JPS61273828A - Formation of phosphor material film - Google Patents

Abstract

PURPOSE:To reduce the scatter of film thickness of a phosphor material by making phosphor emulsion to flow down along the inner face of a glass tube followed by making a shield having a smaller opening area than the opening area of a glass tube lower side opening end to stick fast to said opening end and hot wind to flow into the glass tube. CONSTITUTION:A glass tube 1 to be used for a fluorescent lamp or the like is held upright by a holder 2 while from its upper side opening part the phosphor material emulsion inside a tank 3 is made to jet through a nozzle 4 and flow down along the inner face of the glass tube 1 to be applied on it. Next, a shield 6 having a slit-like opening is made to stick fast to the lower side opening end of the glass tube 1 for allowing hot wind to flow in from an air nozzle 5 arranged on the upper end and emitting it through the slit-like opening for drying. Accordingly, by delaying the flow-down speed of the phosphor material emulsion while partly confining hot wind inside the glass tube 1 in order to reduce the scatter of film thickness of the phosphor material on the upper and lower ends, thus improving quality.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of forming a phosphor coating, and more particularly, to a method of forming a phosphor coating on the inner surface of a glass tube.

Conventional technology Generally, in the manufacturing process of fluorescent lamps, when forming a phosphor coating on the inner surface of a glass tube, the phosphor is dispersed in a suitable solvent together with a binder through the upper opening of the glass tube held upright. After injecting the phosphor suspension and discharging it from the lower opening of the glass tube by gravity, hot air at room temperature to 100°C is blown into the glass tube from the upper opening at a wind speed of 2 to 10 m/sec. By drying the phosphor suspension by blowing with water, a phosphor coating is formed on the inner surface of the glass tube.

Problems to be Solved by the Invention However, according to such a method, the flow of hot air for drying the phosphor suspension is applied to the inner surface of the glass tube from the upper end of the glass tube to the lower end of the phosphor suspension. In order to increase the flow rate, the thickness of the phosphor coating formed at the upper end of the inner surface of the glass tube is thinner than that formed at the lower end, and as a result, the film thickness between the upper and lower ends becomes There was a problem in which large variations in light transmittance occurred in the fluorophore suspension (hereinafter referred to as water suspension) using a water-soluble polymer binder. This is particularly noticeable in the case of body coating formation.

The present invention provides a method for forming a phosphor coating that reduces variations in the thickness of the phosphor coating between the upper and lower ends of the inner surface of a glass tube, thereby making the light transmittance distribution uniform. .

Means for Solving Intermediate Points The method of forming a phosphor coating of the present invention is to cause a phosphor suspension to flow down from an upper opening into a glass tube held upright, thereby irradiating the inner surface of the glass tube with fluorescein. A shielding body having an opening having an opening area smaller than this opening area is closely attached to the lower opening end of the glass tube, and hot air is caused to flow into the glass tube from the upper opening. The phosphor suspension applied to the inner surface of the glass tube is dried by partially discharging it to the outside through the opening of the shield, thereby forming a phosphor coating on the inner surface of the glass tube.

Function: Part of the gas that has flowed into the glass tube is trapped inside the tube.
By slowing down the flow rate of the phosphor suspension from the upper end to the lower end of the inner surface of the glass tube and drying the phosphor suspension at the upper end of the glass tube more quickly, The width of variation in the phosphor coating can be reduced.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 2, a cylindrical glass tube 1 is held upright with a holder 2, and a coating nozzle 4 provided at the lower end of the phosphor suspension storage tank 3 is inserted into the upper opening of the glass tube. Then, the phosphor suspension is spouted out and allowed to flow down into the glass tube 1, and after the phosphor suspension is coated on the inner surface of the glass tube 1, the application nozzle 4 is pulled up. Thereafter, as shown in FIG. 1, hot air (air) at room temperature to 100° C. is flowed in from the air nozzle 5 located above the upper opening of the glass tube 1 at a wind speed of 2 to 1 or IL/sec for 6 minutes. , a shielding body 6 made of metal or the like having a slit-shaped opening 6a at the lower open end of the glass tube 1, as shown in FIG.
are brought into close contact with each other, a portion of the hot air is discharged to the outside through the opening 6a of the shielding member 6, and a portion of the warm air is trapped inside the glass tube 1, whereby the phosphor suspension is discharged from the upper end of the glass tube. Slow down the flow rate to the bottom end. As a result, the phosphor suspension at the upper end of the glass tube 1 can be dried more quickly, and the phosphor coatings at the upper and lower ends of the glass tube 1 can be formed to approximately the same thickness. Can be done. Moreover, it is possible to form a phosphor coating with a smooth film surface over the entire length of the glass tube 1. In addition, in the same manner as above, apply the phosphor suspension to the inner surface of the glass tube, and When the phosphor suspension was dried at a predetermined temperature and wind speed in the same manner as above with a shielding body without an opening in close contact with the open end, the phosphor at the upper and lower ends of the glass tube 1 was dried. The film thickness of the coating varies widely, and the glass tube is filled with hot air that has flowed into it, making it impossible for hot air to flow in from the upper opening, resulting in extremely slow drying of the phosphor suspension, and the film surface. It was confirmed that the problem of grainy texture occurred.

~ ・ As another method, in order to increase the thickness of the phosphor coating on the top end of the glass tube, we conducted an experiment in which we varied the temperature, wind speed, and air volume of the warm air flowing into the glass tube. It was confirmed that the overall thickness of the phosphor coating simply increased or decreased.

