JP2827529B2 - Aqueous coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous coating composition for preparing a phosphor coating solution by dissolving or suspending it in pure water in a process of forming a fluorescent film of a discharge lamp.

[0002]

2. Description of the Related Art Generally, in the step of forming a fluorescent film of a discharge lamp, phosphor particles are suspended in a binder solution, and a suitable surfactant and an antifoaming agent are added to the suspension to add a binder. Time must be mixed. In particular, in the case of an aqueous binder different from an organic solvent, it takes several hours to prepare an aqueous solution of polyethylene oxide.

[0003] By the way, except for the preparation of a binder and the preparation of a binder slurry, which require a great deal of time to prepare a phosphor coating solution, if the phosphor coating solution can be mixed in advance with the phosphor, Preparation is instantaneous and extremely convenient.

[0004]

However, as disclosed in JP-A-63-289087, the surface of the phosphor particles is coated with a binder of phosphate, borate, aluminum oxide or a mixture thereof. Or mixing other binders and phosphors, but mixing the binders and binders with the phosphors, due to the dispersibility of the phosphor coating solution, since particles are adhered by the binder can not be simplified discharge lamp phosphor coating coating solution preparation step becomes a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an aqueous coating mixture composition which can immediately prepare a phosphor coating solution simply by dissolving it in pure water in a process for preparing a phosphor coating solution for a discharge lamp.

[0006]

Means for Solving the Problems As shown in Japanese Patent Application No. 2-26677 previously filed by the present inventors, the present inventors have disclosed:
Rare earth compounds such as lanthanum and yttrium as binders for discharge lamps have been found to be extremely excellent in terms of initial luminance and maintenance of luminous flux. As a result,
The present invention has been completed.

[0007] That is, an object of the present invention is to provide a water-based coating characterized in that a fine-powder aqueous binder component, a fine-powder binder component composed of a rare earth compound, and phosphor particles are uniformly mixed. The problem is solved by a mixed composition for use.

[0008] Preferably, the fine powdery aqueous binder component is mainly composed of polyethylene oxide particles.

Further, the rare earth compound is La, Y, Gd,
It is composed of fine particles of a water-soluble salt of a rare earth element selected from the group consisting of Dy, Sc, Sm, Eu, Ho, Tm and Lu. This is because, after baking at the time of manufacturing the discharge lamp, it is desirable that the absorption of radiation in the region from ultraviolet light to visible light be small.

[0010]

The fine powdery aqueous binder component, the fine powdery binder component composed of a rare earth compound, and the phosphor particles are uniformly mixed, so that the aqueous coating mixture composition of the present invention is pure water. The phosphor coating solution can be prepared by merely dissolving and suspending the phosphor solution, that is, in a processing time of only ten and several minutes in the phosphor coating solution preparation step in the discharge lamp. As in the prior art, by preparing a phosphor coating solution from starting materials in which a binder component, a binder component, and phosphor particles are separately provided, a processing time of about ten hours was required. Dissolving and suspending the coating mixture composition in pure water requires only about ten minutes.

That is, conventionally, in order to prepare an aqueous binder such as polyethylene oxide, a stirring time of 4 to 8 hours was required, and further, a binder slurry was required in a period of 50 to 100 hours. The aqueous coating mixture composition of the present invention does not require such a large amount of time, and may be simply dissolved and suspended in pure water and stirred for only about ten minutes.

[0012]

Embodiments of the present invention will be described below in detail.

Example 1 A mixed composition for aqueous coating was prepared as follows.

First, halophosphate phosphoric acid phosphor particles
1.2 kg and 15 g of finely powdered lanthanum nitrate [La (NO ₃ ) ₃ .5.6H ₂ O manufactured by Nippon Yttrium) are sufficiently mixed, and then 5 g of finely powdered polyethylene oxide is sufficiently mixed with this mixture. Thus, a mixed composition for aqueous coating was obtained.

Next, a method for preparing a phosphor coating liquid of the aqueous coating mixture composition thus prepared will be described.

The above-mentioned aqueous coating mixture composition is dissolved in 995 g of pure water, and the pH is adjusted to 9 with ammonia water while stirring.
Increased to 1. The stir time was about 8 minutes. Thereafter, stirring is continued for 5 minutes, and the mixture is left for 3 minutes to obtain a phosphor coating solution. In this case, at the time of stirring, a suitable surfactant and antifoaming agent may be appropriately added.

A 40 WSS straight tube was manufactured using the phosphor coating solution thus obtained, and the phosphor, the binder, and the binder were stirred from the same phosphor, binder, and binder as the aqueous coating mixture composition of this embodiment. Thus, a clean fluorescent film similar to the conventional one was obtained, and the film strength was equivalent to the conventional one. When the fluorescent lamp was turned on, the emission color, emission luminance, and luminous flux maintenance were the same as those in the related art.

Example 2 A divalent europium- activated strontium / barium halophosphate phosphor as a blue light-emitting component, cerium and terbium-activated lanthanum orthophosphate phosphor as a green light-emitting component, and trivalent europium as a red light-emitting component 620 g of a three-wavelength phosphor mixed with an activated yttrium oxide phosphor, 7.8 g of lanthanum nitrate in the form of fine powder similar to that in Example 1, and polyethylene oxide 3 in the form of powder similar to that of Example 1 A mixed composition for aqueous coating consisting of 0.5 g was prepared and dissolved in 496.5 g of pure water in the same manner as in Example 1 to obtain a phosphor coating solution.

A three-wavelength fluorescent lamp of 40 WSS was prepared from the obtained phosphor coating solution. As in Example 1, the finish of the coated surface and the film strength were lower than those obtained by stirring for 15 hours. The same was true for the emission color, color rendering, emission luminance, and luminous flux maintenance of the fluorescent lamp.

[0020]

As described above, according to the present invention,
A fine powdered aqueous binder component, a fine powdered binder component composed of a rare earth compound, and an aqueous coating mixture composition in which phosphor particles are uniformly mixed are used in a phosphor coating solution preparation step of a discharge lamp. It is possible to provide an aqueous coating mixture composition that can immediately prepare a phosphor coating solution simply by dissolving it in pure water.

────────────────────────────────────────────────── ─── of the front page continued (72) inventor Osamu Sakai Anan City, Tokushima Prefecture kaminaka Oka 491 address 100 Nichia chemical industry Co., Ltd. in the (58) investigated the field (Int.Cl. ^6, DB name) C09K 11 / 02 H01J 9/22

Claims (3)

(57) [Claims] 1. An aqueous coating composition which is dissolved and suspended in water to form a phosphor coating solution, comprising: a fine powder aqueous binder component; a fine powder binder component comprising a rare earth compound; and a phosphor. A mixed composition for aqueous coating characterized by being uniformly mixed. 2. The mixed composition for aqueous application according to claim 1, wherein the fine powdery aqueous binder component is mainly composed of polyethylene oxide particles. 3. The method according to claim 1, wherein the rare earth compound is La, Y, Gd,
The aqueous coating composition according to claim 1, comprising fine particles of a water-soluble salt of a rare earth element selected from the group consisting of Dy, Sc, Sm, Eu, Ho, Tm, and Lu. Mixed composition.