention, but the present invention is not limited by these examples. Example _{1: BaCO 3 1.37mol 4MgCO 3 ·} Mg (OH) 2 · 3H 2 O 0.20mol Al 2 O 3 8.63mol Eu 2 O 3 0.075mol AlF 3 0.27mol

After mixing the raw materials having the above composition, firing (at a maximum temperature of 1600 ° C. for 3 hours, atmosphere: 10 vol% H ₂ /
N ₂ ), pulverize, classify and dry, Ba _1.37 MgAl
_17.26 O _28.41 : Divalent E represented by the composition formula Eu _0.15
A u-activated blue light-emitting barium aluminate phosphor was obtained. For comparison, normal composition (conventional composition) Ba _0.9 MgAl _{1 0}
A phosphor of O ₁₇ : Eu _0.1 was simultaneously produced under the same conditions.
The obtained phosphor and an aluminate phosphor of normal composition (Ba)
One example of an X-ray diffraction chart of _0.9 MgAl ₁₀ O ₁₇ : Eu _0.1 ) is shown in FIG. 1 (measurement conditions: X-ray source to CuKα; tube voltage to 40 kV; tube current to 30 mA; scanning speed to 2).
Degree 2θ / min; scattering slit (SS) to 1 degree; divergence slit (DS) to 1 degree; light receiving slit (RS) to 0.
3 mm). As shown in this X-ray diffraction chart, Ba _1.37 MgAl ₁₇ consisting of the present invention _.26 O _28.41: Eu _0.15
The crystal structure of the phosphor is a normal Ba _0.9 MgAl ₁₀ O
₁₇ : Different from the crystal structure of Eu _0.1 (around 2θ = 31.5 degrees or 33 degrees). Each crystal lattice constant is
Ba _1.37 MgAl _17.26 O _28.41 : a = b = 5 in Eu _0.15 .
With 6155 (6) and c = 22.679 (3), Ba _0.9 MgAl
_A = b = 5.6247 (2) and c = 2 for ₁₀ O ₁₇ : Eu _0.1
2.634 (1).

The obtained phosphor and a normal composition Ba _0.9 MgA
l ₁₀ O _17: phosphor oxidizing atmosphere of Eu _0.1 (atmosphere)
The wafer was kept at 700 ° C. for 30 minutes, and simultaneously baked. The phosphor before and after baking was irradiated with ultraviolet light of 254 nm using a Xe ultraviolet light source, and the emission luminance and emission color were measured. In order to change the luminous efficiency before and after baking, the variation ratio of the ratio between the luminous luminance (Br) and the chromaticity value y was determined. Table 1 shows changes in luminous efficiency before and after baking by excitation at 254 nm.

The rate of change of the luminance / chromaticity y ratio of the phosphor before and after baking is calculated as follows. Fluctuation rate (%) of luminance / chromaticity y ratio = (△ (Br / y) /
(Br / y) 0) × 100 = (((Br / y) t− (Br)
/ Y) 0) / (Br / y) 0) × 100 (Br / y) 0 is the ratio of luminance Br and chromaticity y of the phosphor before baking, and (Br / y) t is baking (at a temperature t ° C.) ) Indicates the ratio between the luminance and the chromaticity y of the phosphor, and when the fluctuation rate (%) = 0, it indicates that the luminous efficiency before and after baking does not change.

As can be seen from Table 1, according to the present invention,
Composition formula M_iMgAl_jO_n: Eu _kAluminum represented by
Phosphate (M is Ba and / or Sr, 1.2 ≦ i ≦ 2.7,
14.5 ≦ j ≦ 35.5, 0.01 ≦ k ≦ 0.50, 23.9 ≦ n ≦ 57.5)
Phosphors with low luminous efficiency even after baking
The bottom is very few.

[0020]

[Table 1]

[0021] Example 2: by a method analogous to that described in Example _{1, M i MgAl j O n} : Eu k (M is Ba and / or Sr, 1.2 ≦ i ≦ 2.7,14.5 ≦ j ≦ 35.5, 0.
01 ≦ k ≦ 0.50, 23.9 ≦ n ≦ 57.5)
Various phosphors having different i, j, k, and n and phosphors deviating from the composition range of the present invention were prepared, and the baking temperature was changed (held at each temperature for 30 minutes) to obtain the luminance / chromaticity y ratio. The variability was measured. Table 2 shows the compositions of the phosphors, and FIG. 2 shows the fluctuation rate of the luminance / chromaticity y ratio of the phosphor after baking. As can be understood from Table 2 and FIG. 2, the blue phosphor in the composition range of the present invention is less thermally deteriorated even by the baking treatment at 500 to 700 ° C.

[0022]

[Table 2]

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction chart showing the structures of one example of the phosphor of the present invention and a phosphor of a normal composition for comparison.

FIG. 2 is a graph showing a fluctuation rate of a luminance / chromaticity y ratio after baking processing in the phosphor of the present invention and a comparative example.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kanekin Yokota 3330 Nakatsukuma, Kitamoge-cho, Sanyoki-gun, Saga Prefecture Inside Saga Plant of Daiden Co., Ltd. No. Shanghai Yulong Colored Metal Co., Ltd. (72) Inventor Wang Zhenhua No.1 East Dist.Ro, Baoshan District, Shanghai, China Inside Shanghai Yulong Colored Metal Co., Ltd. F-term (reference) in Shanghai Donglong Road No.1 Shanghai Leonglong Colored Metal Co., Ltd. 4H001 CA04 CA07 XA08 XA12 XA13 XA38 XA56 YA63 5C043 AA02 AA03 AA05 CC09 DD28 EB01 EC06 EC20

Claims (1)

[Claims] 1. A composition formula M _i MgAl _j O _n: Eu aluminate (M represented by _k is Ba and / or Sr,
1.2 ≦ i ≦ 2.7, 14.5 ≦ j ≦ 35.5, 0.01 ≦ k ≦ 0.50, 23.9
.Ltoreq.n.ltoreq.57.5), which is a blue phosphor for a three-wavelength fluorescent lamp.