Next, examples of the present invention will be described.

Example 1 First, as shown in FIG. 2, a 12 ocIn long glass tube 1 for wattage is held upright with a holder 2.

Next, white phosphor 6002, 325 ml of inbutylene-maleic anhydride 2% aqueous solution, 18 ml of polyethylene glycol nonylphenyl ether, and 2 ml of deionized water.
The aqueous suspension is ejected from a coating nozzle 4 connected to a storage tank 3 containing a water suspension having a composition of 75 ml and flows down into the glass tube 1, and the aqueous suspension is applied to the inner surface of the glass tube 1. . Thereafter, as shown in FIG. 1, hot air (air) of 600 ml was flowed into the glass tube from the upper opening of the glass tube 1 for 5 minutes at a wind speed of 10 rIL/sec using the air nozzle 6 installed above the glass tube. Width 3 at the lower opening end of 1
A shielding body 6 having a fin slit-shaped opening 6a is brought into close contact with the shielding body 6, and a wind speed of 6 m/sec is applied to the inside of the glass tube 1 from the upper opening.
The aqueous suspension was dried by flowing warm air of 'C for 6 minutes to form a phosphor coating on the inner surface of the glass tube 1.

When the weight of the phosphor coating at the upper end (range from the upper end of the glass tube to the lower 10z) of the glass tube 1 thus obtained is 100%, the weight at the center (range of 10 squares in the center) is 100%.
The coating weight ratio of each phosphor coating between the lower end (range from the lower end of the glass tube to 10ffi above) and the upper end was measured, and the results shown in Table 1 were obtained.

On the other hand, using an aqueous suspension having the above composition, applying the aqueous suspension under the same conditions, the speed of drying hot air (air), and the temperature for 1 hour, a shield was placed at the lower open end of the glass tube. In the case of the conventional method in which the glass tube 1 is not provided, the weight ratio of each phosphor coating applied to the lower end, the center, and the upper end of the glass tube 1 was as shown in Table 1.

Table 1 As is clear from Table 1, the method of Example 1 of the present invention improves the coating weight ratio of the phosphor coating between the lower end and the upper end of the glass tube 1 by 21% compared to the conventional method. It can be seen that the width of variation in the film thickness of the phosphor coating between the upper and lower ends can be considerably reduced.

Example 2 First, the 40 watt glass tube 1 was held upright in the same manner as in Example 1. Next, 500 t of white phosphor, 300 ml of nitrocellulose solution, 2 oz of butyl acetate alcohol,
A phosphor suspension having a composition of OWI is applied to the inner surface of the glass tube 1 in the same manner as in Example 1. Then, as shown in FIG. 6 generates warm air at 20℃ (room temperature) at a wind speed of 6 m/s (
While allowing air to flow in for 6 minutes, a shield 6 having the same configuration as above is brought into close contact with the lower opening end of the glass tube 1, and hot air at 20°C is flowed into the glass tube 1 from the upper opening at a speed of 3 m/sec. was allowed to flow in for 6 minutes to dry the phosphor suspension, and a phosphor coating was formed on the inner surface of the glass tube 1.

When the weight ratio of each phosphor coating applied to the center, lower end, and upper end of the glass tube 1 thus obtained was measured, the results shown in Table 2 were obtained.

Table 2 As is clear from Table 2, the method of Example 2 of the present invention improves the coating weight ratio of the phosphor coating between the lower end and the upper end of the glass tube 1 by 18 inches compared to the conventional method. , it can be seen that the width of the variation in the film thickness of the phosphor coating between the upper and lower ends can be made extremely small. was found to be smooth and good.

It has been found through experiments that the opening area of the shield is preferably in the range of 5 to 16 inches with respect to the lower opening area of the glass tube.

Further, the shape of the opening of the shielding body is not limited to the slit shape shown in the above embodiment, but may be circular or stacked with many small holes.
.

As explained above, according to the method of the present invention, a phosphor coating can be formed on the inner surface of a glass tube with less variation in film thickness, and therefore the light transmittance distribution can be made uniform. Moreover, the surface of this phosphor coating can be made smooth.

[Brief explanation of the drawing]

Figure 1 shows a phosphor for carrying out the method of the present invention.
A partially cutaway front view showing an example of a suspension drying device, FIG. 2 is a partially cutaway front view showing an example of a fluorescent suspension coating device, and FIG. It is an enlarged sectional view. 1...Glass tube, 2...Holder, 4.
... Application nozzle, 6 ... Air nozzle,
6...A cover, ea...Opening ◇ Name of agent: Patent attorney Toshi Nakao and 1 other person No. 1
9 Fig. 2 1---fi' ulnar 2--t, rt" Fig. 3

Claims (1)

[Claims] The phosphor suspension is applied to the inner surface of the glass tube by flowing it down from the upper opening into the glass tube held upright, and the phosphor suspension is applied to the lower opening end of the glass tube from this opening area. The coating was applied to the inner surface of the glass tube by closely adhering a shielding body formed with an opening having a small opening area, and causing warm air to flow into the glass tube from the upper opening thereof and partially releasing it to the outside through the opening of the shielding body. A method for forming a phosphor coating, which comprises drying a phosphor suspension to form a phosphor coating on the inner surface of the glass tube.