JPS61185837A - Formation of powder film on inner face of tubular bulb - Google Patents

Abstract

PURPOSE:To obtain a phosphor material coating having high adhesion with low powder loss by adhering powder particles onto the inner face of tubular bulb through electrostatic painting then spraying powder adherent thereafter burning to adhere a powder coating. CONSTITUTION:Phosphor material coating 2 is adhered electrostatically onto the inner face of a glass tubular bulb 1. Then it is transferred to spraying process of adherent for increasing the adhering force of said coating 2 where said tubular bulb 1 is inserted with a solution spray nozzle 8 while cooling and rotating to spray small amount of adherent solution onto said coating 2 and permeate through said coating 2 into the inner face of said tubular bulb 1. Thereafter, said tubular bulb 1 is burnt to evaporate only the solution in adherent solution on said coating 2 and the inner face of said tubular bulb 1 while to dissolve the adherent thus to adhere said coating 2 forcibly onto the inner face of said tubular bulb 1 and to complete adherent forming process of the phosphor material coating 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement in a method for forming a powder coating such as a phosphor on the inner surface of a glass bulb by using an electrostatic coating method. be.

[Conventional technology]

Conventionally, for example, the inner surface of the glass bulb (11) of a high-pressure mercury lamp as shown in Fig.
), first, a phosphor powder, an organic or aqueous lacquer, and an appropriate amount of adhesive are mixed and stirred to form a coating liquid. Then, this coating liquid is sprayed onto the inner surface of the tube glass bulb from a nozzle, etc., and then dried, and further heated in a baking oven at 500 to 700°C for 4 to 40 minutes.
Bake for 7 minutes to remove the lacquer components.

Thereafter, the light coating that had adhered to the neck portion (3) of the tube glass bulb fil was wiped off using a two-turn brush or the like. Furthermore, the phosphor removed at this time is usually recovered and reused.

[Problem that the invention seeks to solve]

However, in the above coating method, the adhesion of the light coating (2) is strong and the subsequent steps of sealing the outer tube and exhausting the outer tube are required.

The cap technique has the advantage of preventing the light coating (2) from peeling off during the process and handling after completion of the lamp, but on the other hand, it requires an organic or water-based lacquer to obtain the desired coating. In addition, it is difficult to recover the coating liquid during application and drying of the phosphor coating liquid, which not only has the disadvantage of a large loss of phosphor use, but also the drying of the coating film. A large amount of thermal energy is required to completely remove the lacquer components by heating and baking, and if even a small amount of lacquer components remain in the phosphor coating (2), the lacquer components will remain in the phosphor coating (2) during the life of the lamp. This has the disadvantage that the light coating (2) becomes black and the luminous efficiency decreases.

As a method for eliminating the drawbacks of the conventional method of forming a phosphor film using a coating liquid, as shown in FIG. A powder injection device (7) connected to the other end of the static electricity generation power source (4) on the inner surface of the glass bulb fil.
The spray nozzle (61 sprays the coating powder,
Various powder electrostatic coating methods have been proposed and are in practice in some cases, in which charged phosphor particles are electrostatically deposited to form a phosphor coating (2).

This method forms the phosphor film (2) without using lacquer or coating liquid, so there is no need for a drying process after applying the coating liquid, so there is less loss of phosphor material, and there is no need for a heating and baking process. Moreover, it has the advantage that there is almost no chance that the light coating (2) will darken during the life of the lamp and that the luminous efficiency will be reduced.

However, since this method attempts to form a phosphor film (2+ fe) by electrostatic force, it is necessary to use phosphor particles whose particle size has been pulverized to about 3 microns, which is the same as in the conventional method. However, it has the drawback that the initial luminous efficiency of the phosphor decreases, and the adhesion force is significantly weaker than that of conventional methods. There is a drawback that the phosphor coating (2) often comes off and falls off due to shock during handling.

This invention was made in view of the above-mentioned circumstances, and the purpose is to reduce powder usage loss, provide a powder coating with strong adhesion, and not require a large amount of thermal energy to form the coating. The object of the present invention is to provide a method for forming a powder coating in which the luminous efficiency of the luminous material is less reduced during the initial period and during the life of the lamp.

[Means for solving problems]

The method for forming a powder film according to the present invention involves adhering powder particles to the inner surface of a tube using an electrostatic coating method, and then spraying a powder adhesive solution onto the inner surface of the tube.

