JPH01204331A - Manufacture of fluorescent lamp - Google Patents

Abstract

PURPOSE:To prevent the crack or the exfoliation of the metallic oxide film of a lamp during the cooling time by coating a suspension of metallic oxide powder on the inner surface of a tubular glass bulb and then by heating the glass bulb at a temperature higher than the combustion temperature of the solvent so as to make the film after heating the said bulb at a temperature lower than the combustion temperature of the solvent. CONSTITUTION:A suspension of a metallic oxide powder in a solvent is coated on the inner surface of a tubular glass bulb 1 and dried. The glass bulb 1 coated with, for example, titanium oxide suspension is heated at a temperature lower than the combustion temperature of the solvent to produce the film of titanium oxide. Then a suspension of a phosphor powder in nitrocellulose and butyl acetate is coated on the titanium oxide film, dried, and heated up for combustion. Thereby the solvent nitrocellulose in the phosphor film and the titanium oxide film is burned, so that the phosphor film 3 is produced on the metallic oxide film 2 such as titanium oxide and therefore the exfoliation of the metallic oxide film from the inner surface of the glass bulb can be prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a fluorescent lamp in which a metal oxide film is coated on the inner surface of a tube-shaped glass bulb, and a phosphor film is coated on top of the metal oxide film. This invention relates to improvements in manufacturing methods.

(Prior art) For example, anti-fading fluorescent lamps and rapid-start anti-fading fluorescent lamps with internal conductive coatings are made by coating the inner surface of a tube-shaped glass bulb or with a thin film of tin oxide and antimono oxide. A metal oxide film such as a thin film of titanium oxide is deposited, and a phosphor film is deposited on top of the metal oxide film. The conventional method of depositing a film of the metal oxide on the inner surface of the glass bulb of these fluorescent lamps is, for example, in the case of fluorescent lamps for preventing fading, (1) nitrified cotton is dissolved in butyl acetate in a solvent; A suspension of titanium oxide TiO2 powder is applied to the inner surface of a glass bulb to form a titanium oxide coating, and then dried. (2) Heat the above glass bulb with titanium oxide coating on the inner surface to 550°C to 60°C.
Firing at a temperature of 0°C burns the nitrified cotton and forms a titanium oxide film. (3) On the titanium oxide coating of a glass bulb whose inner surface titanium oxide coating was fired and nitrified cotton was burned, phosphor powder was suspended in a solvent in which nitrified cotton was dissolved in butyl acetate. (4) Fluorescence The glass bulb with the body coating film adhered to the inner surface is fired at a temperature of 550°C to 600°C to burn off the nitrified cotton and form a phosphor film. It has been common practice to form a metal oxide film on the inner surface of a glass bulb and a phosphor film thereon through the above four steps. Of the above four steps, (2
After firing the glass bulb at 550° C. to 600° C. in step (3), the glass bulb is cooled to room temperature before proceeding to step (3). At this time, a problem occurred in which the titanium oxide coating on the inner surface of the glass bulb peeled off from the inner surface of the glass bulb. This problem is caused by heating the glass bulb to 550℃.
It is thought that when heated to 600°C to 600°C, the titanium oxide film cracks and peels off due to the difference in thermal expansion between the glass constituting the glass bulb and the titanium oxide film. The above phenomenon may occur not only in titanium oxide films but also in other metal oxide films. The attached figure is a cross-sectional view of a glass bulb as an example of a fluorescent lamp for preventing color fading, and the inner surface of the glass bulb (1) is coated with a coating (2) of a metal oxide such as titanium oxide. Oxide film (2
) is coated with a phosphor coating (3). A problem arises in that the metal oxide film (2) is coated on the inner surface of the glass bulb (1) and the metal oxide film peels off during cooling after the heating and firing process at a temperature of 550°C to 600°C. .

(Problems to be Solved by the Invention) In the conventional method for manufacturing fluorescent lamps, it is difficult to heat and bake a metal oxide film such as titanium oxide deposited on the inner surface of a tubular glass bulb at a temperature of 550°C to 600°C. There was a problem that the metal oxide coating would peel off from the inner surface of the glass bulb during subsequent cooling.

The method for manufacturing a fluorescent lamp of the present invention has been developed in response to the above-mentioned problems, and an object of the present invention is to provide an improved method for manufacturing a fluorescent lamp that does not cause peeling of the metal oxide film from the inner surface of the glass bulb.

[Structure of the invention]

(Means for Solving the Problems) A method for manufacturing a fluorescent lamp of the present invention is to apply a suspension of metal oxide powder in a solvent to the inner surface of a tubular glass bulb to form a metal oxide coating film. and then heating the glass bulb at a temperature lower than the combustion temperature of the solvent, and after the above step heating the glass bulb at a temperature higher than the combustion temperature of the solvent to form a metal oxide coating and a phosphor coating. and a step of forming a film by burning the solvent.

(Function) The method for manufacturing the fluorescent lamp of the present invention includes (1) suspending metal oxide powder, such as titanium oxide powder, in a solvent consisting of nitrified cotton and butyl acetate, on the inner surface of a tubular glass bulb; Apply the suspension and let it dry. (2) The above-mentioned glass bulb with a titanium oxide coating film adhered to the inner surface is heated at a temperature at which the solvent of the coating film such as titanium oxide does not burn, for example, 300°C to 500°C in the case of nitrified cotton to oxidize the above-mentioned glass bulb. Forms a coating of titanium, etc. Due to the formation of the coating film at the above temperature, the nitrified cotton in the solvent is not completely burned and vaporized and remains in the coating film, so even if the glass bulb is cooled to room temperature after step (2), the above coating No peeling of the film occurs. In the next step (3), a phosphor suspension made by suspending phosphor powder in a solvent of nitrified cotton and butyl acetate is applied to a titanium oxide coating that is applied to the inner surface of the glass bulb in step (2). Apply on top and let dry. (4) A glass bulb whose inner surface is coated with a phosphor coating on a metal oxide coating such as titanium oxide is fired at a temperature of 550° C. to 600° C., which is the same as in the conventional method.

