JPS62221466A - Method for forming white diffusion film for tube bulb - Google Patents

Abstract

PURPOSE:To enhance the utilization efficiency of a suspension and to enable uniform and highly efficient painting, in performing electrostatic painting, by atomizing the suspension using a glass container having a specific resistance value. CONSTITUTION:A desired white pigment suspension 9 is prepared to be received in a paint container 1 and this container 1 is placed on an insulating stand 2. In this state, the suspension 9 is pressurized by a pressure feed pump 3 to be sent to a painting gun 4 and injected from a nozzle 8 in a mist form. Voltage of 20-80kV is applied to the nozzle 8 by a high voltage generator 7 and the injected mist like paint is charged with static electricity to be adhered to the inner surface of a glass container 5 on an earthed glass container support stand 6. At this time, by using the glass container 5 of which the resistance value is 12MOMEGA/cm or less, uniform electrostatic painting can be performed efficiently within a short time even if no extremely high voltage is used.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for forming a white diffusion film for a tube, which forms a white diffusion film on the inner surface of a glass container.

2. Description of the Related Art Fluorescent lamps have traditionally been used in large quantities not only in stores and factories but also in ordinary households because of their significantly higher lamp efficiency than light bulbs. However, most fluorescent lamps are ring-shaped or linear, which means they are larger than light bulbs and require ballasts, lighting tubes, etc., making the entire device larger. Their major drawback is that they are more complicated to handle than light bulbs. In recent years, in order to solve these drawbacks and to save power, fluorescent lamps have been molded into a U-shape or double U-shape, and this is integrated with a ballast and lighting tube into a case that includes a glass container. It was set up inside. Many so-called light bulb-shaped fluorescent lamps have been commercialized. In this case, a white pigment is applied to the inner surface of the glass container so that light from a built-in fluorescent lamp is uniformly diffused. The white pigment can be applied using an electrostatic coating method using fine silica powder, which has traditionally been used in light bulbs, or by adding the white pigment used in fluorescent lamps to a binder, such as an aqueous emuldigone resin solution. Wet coating methods using dispersed suspensions are known.

Problems to be Solved by the Invention In a self-ballasted fluorescent lamp, since air is present inside the glass container without exhaust, moisture contained therein adheres to the inner surface of the glass container while the lamp is lit. This is due to the disadvantage that part of the film may fall off in cases where the adhesion strength is extremely weak because there is no binder at all, such as fine silica powder applied to the inner surface of a glass container by electrostatic coating.

On the other hand, in the wet coating method using a suspension using water-based emulsion resin as a binder, the suspension has extremely high foaming properties, making it impossible to apply the coating using a nozzle. After filling the glass container with the suspension, coating is performed by discharging the suspension from the glass container with the opening of the glass container facing downward. The drawback is that it takes a long time to inject and drain, and a large amount of suspension is required per glass container, so an extremely large amount of suspension is required as a whole, and the liquid drops unrecoverably. There was a drawback that the utilization rate of the suspension decreased significantly because the amount of liquid increased.

Means for Solving the Problems The method for forming a white diffusion film for bulbs according to the present invention has an electric resistance of 1.
A glass container with a resistance of 2 MΩ/α or less is placed on a grounded container support, a nozzle to which a high voltage is applied is inserted from the opening of the glass container, and a water-based white pigment suspension i'ff: fog is inserted from the nozzle. It is applied to the inner surface of a glass container by spraying it onto the surface and then dried.

In the so-called electrostatic coating method that utilizes static electricity, the method of applying powder as described above and the method of painting metal etc. using an organic solvent-based paint are well known. In order to solve the problem of film failure due to foaming, which is the biggest problem when coating with an aqueous suspension, the inventors developed an electrostatic coating method in which the suspension is atomized and virtually no bubbles are generated. As a result of various studies on how to apply this method to aqueous suspensions with low resistance values, we first discovered that this can be achieved by using a glass container with a specific resistance value range. Furthermore, it was found that by placing the glass container on a support that is entirely grounded (earthed), electrostatic force can be applied effectively and a uniform coating film can be formed. As a result of experimenting with the resistance value of the glass container,
It is possible if the resistance value is 12MΩ/α or less, especially 8
It has been found that uniform coating is possible without applying an extremely high voltage if it is less than MΩ/cs. When the resistance value of the glass container exceeds 12MΩ/cIR, the applied voltage 11
001cV or more, but in this case, if the nozzle tip and the glass container support are not sufficiently separated, electrical discharge will occur and painting will be impossible.On the other hand, the distance between the nozzle tip and the glass container support must be set so that no discharge occurs. It was found that if the distance was too high, the suspension adhering to the inner surface of the glass container would become non-uniform, which was unsuitable. If the resistance of the glass container is 12 MΩ/mouth or less, no discharge will occur between the nozzle tip and the glass container support as described above, and the electrostatically charged atomized paint will efficiently move through the glass container due to the electrostatic force. It was found that it adheres to the inner surface. As a result of measuring the utilization rate of the suspension, it was found to be 80% or more, which was a significant improvement in the utilization rate compared to 30 to 40 inches in the conventional wet coating method. This is because the amount of suspension used per glass container is sufficient to wet the inner surface of the glass container.