Thereafter, the tube was heated and fired to form a powder coating.

[Effect]

In this invention, as used in the conventional coating method,
The phosphor powder, which has a relatively large particle size, is directly attached to the inner surface of the glass bulb by electrostatic force using an electrostatic coating method without using a coating liquid, and after cooling, an appropriate amount of adhesive solution is applied to it. After spraying, the tube glass bulb is heated and baked to completely remove only the solution of the adherend solution that has penetrated through the spray, and the adherend is melted in the same way as in the coating method to form a phosphor coating. Because it forms an adherent film, there is less loss of use of the phosphor, and the tearing force is as strong as that of the liquid coating method.However, unlike the liquid coating method, a large amount of thermal energy is required to form a phosphor coating. It is possible to form a powder coating that is not necessary and that reduces the reduction in the luminous efficiency of the luminous body during the initial stage and during the life of the lamp.

〔Example〕

An embodiment of the present invention will be described in detail below in the order of its steps with reference to FIGS. 2 and 1.

Note that the same or equivalent parts as in FIGS. 2 and 3 are designated by the same reference numerals. Another embodiment is for forming a light coating on the inner surface of a glass bulb of a fluorescent high-pressure mercury lamp. First, a phosphor coating (2) is electrostatically attached to the inner surface of a glass bulb (1) using a construction method similar to that of the conventional method as shown in FIG. In other words, a gas burner (
5) While rotating the outer glass bulb (1) connected via the flame around its axis, the burner (
5) to raise the temperature to about 150°C to 200°C, and then connect the powder injection nozzle (6) connected to the negative electrode at the other end of the static electricity generating power source (41) to the tube glass bulb fil.
The static electricity generation power source (4) is activated to apply a voltage of approximately 40 to 80 mm, and a luminous object with a diameter of approximately 6 to 10 microns is ejected from the injection nozzle (6). Pressurize and eject with dry air or nitrogen, etc. At this time, the electrical resistance of the tube glass bulb (1) has decreased considerably due to heating.

The burner (5) passes through the flame to the tube glass bulb fi+
An electric path is formed to the inner surface of the tube glass bulb (1), and the inner surface of the tube glass bulb (1) is positively charged, and the injection nozzle (6)
The fluorescent material ejected from the tube is negatively charged, and the charged fluorescent material is attracted to the glass bulb (11) and adheres to the inner surface of the glass bulb (1), where it loses its charge. Since an electric circuit is formed on the inner surface of the glass bulb (1), the inner surface of the glass bulb (1) continues to be positively charged and attracts the light object, causing it to adhere to the inner surface of the glass bulb (1). The phosphor coating (2) is applied electrostatically.

Next, a glass bulb (1) with a light coating (2) electrostatically attached to its inner surface in this manner is prepared.

As shown in FIG. 1, the step of spraying an adhesive solution to significantly enhance the adhesion of the phosphor coating (2) is carried out, and the tube glass bulb (1) is heated approximately with an air blower (not shown) or the like. While cooling to below 60℃.

The solution spray nozzle (8) connected to the solution sprayer (9) is inserted into the tube glass bulb (1) while rotating about its axis, and the solution spray nozzle (8) is then sprayed with, for example, boric acid or hexametaphosphoric acid. An adhesive solution such as an aqueous solution of a substance with a low melting point such as soda is applied to the phosphor coating (2).
Spray a small amount onto the surface of the phosphor coating (2) and let it soak into the inner surface of the glass bulb fi+.

After that, the tube glass bulb (1) is heated and baked with a burner or the like (not shown) to form a light coating (2).
Only the solution of the adhesive solution on the inner surface of the glass bulb (1) is evaporated and removed, and the adhesive is melted to coat the phosphor coating (2) on the glass bulb (1).
By strongly adhering the phosphor coating to the inner surface of the phosphor coating [2], the process of forming the phosphor coating [2] is completed.

Next, the present invention was applied to a means for depositing a phosphor coating on the inner surface of 20 glass bulbs for a general 400 watt high pressure mercury lamp having a maximum outer diameter of about 11 s (O). A description will be given of a specific process procedure shown in one example.

