JPH10275560A - Manufacture of metal halide pellet for metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the size of a pellet in the manufacture of the pellet of metal halide to be sealed in a bulb as a light emitting source so as to efficiently manufacture metal halide lamp having high luminance. SOLUTION: In the manufacture of a metal halide pellet to be sealed in a bulb as a light emitting source of metal halide lamp, one end of a quartz straight and a narrow tube is dipped in the molten metal halide bath, and pressure at the other end thereof is reduced so that the molten metal halide is sucked and led into the quartz straight and narrow tube, and after the molten metal halide is solidified, the solidified metal halide is taken out of one end of the quartz straight and narrow tube so as to form a rod of the metal halide, and this rod of the metal halide is cut at the predetermined length so as to form the metal halide pellet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing metal halide pellets, which are enclosed in a bulb as a light source when producing a high-luminance metal halide lamp having excellent color rendering properties.

[0002]

2. Description of the Related Art Conventionally, metal halide pellets used as a light source of a metal halide lamp for lighting are:
As described in JP-B-58-20889, in order to obtain product pellets having a desired metal halide composition, the respective metal halides constituting the product pellets are mixed according to a predetermined compounding composition, and this mixture is mixed. After melting in a purification vessel placed in an active gas, it is purified by subjecting it to gas washing, deaeration, etc., and then pressurized by pressurizing argon into the purification vessel and filtering using a glass filter. , Sent to the forming funnel. A nozzle having a predetermined diameter according to the desired pellet weight is attached to the molding funnel, and the molten metal halide droplets dropped from this nozzle solidify while falling in the condensation section to form pellets formed. It is manufactured by collecting in a collection bottle.

[0003]

Conventionally, metal halide lamps have been used exclusively as light sources for lighting such as industrial lighting (especially fish-collecting lights) and outdoor lighting (night lighting of stadiums, roads, etc.). In applications, high illuminance is generally required, but the color tone of the illumination light is strictly color rendering,
Or, the reproducibility was not particularly strictly required. However, in recent years, so-called light-ups have been widely performed to enhance the value of buildings by illuminating the buildings at night, and at the same time, the light-up light has been used to improve the color and shape of the buildings. Atmosphere,
Or, emphasis has been placed on good harmony with the environment surrounding buildings, and illumination light with excellent color rendering properties has been required. As a result of research and development on various metal halides to address these requirements,
For example, in terms of molar ratio, ScI ₃ / NaI = 1/6 to 1/1
It has been found that the metal halide lamp using scandium-sodium iodide having the composition of No. 4 sufficiently satisfies the color rendering required by the light-up light source. However, scandium-sodium iodide having the above composition is a very fragile crystal, and easily breaks even when a slight force is applied. Therefore, this kind of crystalline metal halide in the production process of metal halide pellets is used. Great care must be taken to ensure that unexpected external forces are not applied to the handle. However, since the weight of a metal halide pellet used for a high-intensity metal halide lamp used for outdoor lighting reaches 30 mg, a metal halide pellet having the above molar ratio composition is manufactured by a conventional method when manufacturing a metal halide pellet having the above molar ratio. When molten metal halide droplets are dropped and dropped in the condensation section, the solidified pellets gain a considerable drop speed and fall directly into the collection bottle, so it is considerably affected by the impact at the time of landing It is inevitable that the production yield will be significantly reduced due to the breakage of the solidified particles.

On the other hand, a method for producing a metal halide to be enclosed in a metal halide lamp without giving an impact to a pellet is disclosed in JP-A-3-26164 and JP-A-3-261665. Is disclosed. Here, a metal halide is melted in an inert gas atmosphere, and one end of a capillary, such as quartz, synthetic quartz, zirconia, tungsten, or molybdenum open at both ends, is immersed upright in this molten salt bath to cause a capillary phenomenon. A metal halide molten salt is filled in a thin tube by utilizing the above method, and after cooling the thin tube, the tube is cut into a desired length to fill the thin tube with a metal halide having a predetermined weight. A method of providing a metal halide in a form to be enclosed in a tube as a light-emitting source is described. However, since the method described in the above-mentioned publication uses a very thin tube having an inner diameter of 0.2 mm, a small metal halide pellet used for a metal halide lamp for indoor lighting that does not require high luminance (weight: 0.01 to 1. 0 mg) is a very suitable method, but has a weight of 30 m
The production of metal halide pellets as large as g can be difficult.

