JPS61195999A - Formation of coat of fluorescent substance - Google Patents

Abstract

PURPOSE:To form a uniform coat of fluorescent substance by immersing a substrate wherein a solidified layer of water glass is formed on the surface of an electrode into a suspension of the fluorescent substance and settling the particles of the fluorescent substance on the solidified layer of water glass. CONSTITUTION:A solidified layer 6 of water glass is formed on the surface of a substrate 2 wherein an electrode 5 of a graphite series material is formed on the surface thereof. This substrate 2 is immersed into an electrolyte 4 suspended with the particles 3 of fluorescent substance and the particles 3 in the electrolyte 4 are settled on the solidified layer 6 of water glass which is hydrolyzed to elute alkali metal and electrified and thereby the coat of fluorescent substance is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for forming a phosphor coating film that can form a uniform phosphor coating film on a substrate.

[Conventional technology]

A precipitation method has been known as a general method for forming a phosphor coating on a substrate. This sedimentation method is the second
As shown in the figure, a substrate 2 is placed in a coating bath 1, and a barium salt solution such as barium acetate or barium nitrate is injected into the coating bath 1. A powder phosphor (for example, a metal such as ZnS) is poured into a water glass solution from above. (containing sulfides) is evenly distributed and allowed to stand still. Then, the phosphor particles 3 settle on the substrate 2 in the electrolytic solution 4 containing the barium salt solution and the suspension, forming a deposited layer of the phosphor particles 3. In this state, the electrolyte 4 is gently drained from the coating tank 1 using a drain plug (not shown), and the substrate 2 is taken out from the coating tank 1, the deposited layer of phosphor particles 3 is dried, and the phosphor coating film is formed. It is formed on the substrate 2.

As shown in FIG. 3, the same method is adopted when an electrode 5 made of a graphite material is formed on the surface of the substrate 2 and a coating film of phosphor particles 3 is formed on the electrode 5. It will be done.

[Problem that the invention seeks to solve]

When forming a phosphor coating film by the above precipitation method, the metal sulfide phosphor particles 3 adsorb positive ions in the electrolytic solution 4 and are positively charged. On the other hand, the electrode 5 made of graphite material is not polarized even in the electrolyte 4, so the electrode 5 and the phosphor particles 3 that have settled thereon are only in physical contact and there is no attraction between them. Therefore, the deposited layer of phosphor particles 3 is very easy to collapse.
The deposited layer of the phosphor particles 3, which is uniform when it has settled, often becomes non-uniform as later steps progress.For example, when the electrolyte 4 is applied and removed from the el, the deposited layer is drawn by the water flow. The phosphor particles 3 inside may leak out. Furthermore, even after the electrolyte 4 is removed, the phosphor particles 3
If the deposited layer is in a wet state before being dried, the deposited layer will peel off due to a slight impact, and this tends to occur during the transition to the drying process. As a result, the thickness of the phosphor coating layer formed is often non-uniform, and obtaining a uniform phosphor coating layer requires skill and is a difficult task.

The present invention is an improvement on the conventional method for forming a phosphor coating film using the sedimentation method in order to eliminate the above-mentioned disadvantages. The aim is to obtain a membrane through simple operations.

[Means for solving problems]

The method for forming a phosphor coating film of the present invention for solving the above problems will be described below. Note that the symbols are attached to Fig. 1 (an enlarged cross-sectional view of a phosphor coating film obtained by applying the present invention) and Fig. 2 (a diagram explaining the formation of a phosphor coating film by the sedimentation method). .

In the method of forming a phosphor coating film of the present invention, a substrate 2 on which an electrode 5 made of a graphite material is formed is immersed in a phosphor suspension 4 of metal sulfide. In the method of forming a phosphor coating film by depositing phosphor particles 3 on an electrode 5 of a substrate 2, a solidified layer 6 of water glass is formed on the surface of the electrode 5.
The substrate 2 on which is formed is immersed in a phosphor suspension 4, and the phosphor suspension 4 hydrolyzes the alkali metal to elute and suspend it on the charged water glass solidified layer 6. A method is adopted in which the phosphor particles 3 in the suspension are allowed to settle to form a phosphor coating.