On the other hand, since the suspension adhered to the glass surface in the form of a mist, no air bubbles were generated on the outside of the film, and it was found to be smooth and homogeneous. While the wet coating method required 10 to 15 seconds to coat glass containers, the method of the present invention significantly shortens the time to 0.5 to 1 second, making high-speed mass production possible. It was also recognized that there is a great advantage in being able to become.

Function: According to the structure of the present invention, it is possible to easily obtain a smooth and homogeneous diffusion film that has high adhesion strength to the inner surface of a glass container and has no appearance defects due to bubbles or the like.

Example Next, embodiments of the present invention will be described with reference to the drawings.

Example 1 Calcium phosphate 4000. ! 9 Vinyl acetate and ethylene copolymer emulsicone aoooy deionized water
4000m/l'γ type alumina
200. ! ? After thoroughly mixing and stirring the above materials, pass through a 300 sieve sieve to prepare a white suspension.

Then, as shown in the figure, this is placed into a paint container 1. The paint container 1 is placed on an insulating table 2, and the white pigment suspension 9 is pressurized by the pressure pump 3, passes through the paint gun 4, and is sprayed in the form of a mist from the nozzle 8, which is then pulled up. . The nozzle 8 is supplied with 2o~5ox by the high voltage generator 7.
A voltage of V is applied, and the sprayed atomized paint is charged with static electricity and adheres to the inner surface of a glass container 6 made of soda glass placed on a grounded glass container support 6.

The injection time varies depending on the size of the glass container.
α, for a glass container with a resistance value of 7.6 MΩ/α, it was 0.9 seconds. The amount of adhesion was 1.6 g, and the relative diffuse transmittance was 97%. When the white pigment suspension was applied using the same glass container using the conventional wet coating method, it took 12 seconds to apply and the amount of adhesion was 1. rsji, and the diffuse transmittance was 97chi. As described above, a diffusion film with the same optical properties was obtained in less time than required. Also, glass container 1
In the case of the method of the present invention, the required amount of suspension per individual is eoml, whereas in the conventional method, atsomi and the present invention require less than a bamboo, and the amount of unrecoverable suspension that drops is sufficient for the present invention. In the case of the invention, it was 10 to 1 sm/, whereas in the conventional method, it was 260 m1, and it was recognized that the utilization rate of the present invention was significantly improved.

Example 2 Calcium phosphate 5000 g Aqueous acrylic resin emulsion S soo, ji + Surfactant (Neugen Em 12o manufactured by Dai-Kogyo Seiyaku Co., Ltd.) Aqueous solution (10% concentration) 6 ml After thoroughly mixing and stirring the above materials, 300 g A white pigment suspension is prepared through a mesh sieve. Then, put it into the paint container 1 as shown in the figure.

Thereafter, when coating was performed using a cylindrical glass container with a resistance value of 8 MΩ/lya and a diameter of 9QII in the same manner as in Example 1, the result was 0.
．． It can be applied in 7 seconds and the adhesion amount is 1.2.9. The relative diffuse transmittance was 97 inches. On the other hand, when the same glass container and the same suspension were used for coating using the conventional method, it took 9 seconds to coat and the amount of adhesion was 1. ;J, relative diffuse transmittance was 97 cm. As described above, according to the present invention, a diffusion film with exactly the same optical properties was obtained in less time than required. Also, glass container 1
In the case of the present invention, the required amount of suspension per individual is s o ml, whereas in the conventional method, it is 400 ml, and in the method according to the present invention, the amount of suspension that is dropped and cannot be recovered is 400 ml. The liquid amount was 5 to 10 rnl in the case of the present invention, whereas it was 210 mJ in the conventional method, and it was recognized that the utilization rate was significantly improved in the method according to the present invention.

In the above embodiment, the case where a white diffusion film is formed on the inner surface of a glass container for a self-ballasted fluorescent lamp is described, but the present invention can also be applied to a case where a white diffusion film is formed on a general light bulb, a high pressure discharge lamp, etc. Of course, it can also be applied.

As described in detail, the present invention uses an aqueous white pigment suspension to form a stable, smooth and homogeneous white diffusion film on the inner surface of a glass container. It is possible to provide a method for forming a white diffusion film for a tube, which is suitable for production and has great advantages such as greatly improving the utilization rate of the suspension.

[Brief explanation of drawings]

The figure is a diagram for explaining a method of forming a white pigment diffusion film on the inner surface of a glass container, which is an embodiment of the present invention. 1...Paint container, 2...Insulation stand, 3.
Old...Pressure pump, 4...Painting gun, 5...
...Glass container, 7...High voltage generator, 8.
... Nozzle, 9. Old... White pigment suspension.

Claims (1)

[Claims] A glass container with an electrical resistance of 12 MΩ/cm or less is placed on a grounded container support, a nozzle to which a high voltage is applied is inserted through the opening of the glass container, and a water-based white pigment suspension is poured from the nozzle. A method for forming a white diffusion film for a tube, comprising applying the aqueous white pigment suspension to the inner surface of the glass container by spraying it in the form of a mist and drying it.