Therefore, in order to manufacture a high-luminance metal halide lamp having excellent color rendering properties, it is necessary to manufacture small pellets by a conventional method and enclose a large number of pellets in a tube. This hinders efficient production of a metal halide lamp with high brightness. For this reason, there is a strong demand for the development of a method for producing large pellets using metal halides having weak mechanical properties.

[0006]

Accordingly, the present inventors have solved the above-mentioned problems and have conducted research on manufacturing large pellets using metal halides having low mechanical strength. As a result, the molten salt was solidified. Since the glassy metal halide produced by the above method has a larger coefficient of thermal expansion than quartz and poor wettability with quartz, if the inner diameter of the quartz tube is a certain size, for example, 0.5 mm or more, the metal After the halide is filled in the quartz tube and solidified, the temperature is lowered to room temperature, and the solidified metal halide is removed from the inner surface of the quartz tube by the difference in the coefficient of thermal expansion between quartz and the metal halide. When a quartz tube having a high straightness (hereinafter, referred to as a quartz tube) is used, a metal halide is extruded from one end of the quartz tube or sucked. And, the metal halide is was found that can be easily taken out in a quartz tube outside as a rod-like rod. Then, by cutting the metal halide rod thus formed, a metal halide pellet having a desired weight can be produced with high yield without breaking the brittle metal halide.

The present invention has been made on the basis of the above-mentioned findings. In a method for producing a metal halide pellet sealed in a bulb as a light emitting source when producing a metal halide lamp, the inner diameter is 0.5 to 1.5 mm. After immersing one end of the quartz straight tube in a molten metal halide bath and depressurizing the other end of the tube, the molten metal halide is sucked and introduced into the quartz straight tube, and solidified. A method for producing a halide pellet for a metal halide lamp, wherein the halide is taken out from one end of the quartz straight tube at room temperature to obtain a rod made of a metal halide, and the rod of the metal halide is cut into a predetermined length to obtain a metal halide pellet. It is characterized by the following.

In the above-mentioned manufacturing method, when the molten metal halide is sucked and introduced into the quartz straight tube, the quartz straight tube whose both ends are decompressed is replaced with a quartz straight tube whose inside is reduced in pressure. Using a thin tube, one end of the tube is immersed in a molten metal halide bath, and the immersed end is broken in the molten metal halide bath to introduce the molten metal halide into the quartz straight tube, so that the inside of the tube is a metal halide. It is also possible to form a quartz straight tube filled with the above, and to cut the metal halide solidified in the quartz straight tube from the quartz straight tube with a laser cutting machine to form a metal halide pellet, Halogen for metal halide lamps that manufacture pellets from fragile metal halides that are easily damaged in environments with poor workability such as It is an excellent method for manufacturing a compound pellet.

In the manufacturing method of the present invention, the inner diameter of the quartz tube used for manufacturing the metal halide rod is limited to 0.5 to 1.5 mm because the inner diameter of the quartz tube is less than 0.5 mm. If the solidification does not occur, there is no sufficient gap between the metal halide rod and the quartz tube, and it is difficult to pull out the metal halide rod from the quartz straight tube. Is 1.5m
If it exceeds m, it is difficult to design the metal halide lamp bulb when encapsulating the metal halide pellet in the bulb.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The metal halide used for the metal halide lamp has a very high hygroscopicity, and the metal halide lamp extremely dislikes the presence of water in the tube.
All operations for producing pellets from metal halide powders are performed in a glove box in an argon atmosphere adjusted to a steam pressure of 0.3 Pa or less. Therefore, an apparatus for producing pellets from metal halide powder (main equipment is an electric furnace for melting metal halide powder, a vacuum pump for sucking molten metal halide into a quartz tube, metal (Including diamond cutters and laser cutters for cutting halide rods) are all provided in the glove box, and none of these devices can release moisture.

The raw material for producing the metal halide pellets of the present invention is preferably a metal halide having a high purity and an extremely small water content.
The metal halide produced by the production method disclosed in 92633 is very suitable as a raw material for the method of the present invention.