First, as shown in Fig. 3, the tube knob was connected to the positive electrode of the static electricity generating power source via a gas burner flame, and heated uniformly to about 150°C to 200°C while rotating around its axis. ℃, and then a powder injection nozzle connected to the negative electrode of the static electricity generation power source is inserted into the pulp tube while the static electricity generation power source is operated to apply a voltage of about 50 KV and the powder is discharged from the injection nozzle. Approximately 0.8 (
It was pumped with nitrogen at a pressure of kg/Cr, and was ejected to form a luminous coating on the inner surface of the tube pulp using electrostatic force, which caused it to adhere to the neck of the tube pulp. At the same time as removing the light body, about 40% of the tube pulp
After cooling to ℃, while rotating this tube pulp around its axis and inserting a solution spray nozzle into the tube pulp, an aqueous solution of sodium hexametaphosphate was applied using an ultrasonic humidifier. and spray about 0.3 (g),
After leaving it for about 4 minutes, the tube pulp was heated and fired from the outside at about 40° C. with a gas burner to form a phosphor coating on the inner surface of the tube pulp, and then the sealing process was carried out in the same manner as in the conventional method. When the lamp was completed using the above lamp manufacturing process, the phosphor coating did not peel off or fall off like in conventional electrostatic coating.
As a result of testing the adhesion of phosphor coatings by bombarding each other with 00 Watt high-pressure mercury lamps, the adhesion strength was significantly stronger than that of conventional electrostatic coating methods, and that of liquid coating methods. It was confirmed that they were equivalent, and as a result of measuring the luminous flux maintenance rate by lighting this lamp at the rated voltage for SOO time, the initial luminous flux exceeded that of the conventional electrostatic coating method, and the luminous flux maintenance rate was equivalent. The above was confirmed, and the effects of the present invention were fully confirmed.

In the above example, a description was given of what was carried out to form a phosphor wave and a film on the inner surface of the bulb pulp of a general high-pressure mercury lamp of 400 watts.
Not only for other types of tube pulp, but also for metal halide lamps, high-pressure sodium lamps, etc., where a luminous coating is applied to the inner surface of the tube pulp, and tube glass bulbs for metal halide lamps, high-pressure sodium lamps, incandescent lamps, etc. It goes without saying that the same procedure can be carried out in the case where a diffusion coating such as a silica coating is formed on the inner surface, and the same effect can be obtained.

In addition, in the above example, sodium hexametaphosphate was used as the adhesive, the solution was sprayed with an ultrasonic humidifier, and the mixture was heated and baked with a burner at about 400°C. The method of spraying the solution and the temperature method of firing are not limited to these, and the adhesive may be, for example, boric acid or low-melting glass, and the firing may be performed during the sealing or evacuation process. [Effects of the Invention] As described in detail above, the present invention provides coating powder that is sprayed onto the inner surface of a tube glass bulb connected to one end of the static electricity generating power source from an injection nozzle connected to the other end of the static electricity generating power source. After spraying particles and electrostatically adhering the charged powder particles to the inner surface of the tube, spraying an adhesive solution of the powder onto the inner surface of the tube, and then heating and baking the tube. Since the powder coating is formed by applying a powder coating, it does not require a large amount of thermal energy to form a powder coating, unlike conventional methods, there is little loss of powder usage, and the powder coating has a strong adhesion force. ,
Moreover, in the case of a phosphor coating, a powder coating can be provided in which the luminous efficiency decreases little during the initial period and during the life of the lamp, and its practical effects are extremely significant.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of the present invention. Fig. 2 is a schematic explanatory view showing a method of depositing and forming a light coating on the inner surface of a glass bulb of a conventional fluorescent high-pressure mercury lamp, and Fig. FIG. 3 is a schematic explanatory diagram showing a method of depositing and forming a photon coating. Note that the same reference numerals in each figure indicate the same or corresponding parts. m is an outer glass tube, (2) is a powder coating, (4) is a static electricity generation power source, (5) is a burner, and (6) is a powder injection nozzle. (8) is a solution spray nozzle, and (9) is a solution sprayer.

Claims (1)

[Claims] Coating powder particles are injected from a spray nozzle connected to the other end of the static electricity generating power source onto the inner surface of a tube glass bulb connected to one end of the static electricity generating power source, and the charged powder particles are electrostatically After adhering to the inner surface of the glass bulb,
Formation of a powder coating on the inner surface of the tube, characterized in that the adhesive solution of the powder is sprayed onto the inner surface of the glass bulb, and then the glass bulb is heated and baked to form a powder coating. Method.