JPS6360502B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal halide lamp used in the field of photochemical reactions such as curing printing ink using ultraviolet rays.

In recent years, as printing technology using printing ink that cures and dries with ultraviolet rays has been developed and put into practical use, metal halide lamps with iron sealed in the arc tube are increasingly being used instead of mercury lamps as light sources for curing printing ink. It is used. Various lengths of such lamps have been developed taking into consideration the size of the irradiated object such as printed matter, but the effective width of the UV irradiation of this lamp depends on the lamp's tube axis length and the type of printing ink. Although it varies somewhat depending on the situation, it is usually about 80 to 90% of the lamp light emission length. This is because the amount of ultraviolet radiation at the ends of the lamp tube drops sharply compared to the center, so the effective width of ultraviolet rays on the irradiated object becomes narrower than the length of the lamp's light emission. This is due to this. In other words, this is because the rate of decrease in ultraviolet light intensity relative to the initial stage of lighting is small at the center of the lamp, but the rate of decrease is significantly large at the ends of the tube. Moreover, in addition to the fact that the UV intensity at the end of the tube is originally low, the blackening that occurs near the electrode while the lamp is on accelerates the decrease in the UV intensity at the end of the tube, and as a result, the end of the printed matter In this case, drying of the printing ink often occurs, and the drying process tends to become unstable. In particular, blackening at the end of the tube will cause problems such as the shorter the tube axis of the lamp, the lower the intensity of ultraviolet light in the center of the lamp, which will adversely affect the curing and drying of printing ink. .

The present invention was developed based on the above circumstances, and its purpose is to prevent blackening of the end of the tube, expand the effective irradiation width of ultraviolet rays on the object to be irradiated, and provide reliable ultraviolet rays. The present invention aims to provide a metal halide lamp for photochemical reactions with high performance.

The present invention will be explained below based on an embodiment shown in the drawings. In the figure, reference numeral 1 denotes an arc tube made of quartz glass, and electrodes 2, 2 are provided at both ends of the arc tube 1, respectively. These electrodes 2, 2 are metal foil conductors 4, which are sealed within the crushing sealing parts 3, 3 of the arc tube 1.
4 to lead wires 5, 5, respectively. The arc tube 1 in this embodiment has an inner diameter of
22mm, effective light emitting length 250mm, lamp voltage 290~340V,
A lamp with a lamp current of 7.6A and a lamp power of 2000W is used, and the arc tube 1 contains 150mg of mercury and 8.8mg of mercury iodide.
For example, add 1 mg, 5.2 mg of iron, and zirconium (Zr) so that the gram atomic ratio to the above iron is 2 or less.
In addition, argon is added as a rare gas for starting.
10 Torr is enclosed.

Next, the operation of the above configuration will be explained in detail based on experimental results. The present inventors conducted various experiments on metal halide lamps filled with iron, and found that by filling zirconium in the arc tube 1 so that the atomic ratio to iron was 2 or less, zirconium It has been found that blackening of the tube end of the lamp can be prevented without almost any visible luminescence and without causing any major changes in the luminescent properties of iron. That is, a lamp constructed as described above and a conventional lamp not filled with zirconium were used, respectively.
After lighting for 1000 hours, the intensity of ultraviolet rays along the tube axis direction of both lamps was measured on the irradiated surface of the irradiated object, and the experimental results shown in FIG. 2 were obtained. Curve A in FIG. 2 shows the ultraviolet light intensity distribution from the center of the lamp to the end of the tube when the lighting time is 0 hours, and the curve B shows the ultraviolet light intensity distribution after the lighting time of 1000 hours from the lamp according to the present invention. Curve C shows the intensity distribution of ultraviolet light obtained from a conventional lamp after a lighting time of 1000 hours. Note that the ultraviolet intensity shown by these curves B and C is expressed as a relative value when the ultraviolet intensity obtained from a lamp that has been lit for 0 hours is taken as 100%. As is clear from Figure 2, conventional lamps generally have a large rate of decrease in UV intensity, and the rate of decrease at the ends of the tube is significantly greater than that at the center. Lamps generally have a lower rate of decline in UV intensity.
It was found that the rate of decrease was as small as about 10%, and that the rate of decline at the ends of the tube in particular was almost the same as that at the center. Although the exact mechanism behind this is not clear,
It is presumed that zirconium adsorbs the hydrogen component released into the arc tube 1 and acts as a getter, thereby preventing blackening of the tube end. Therefore, as can be seen from the above explanation, by filling the arc tube 1 with zirconium, the ultraviolet output along the tube axis direction of the lamp is greatly improved, and the effective irradiation width of ultraviolet rays on the irradiated object is increased. It has the advantage of expanding
This allows stable drying of printing ink and the like.

Note that the present invention is not limited to the above embodiments. That is, when the present inventors sealed titanium in place of the zirconium in the arc tube 1 so that the atomic ratio to iron was 2 or less, the luminescence of this titanium was hardly observed and the luminescence characteristics were also large compared to that of iron. It has been found that blackening of the tube end can be prevented without causing any change. Even in this case, it is presumed that the blackening of the tube end is prevented by the getter action of titanium.

Furthermore, it has been confirmed through experiments that even if both zirconium and titanium are sealed in the arc tube 1 at the same time, the same effect as described above can be obtained.

As described above, the present invention includes a starting gas in the arc tube,
This is a metal halide lamp that contains mercury, iron, halogen, and at least one of zirconium and titanium. According to this, by adding zirconium or titanium, the rate of decrease in ultraviolet light intensity along the tube axis direction is reduced overall, and the rate of decrease at the ends of the tube is reduced to almost the same as that at the center. can do. Therefore, the ultraviolet output of the lamp is greatly improved, and the effective irradiation width of ultraviolet rays on the object to be irradiated can be expanded.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view, and FIG. 2 is an explanatory diagram showing the ultraviolet intensity distribution along the tube axis direction of the lamp. 1... Arc tube.

Claims (1)

[Claims] 1. A metal halide lamp for photochemical reactions, characterized in that the arc tube is filled with starting gas, mercury, iron, and halogen, as well as at least one of zirconium and titanium.