The metal halide produced by the above-described method, for example, a raw metal halide such as ScI ₃ or NaI, is used in order to produce a metal halide pellet having a composition corresponding to a desired color rendering property of a metal halide lamp. Is prepared, charged into a quartz crucible, heated and melted using an electric furnace, and mixed homogeneously. Then, one end of a thin tube of high straightness made of thick transparent quartz having an inner diameter of 0.5 to 1.5 mm and having an inner diameter as uniform as possible and having an extremely clean and dry inner surface is flexible. The other end is immersed in a molten metal halide bath via a conduit, the other end is immersed in a molten metal halide bath, and the depressurizer is operated to suck the molten metal halide and introduce it into a quartz straight tube. At this time, if the quartz straight tube is heated in advance, the molten metal halide is prevented from cooling and solidifying as it rises in the tube, so that a long rod can be manufactured.

[0013] After filling the quartz straight tube with the molten metal halide in this way, the quartz straight tube is cooled to solidify the metal halide in the quartz straight tube, and then cooled to room temperature. Is reduced by about 5% during solidification, and in the cooling process to room temperature, the scandium-sodium iodide shrinks by about 5% to the inner diameter of the metal halide quartz straight tube by cooling to room temperature. I do. Therefore, the metal halide in the tube can be easily taken out from the quartz straight tube by pushing out / or sucking from one end, and can be made into a rod. If the rod manufactured in this manner is cut using a diamond cutter or a laser cutter, pellets can be easily manufactured even with highly brittle metal halides. Furthermore, in the case of extremely brittle metal halide, a solidified metal halide is extruded at a constant speed by inserting a tungsten wire or the like at a constant speed from one end of a straight quartz tube, and the extruded metal halide is irradiated with a laser. By cutting at regular intervals using a cutting machine, pellets with a constant weight can be efficiently produced.

Instead of sucking and introducing the molten metal halide into the quartz straight tube using a vacuum pump in the glove box, one end of the quartz straight tube whose both ends have been sealed in advance by reducing the internal pressure to a high degree. Is immersed in a molten metal halide, and if the immersed end is broken in a molten metal halide bath, the molten metal halide is immediately sucked into the quartz straight tube due to the negative pressure in the quartz straight tube, and the metal is sucked. A quartz straight tube filled with halide is formed. In general, it is extremely difficult to increase the efficiency of manual operations performed in a glove box. Therefore, this method that can greatly reduce the operations in the glove box is a very useful method for increasing work efficiency.

[0015]

Next, the method of the present invention will be described in more detail with reference to examples.

Embodiment 1 First, Japanese Patent Laid-Open No. 6-92633
Powdered metal halide: ScI ₃ , Na, prepared using the method disclosed in US Pat.
I was prepared.

Next, the prepared metal halide powder:
While containing ScI ₃ and NaI in an ampoule, they were carried into a glove box under an argon gas atmosphere controlled at a water vapor pressure of 0.3 Pa or less, and opened there.
The mixed powders a to c were prepared by mixing the metal halides in the proportions shown in Table 1, added to a transparent quartz crucible having a capacity of 200 ml, and heated in an electric furnace using a sheath heater as a heating source.
Melting produced a molten metal halide having the desired composition.

[0018]

[Table 1] Next, a ribbon heater was attached to a thick transparent quartz thin tube having a diameter shown in Table 2 prepared in advance and having an outer diameter of about 0.9 cm and a length of 50 cm, and was attached to one end of the quartz straight tube. A hose made of silicon rubber led from a suction hole of a vacuum pump through a reservoir was connected, and attached to an elevating device provided above a transparent quartz crucible. Then, by energizing the ribbon heater, the transparent quartz tube was heated to 200 ° C., and then the reservoir was depressurized by operating a vacuum pump. Then, the quartz straight tube was lowered by the elevating device to lower the lower end of the quartz straight tube. After being immersed in the molten metal halide bath held by the transparent crucible, the reservoir and the quartz straight tube are connected, the molten metal halide is sucked into the quartz straight tube, and the length of the narrow tube is filled with the metal halide over about 40 cm. Was. After the energization of the ribbon heater was stopped, it was confirmed that the metal halide in the quartz straight tube was completely solidified, and the quartz straight tube was removed from the elevating device and the suction system, and cooled to room temperature.

The quartz straight tube cooled to room temperature inserts a tungsten wire from one end on the suction side, pushes out a metal halide rod, attaches the rod to an automatic feeder, cuts it with a diamond cutter, and cuts the pellet. The weight of the sample pellets produced and collected is measured, and the average weight and the ratio of the pellets having a weight in the range of ± 10% of the average weight to the whole (hereinafter referred to as 10% section) are obtained to obtain the values shown in Table 2. Was.