By the above-mentioned firing, the nitrified cotton of the solvent in the phosphor coating and the titanium oxide coating is burned, and a glass bulb is formed in which the phosphor coating is deposited on the metal oxide coating such as titanium oxide.

(Example) Details of the method for manufacturing the fluorescent lamp of the present invention will be explained with reference to Examples. The present inventors implemented the manufacturing method of the present invention, for example, in manufacturing an anti-fading fluorescent lamp 40W-FL40S-N-8DL-NU. That is, the outer diameter is 32.
A suspension of titanium oxide powder suspended in a solvent of nitrified cotton and butyl acetate was applied to the inner surface of a 5 mm tubular glass bulb and dried. Next, the glass bulb is heated at a temperature lower than the temperature at which the nitrified cotton as the solvent burns, that is, 300°C to 5000G.

For example, a coating film of titanium oxide was formed by heating at a temperature of 450°C. After this step, the titanium oxide coating did not peel off at all when the glass bulb was cooled to room temperature. A phosphor suspension made by suspending phosphor powder in a solvent of nitrified cotton and butyl acetate is applied onto the titanium oxide coating film of the glass bulb whose inner surface is coated with the titanium oxide coating film, and then dried. , a temperature higher than the temperature at which the nitrified cotton of the above solvent burns;
That is, 550°C to 600°C1, for example 580°C
The fading prevention fluorescent lamp 40W-FL4O8-N-8D uses a glass bulb heated and fired at a temperature of 'C.
L: No peeling of titanium oxide film occurs even when thickened.

It showed excellent properties by blocking light in the ultraviolet region and without decreasing optical output in the visible light region. According to experiments, the heating temperature after depositing a titanium oxide coating on the inner surface of a glass bulb is lower than 300°C when the solvent contains nitrified cotton.
There is a risk that the nitrified cotton in the titanium oxide coating will dissolve in the butyl acetate in the phosphor suspension when applying the phosphor suspension in the subsequent process, causing the titanium oxide coating to disappear. Such a phenomenon did not occur at the heating temperature. Furthermore, if the heating temperature is higher than 500° C., there is a risk that the titanium oxide coating will crack and peel off, as in the conventional case, which is not preferable.

Of the nitrified cotton and butyl acetate used as the solvent, butyl acetate vaporizes and disappears at room temperature, and about 80% of the mass of the nitrified cotton burns at 180° C., leaving about 20%. These remaining 20
% of nitrified cotton is hardly decomposed at temperatures below 300°C, so there is a risk that the remaining amount of nitrified cotton will dissolve in the butyl acetate in the phosphor suspension and the titanium oxide coating will flow out. It is preferable that the titanium coating film be heated to 300°C or higher. Furthermore, at temperatures above 300°C and below 500°C, the remaining 20% of the nitrified cotton decomposes, but a portion of the main chain, which is the main structure of the nitrified cotton, still remains. It is thought that it does not dissolve in butyl acetate and prevents cracks in the titanium oxide coating. By raising the temperature to 550° C. or higher, all of the nitrified cotton in the titanium oxide coating and the phosphor coating burns and disappears. By using not only the above-mentioned solvent but also an organic solvent such as nitrified cotton, a similar phenomenon can occur and the effects of the present invention can be achieved.

In addition, the manufacturing method of the present invention is not limited to the manufacturing of general anti-fading type fluorescent lamps as described in the embodiments, but is also applicable to fluorescent lamps of the labid start type with an internal conductive coating, in which a thin film of titanium oxide or the like is formed on the internal conductive coating. It can be applied to the manufacture of fluorescent lamps, such as lamps, which have multiple layers of metal oxide coatings on the inner surface of a glass bulb and a phosphor coating thereon.

〔Effect of the invention〕

As detailed above, the method for manufacturing the fluorescent lamp of the present invention is to apply a suspension of metal oxide powder in a solvent to the inner surface of a tubular glass bulb to form a metal oxide coating film; a step of heating the glass bulb at a temperature lower than the combustion temperature of the solvent to form the metal oxide coating; and a step of heating the glass bulb after the above step at a temperature higher than the combustion temperature of the solvent to form the coating. The metal oxide coating film does not crack or peel off when cooled after being applied and heated, and there is no decrease in light output (excellent). This invention has the advantage of being able to provide a method for manufacturing a fluorescent lamp with improved characteristics.

[Brief explanation of the drawing]

The figure is a cross-sectional view of a glass bulb as an example of a fluorescent lamp for preventing color fading. (1)...Glass bulb, (2)...
Metal oxide coating. (3)...phosphor coating.

Claims (1)

[Claims] In a method for manufacturing a fluorescent lamp in which a phosphor coating is applied to the inner surface of a tubular glass bulb via a metal oxide coating, a suspension of metal oxide powder suspended in a solvent is applied to the inner surface of the glass bulb. a step of heating the glass bulb at a temperature lower than the combustion temperature of the solvent after the above step; and a step of heating the glass bulb at a temperature higher than the combustion temperature of the solvent after the above step. 1. A method for manufacturing a fluorescent lamp, comprising the step of burning a solvent between a metal oxide coating film and a phosphor coating film to form a coating.