JPH05159745A - Fluorescent material applying composition for fluorescent lamp - Google Patents

Abstract

PURPOSE:To stabilize aqueous slurry by decreasing its aged deterioration. CONSTITUTION:A complex forming agent is added to a fluorescent material applying composition. The complex forming agent reacts to a metal ion, dissolved in aqueous fluorescent material slurry, to prevent the fluorescent material slurry from deteriorating. Accordingly, since the aqueous fluorescent material slurry is not deteriorated over a long period, a fluorescent lamp of excellent luminous characteristic can be manufactured by using the fluorescent material slurry left alone as it is for a long period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor coating composition applied to a fluorescent lamp, and more particularly to improvement of an aqueous type phosphor coating composition.

[0002]

2. Description of the Related Art Generally, as a method of applying a phosphor to a discharge lamp, there are an organic type using butyl acetate and an aqueous type using water. Recently, workability, economy,
Due to environmental issues, water-based binders using water-soluble binders have become the mainstream.

[0003]

Since the water-based type uses water, it has a problem of poor storage stability as compared with the organic type. In order to prevent spoilage and suppress the growth of bacteria, the pH of the phosphor slurry is adjusted to be alkaline. Further, when the phosphor bulb that has been left for a long time is applied to the glass bulb, the slurry agglomerates and the applied surface is deteriorated, so that it is not practical. Further, the discharge lamp using the phosphor slurry has a problem that both the initial luminous flux and the luminous flux maintenance factor are lower than those of the discharge lamp using the initial phosphor slurry.

This problem can be solved by shortening the usage period of the phosphor slurry. However, it is not possible to use all the phosphor slurries in a short period in the actual manufacturing process of the fluorescent lamp. In particular, the phosphor slurry used for a fluorescent lamp with a small manufacturing quantity cannot exhaust all the phosphor slurry at one time, and the remaining phosphor slurry is stored for a certain period of time and reused. At this time, if the phosphor slurry changes with time and aggregates, a high quality phosphor film cannot be obtained.

The change with time of the phosphor slurry is caused by the metal ions eluted from the phosphor. This can be easily inferred from the fact that the temporal change of the slurry of the phosphor, which is easily soluble in water, is remarkable. If the phosphor itself can be surface-treated so that it has a property of not dissolving in water, it is possible to prevent the slurry from changing over time. However, it is difficult to achieve this without degrading the emission characteristics of the phosphor. Therefore, the water-based phosphor slurry has a drawback that the light emission characteristics are deteriorated due to a change with time.

The present invention has been made in view of the above circumstances, and an object of the present invention is to stabilize an aqueous slurry, thereby using a phosphor slurry which has been used for a long time, and thus exhibits excellent light emission. It is an object of the present invention to provide a phosphor coating composition for a fluorescent lamp, which can produce a fluorescent lamp having characteristics.

[0007]

The phosphor coating composition of the present invention is used for an aqueous phosphor slurry and is characterized by containing a complex-forming agent. The phosphor coating composition comprises a phosphor, a water-soluble binder (binder),
Contains a binder. The phosphor coating composition is in a powder state or a state of being added to an aqueous medium. The phosphor coating composition in powder form is added to water at the time of use to form a phosphor slurry.

The inventors of the present invention conducted extensive studies on the preservability and lamp characteristics of the aqueous type phosphor slurry, and as a result,
It has been found that complexing agents are very effective in stabilizing aqueous slurries.

When the aqueous slurry is stored for a long time, part of the phosphor is eluted. The eluted metal is ionized,
Aggregate the phosphor slurry. In addition, the eluted metal ions cause the chain of the binder to be broken. This problem is solved if metal ions eluted from the phosphor can be retained in a stable form. The present invention adds a complex-forming agent to achieve this. The addition amount of the complex-forming agent is adjusted to preferably 0.001 to 5% by weight, more preferably 0.1 to 0.5% by weight. The added complex-forming agent reacts with the metal ion. The metal ion that has reacted with the complex-forming agent is in a stable complex state. Therefore, the harmful effect of metal ions is prevented, and a stable phosphor slurry is obtained. The complex forming agent has the same effect when the phosphor slurry is prepared or when it is added to the phosphor slurry which has already agglomerated.

As the complexing agent, aminopolycarboxylic acid type ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), trans-1,2-cyclohexadiacin tetrapotacetic acid (CyDTA), glycol ether diacetic acid tetraacetic acid. (GEDTA), diethylenetriaminepentaacetic acid (DTPA) and the like, and ammonium salts thereof can also be used.

[0011]

【Example】

Example 1 A fluorescent lamp is manufactured as follows. Step of obtaining phosphor slurry 29% by weight of blue light emitting phosphor and 32% of green light emitting phosphor
% By weight and 39% by weight of the red light emitting phosphor are mixed.

As a blue light emitting phosphor, europium activated strontium calcium chlorophosphate barium phosphor [(Sr, Ba, Ca) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu],
Cerium, terbium-activated lanthanum orthophosphate phosphor [LaPO ₄ : Ce, Tb] is used as a green-emitting phosphor, and europium-activated yttrium oxide phosphor [(Y, Eu) ₂ O ₃ ] is used as a red-emitting phosphor. ..

