JPH01161658A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To suppress blackening of a tube wall so as to improve ultraviolet ray intensity maintenance factor by charging boron at the specified gram atom number ratio to iron in addition to the iron. CONSTITUTION:Electrodes 2, 2 provided in a light emitting tube 1 are each connected to lead wires 5, 5 through metal foils 4, 4 sealed inside the crushed sealing parts 3, 3 of the light emitting tube 1. And rare gas for starting, mercury, iron and halogen are charged into the light emitting tube 1 and further boron of 1/40-1/2 at the gram atom number ratio to iron is charged. If boron B is charged additionally into the light emitting tube in advance like this, this boron reacts on the charged halogen and forms boron halide and reacts on the isolated iron and changes it into iron halide. Hereby, tube wall blackening due to adhesion of iron to the tube inside wall is suppressed and lowering of an ultraviolet ray intensity maintenance factor resulting from the decrease of ultraviolet ray transmissivity by blackening and the decrease of iron being a light emitting metal can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a metalnolide lamp used in the field of photochemical reactions, such as curing printing ink, using ultraviolet rays.

(Prior art) Metal halide lamps are made by sealing iron and halogen together with a starting rare gas and mercury in the arc tube.

Because it has excellent luminous efficiency in ultraviolet light, particularly in the UV-A region (315 to 400 nm), it is often used in place of mercury lamps as a light source for photochemical reactions, such as curing printing ink.

However, this lamp has the drawback that as the lighting time elapses, a black compound is deposited on the inner wall of the arc tube, and the maintenance rate of ultraviolet light intensity is extremely reduced.

To address these drawbacks, for example, Japanese Patent Application Laid-Open No. 57-637
No. 57, Japanese Patent Application Laid-Open No. 57-101329, etc., disclose means for suppressing the blackening of the tube wall by adding palladium, zirconium, titanium, etc. in addition to iron.

However, for example, when it comes to light sources used as light sources for curing printing ink, even the improved lamps mentioned above are not suitable for the recent speed-up of printing presses and the market demand for longer lifespans. He wasn't necessarily in a position to rest.

(Problems to be Solved by the Invention) As mentioned above, in conventional iron-containing metal halide lamps, the maintenance rate of ultraviolet light intensity is extremely reduced due to the blackening of the tube wall, and even in lamps that have been improved in this respect, However, it has not been able to fully meet recent market demands.

Therefore, the present invention solves the above-mentioned conventional drawbacks, and provides a metal halide lamp for photochemical reactions that further suppresses tube wall blackening and has an improved ultraviolet intensity maintenance rate that can fully meet market demands. The purpose is to provide.

[Structure of the invention]

(Means for Solving the Problems) The metal halide lamp of the present invention further contains boron (B) in addition to iron in a gram atomic ratio of 1/40 to 1/
It is configured to enclose two parts.

(Function) According to the analysis results, the black compound is iron, and it is presumed that the iron sealed in the arc tube as a luminescent substance evaporates and adheres to the inner wall of the tube, which appears as a blackening phenomenon. It is not clear why the iron adheres to the inner wall of the pipe, but the iron halide produced by the reaction of iron with the encapsulated halogen (including cases where the iron was encapsulated as iron halide from the beginning) evaporates. It is assumed that iron ions dissociate into iron ions and halogen ions in the plasma during discharge, and the liberated iron ions diffuse toward the inner wall of the tube and adhere to the inner wall of the tube before combining with halogen again. .

Therefore, in order to suppress the blackening of the tube wall, that is, the adhesion of iron to the inner wall of the tube, it is sufficient to reduce the iron ions near the inner wall of the tube. If this is done, this boron reacts with the encapsulated halogen to form boron halide, so it may be encapsulated as boron halide from the beginning. ), this boron halide reacts with the liberated iron and converts it into iron halide as shown in the following formula, which prevents iron from adhering to the inner wall of the tube and causing blackening. In addition, one example of the formula is when, for example, chlorine C1 is used as the halogen, and (g) indicates a gaseous state.

2E3c13 (g) + 3Fe (g) -> 3
FeC1z (g) +2B (g) In the above reaction formula, liberated boron (B) is produced, but since B has a higher vapor pressure than Fe, it is difficult to adhere to the inner wall of the pipe, and therefore halogen It is thought that blackening can be prevented by recombining with and repeating the reaction shown in the above formula.

(Example) The present invention will be described in detail below based on an example shown in one drawing. FIG. 1 shows a schematic configuration explanatory diagram of an embodiment of the present invention, in which (1) is a quartz glass arc tube with an inner diameter of 20mm, and electrodes ( 2), (2) is provided. These electrodes (
2) , (2) is the crushing sealing part f31 of 1 arc tube (1)
, (3) Metal foil sealed inside +4) , (4)
The lead wires (51, (5) are respectively connected to the lead wires (51, (5)) through the lead wires (51, (5)). (6) and f61 are, for example, ceramic caps, and these caps are used by being held in a device (not shown). In addition, 1 arc tube (1) contains a rare gas for starting, such as argon gas Ar15), mercury Hg 1.2
m97 cc, iron halides such as iron chloride Fe (J
20.02 m/cc and a boron halide such as boron chloride BCl30.0019 m/cc are enclosed. Therefore, boron (B) is encapsulated in a gram atomic ratio of about 1/10 to iron (Fe).

There are three types of lamps: the lamp of the present invention having such a configuration, the previously mentioned conventional lamp filled with only iron (Conventional Example 1), and the conventional lamp filled with palladium, zirconium, or titanium in addition to iron (Conventional Example 2). 2 lamps each
Four lamps were turned on at a rated input of 13.2 Kw, and a comparative test of the maintenance rate of ultraviolet intensity was conducted. The results are shown in FIG. As is clear from the figure, there is no difference in the ultraviolet intensity of each lamp at the initial stage of lighting, but as one lighting time elapses, the difference between the lamp of the present invention and each conventional lamp becomes obvious.
After 2000 hours, the maintenance rate of the lamp of the present invention is 90%.
(assuming an initial value of 100), whereas in Conventional Example 2 it was about 80% and in Conventional Example 1 it was about 60%.

The amount of boron enclosed is preferably 1740 to 1/2 in terms of gram atomic ratio to iron; if the amount is increased beyond this range, the luminous efficiency of ultraviolet rays will decrease, while if it is too small, the tube wall will darken. It was confirmed that the prevention effect decreased.

〔Effect of the invention〕

As detailed above, according to the configuration of the present invention, it is possible to suppress the blackening of the tube wall due to adhesion of the iron sealed in the arc tube to the inner wall of the tube for two-emission synthesis, thereby reducing the ultraviolet green transmittance due to blackening. In addition, it is possible to prevent a significant decrease in the maintenance rate of ultraviolet light intensity due to a decrease in iron, which is a luminescent metal, and to obtain a long-life metal halide lamp for photochemical reactions that can fully meet recent market demands. .

[Brief explanation of the drawing]

FIG. 1 is a schematic structural explanatory diagram of one embodiment of the metal halide lamp of the present invention, and FIG. 2 shows a comparison curve of the ultraviolet intensity maintenance rate between the lamp of the present invention and a conventional lamp. (1)... Arc tube, (2)... Electrode.

Claims (1)

[Claims] In addition to enclosing a starting rare gas, mercury, iron, and halogen in the arc tube, a gram atomic ratio of 1
A metal halide lamp characterized by containing boron of 40 to 1/2.