[Function] - The metal sulfide phosphor particles 3 adsorb positive ions in the electrolytic solution 4 and are positively charged. On the other hand, the solidified layer 6 of water glass formed on the surface of the electrode 5 of the substrate 2 is hydrolyzed in the phosphor suspension 4 to elute an alkali metal and is negatively charged. Therefore, the positive charges of the phosphor particles 3 that have settled and the negative charges of the solidified layer 6 of water glass attract each other, and the phosphor particles 3 are stably deposited on the substrate 2.

〔Example〕

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

For example, a commercially available water glass (28% by weight solution of sodium silicate) in which the electrode 5 is formed by printing graphite on a substrate 2 made of glass by a known method and sintering it. The substrate 2 on which the electrodes 5 are formed is immersed for about 30 minutes in a solution in which 1 volume is dissolved in 1 volume of pure water.

After taking it out, it is dried at room temperature for about 30 minutes, and then maintained at Bθ~1006C in a dryer and gently heated to dry.

Then, a film of solidified layer 6 of water glass is formed. At this time, care must be taken because if rapid heating and drying is performed, the water will evaporate only from the surface of the water glass, increasing its viscosity, preventing the internal water from diffusing, and causing numerous cracks in the film.

The solidified layer 6 of water glass is formed.

It has a strong and dense network structure with bonds and does not dissolve easily.

The electrode 5 covered with the solidified layer 6 of water glass in this way
A phosphor coating film is formed on the substrate 2 on which the phosphor coating has been formed, in the same manner as the conventional phosphor coating film formation method using the sedimentation method. In other words, as shown in FIG. , and a barium salt solution is injected into it.A suspension of powdered metal sulfide phosphor suspended in a water glass solution is uniformly sprinkled over the solution, and the solution is left to stand still. Then, the phosphor particles 3 settle on the substrate 2 in the electrolytic solution 4 in which the barium solution and the suspension are mixed, and a deposited layer of the phosphor particles 3 is formed.

At this time, the surface of the solidified water glass layer 6 is hydrolyzed by the electrolytic solution 4. That is, Ha'' ions are eluted into the solution 4 by the reaction shown in the following equation, and the surface of the solidified layer 6 of water glass has negative polarity.

Na2O・n5102 + H2O; second NaOH+
nsl 02 Positively charged phosphor particles 3 are deposited there.

In other words, the phosphor particles 3 and the water glass solidified layer 6 are electrically attracted to each other.

In this state, the electrolyte 4 is removed from the coating tank l, and the phosphor particles 3 are
The deposited layer is dried to form a phosphor coating.

In the above embodiment, the solid layer 6 of water glass was immersed in a sodium silicate solution as a water glass solution to form the solid layer 6 on the electrode 5 of the substrate 2, but a potassium silicate solution may also be used. Alternatively, a water glass solution may be applied by spraying.

〔Effect of the invention〕

As explained above, according to the phosphor coating film forming method of the present invention, the phosphor particles that have settled and the solidified layer of water glass are electrically attracted to each other, so that the phosphor particles are stably attached to the substrate. Deposit. Therefore, the phosphor particles do not collapse during the process, and the phosphor coating film formed is uniform.

[Brief explanation of drawings]

FIG. 1 is an enlarged view of a phosphor coating film formed by the method of the present invention, FIG. 2 is a diagram illustrating the formation of a phosphor coating film by a precipitation method, and FIG. 3 is an enlarged view of a phosphor coating film formed by a conventional method. An enlarged view of the phosphor coating film.

Claims (1)

[Claims] A substrate on which an electrode made of a graphite material is formed is immersed in a phosphor suspension of metal sulfide, and the phosphor particles in the suspension are precipitated onto the electrode, forming a phosphor coating film. In this method, a substrate on which a solidified layer of water glass is formed on the surface of the electrode is immersed in a phosphor suspension, and the alkali metal is eluted by being hydrolyzed by the phosphor suspension. A method for forming a phosphor coating film, characterized in that phosphor particles in a suspension are precipitated on the charged solidified layer of water glass.