To 800 g of the phosphor mixture, 1000 kg of a 0.5% polyethylene oxide (PEO) aqueous solution,
8.9 g of lanthanum acetate (containing lanthanum acetate in an amount corresponding to 0.5% by weight of lanthanum oxide in terms of lanthanum oxide) was mixed, and the suspension was sufficiently stirred while ammonia water was added. To adjust the pH to 9.

Coating and Glass Bulb Processing Step After coating the aqueous slurry on the inner wall of the straight tube bulb of a 40 WSS fluorescent lamp, it is placed in an electric furnace and baked at 550 ° C. for 10 minutes. Upon cooling, a glass bulb having a phosphor layer with a thickness of 15 μ was obtained.

Then, a 40 WSS straight tube fluorescent lamp is manufactured by filling a vacuum exhaust rare gas and mercury by a conventional method. The initial luminous flux of the obtained fluorescent lamp is 3560 lumens, which is 5
The luminous flux maintenance factor after lighting for 00 hours was 97%.

The phosphor slurry prepared in the process of making a prototype of a fluorescent lamp using the phosphor slurry after one month has passed is left at room temperature for one month, and then applied to a glass bulb, and then applied by a conventional method. Four
0WSS straight tube fluorescent lamp is manufactured. The coated surface of the fluorescent lamp manufactured in this manner was agglomerated, and it was not practical as a lamp. By the way, the initial luminous flux was 3420 lumens, and the luminous flux maintenance factor after lighting for 500 hours was 92%.

Step of adding a complex-forming agent to the left-standing phosphor slurry to form a fluorescent lamp In the phosphor slurry left at room temperature for 1 month, 2NH ₄ -EDTA as a complex-forming agent is added to the phosphor. Add 0.1% by weight and stir thoroughly.
A WSS straight tube fluorescent lamp was manufactured.

The fluorescent lamp thus manufactured had a beautiful coating surface equivalent to that when the phosphor slurry was prepared, and had the same initial luminous flux and luminous flux maintenance factor after 500 hours of lighting.

[Example 2] Lead-activated barium disilicate phosphor [BaSi ₂ O ₅ : Pb] 500 g, 0.5% PE
600 g of O aqueous solution, 20% aluminum oxide slurry 2
5g, 10% DTPA-ammonia water 25g was mixed,
Suspend to obtain a phosphor slurry.

Using this phosphor slurry, Example 1
A 40 WSS straight tube fluorescent lamp A was prototyped by performing the same operation as in.

A 40 WSS straight tube fluorescent lamp B was prototyped by using the phosphor slurry left at room temperature for 2 months.

[Example 3] A phosphor slurry is prepared in the same manner as in Example 2 except that the complex-forming agent is not added. After this phosphor slurry was left for 2 months, the one to which DTPA-ammonia water was added was applied to manufacture a 40 WSS straight tube fluorescent lamp C as a prototype.

In addition, D was added to the phosphor slurry left for two months.
A 40 WSS straight tube fluorescent lamp D was prototyped by coating a glass bulb without adding TPA-ammonia water.

40 WSS straight tube fluorescent lamps A, B, C, D
Table 1 shows the initial light emission output and the luminous flux maintenance factor after 500 hours of lighting.

Each fluorescent lamp is manufactured under the following conditions. [Fluorescent lamp A] Add complex forming agent, apply phosphor slurry without leaving it [Fluorescent lamp B] Add complex forming agent, apply phosphor slurry 2
Leave for months to apply [Fluorescent lamp C] First, leave the slurry for 2 months without adding a complex forming agent, and then add with a complex forming agent and apply [Fluorescent lamp D] Fluorescence without adding a complex forming agent Body slurry left for 2 months, then applied

[0026]

[Table 1]

[Example 4] Fluorescence was obtained by mixing 500 g of calcium halophosphate phosphor, 500 g of 0.5% PEO aqueous solution and 4.9 g of yttrium acetate (equivalent to 0.4 wt% of the phosphor in terms of yttrium oxide). Make a body slurry. Using this phosphor slurry, a 40 WSS straight tube fluorescent lamp E was prototyped in the same manner as in practical example 1.

As a compulsory test, this phosphor slurry was allowed to stand at 40 ° C. for 1 month, and the same 40WS was used.
An S straight tube fluorescent lamp F was prototyped.

[0029] m was fabricated a 40WSS capped fluorescent lamps G was further added 0.2 wt% of 2NH _4-EDTA to the phosphor in the phosphor slurry used in the fluorescent lamp F as complexing agent. The characteristics of these fluorescent lamps are shown in Table 2.

[0030]

[Table 2]

[0031]

As shown in these tables, the fluorescent lamp containing the complex-forming agent has no lumps or agglomerates on the film surface and has an excellent maintenance rate. In this way, it is possible to leave the phosphor slurry for a long time to form an excellent fluorescent lamp.
The reason is that the added complex-forming agent stabilizes the aqueous phosphor slurry. It also has the function of restoring the slurry that has changed over time. As described above, the phosphor coating composition of the present invention can be used as a phosphor slurry that has been left for a long period of time, and thus has a large economic effect.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Keiji Ichinomiya 491, Oka, Kaminaka-cho, Anan-shi, Tokushima 100 Nichia Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A phosphor coating composition for a fluorescent lamp, wherein a complex-forming agent is added to the aqueous type phosphor coating composition.