[0020]

[Table 2] Example 2 As the raw materials, the same metal halides as used in Example 1 were used: ScI ₃ and NaI.

First, a length having an inner diameter shown in Table 3: 50
cm of quartz straight tubes were prepared, each of which was evacuated to the pressure shown in Table 3 using a vacuum pump. Both ends were sealed as they were and cut at one end to form a shape easily broken. Then, this quartz straight tube was introduced into a glove box, and the entire tube was immersed in 200 g by using a ribbon heater.
After preheating to ℃, one end is immersed in a molten metal halide bath prepared using raw metal halide mixed powders a to e in a mixing ratio shown in Table 1 prepared in advance, and a jig made of metal tungsten is used. Then, one end was broken in a bath, and the molten metal halide was introduced into the quartz straight tube to form a quartz straight tube filled with the metal halide. Next, the quartz straight tube was cooled to room temperature, and both ends were cut off by 10 cm each. A tungsten wire was inserted from one end at the speed shown in Table 3 to push out the metal halide rod from the other end. Meanwhile, the rod was cut using a laser cutting machine to obtain a metal halide pellet. A sample was collected from the thus-produced metal halide pellet, and the weight of each pellet of the sample was measured. The average weight and the 10% fraction of the average weight were determined to obtain the values shown in Table 3.

[0022]

[Table 3] Comparative Example Next, for comparison, Japanese Patent Publication No. 58-20889.
Using mixed powders a to c prepared in the proportions shown in Table 1 based on the method disclosed in
Metal halide pellets were produced by conventional methods.

50 g of the mixed powder shown in Table 4 was collected in a quartz crucible, melted, washed by passing an inert gas, and filtered using a No. 3 silica frit filter. The molten metal halide was sent to the funnel while the nozzle was filled with helium gas as droplets from a nozzle provided at the bottom of the funnel and having a diameter shown in Table 4. Length: 30
The solution was dropped into a condensing section composed of a quartz cooling cylinder having a diameter of 0 cm and a diameter of 10 cm. A collecting bottle was attached to the lower part of the condensing section in communication with the cooling cylinder, and the pellets solidified in the condensing section were collected by the collecting bottle. A sample was collected from the collected pellets by the 4-minute method, the particle size distribution was determined by the sieving method, converted to the weight distribution of the particles by calculation, and the mode and 10% fraction of the weight were determined. Value.

[0024]

[Table 4]

[0025]

As shown in Table 4, the metal halide was obtained by the conventional method.
When the oxide pellets are manufactured, ScI _Three/ Mol of NaI
In the range of 1/6 to 1/14, the product pellet
When the weight mode is 1 mg, 30% or more pellets
Is in the 10% zone, but is required for lighting up
Used for metal halide lamps with different color tones
I_Three/ NaI molar ratio composition: within the range of 1/6 to 2,
When using a funnel with a nozzle of the same diameter, 10%
The stroke is only 10% and has a weight of 1 mg.
It is extremely difficult to produce a kit. In contrast
Therefore, as is apparent from Tables 2 and 3, the method of the present invention is used.
The metal halide pellets produced by
cI_ThreeTo the average weight of the particles regardless of the ratio of
Most of the particles are present in the ± 10% section.

According to the method of the present invention, it is possible to produce a large-weight pellet of scandium-sodium iodide having an extremely wide composition range, and has excellent color rendering properties that can meet the requirements of outdoor lighting such as light-up of a building. Its industrial utility is extremely large, for example, it is possible to produce a high brightness metal halide lamp.

Claims (4)

[Claims] 1. A method for producing a metal halide pellet which is enclosed in a bulb as a light source when producing a metal halide lamp, wherein one end of a quartz tube is immersed in a molten metal halide bath and the other end is depressurized and melted. The metal halide is sucked and introduced into the quartz tube to form a quartz tube whose inside is filled with a metal halide, which is cooled to solidify the metal halide in the tube, and then solidified in the quartz tube. Is extracted from one end of a quartz tube to form a rod made of a metal halide, and the metal halide rod is cut into a predetermined length to form a pellet, thereby producing a metal halide pellet for a metal halide lamp. 2. An end of a quartz tube whose both ends are sealed under reduced pressure is immersed in a molten metal halide bath, and the immersed end is broken in the molten metal halide bath to remove the molten metal halide in the quartz tube. A quartz tube filled with a metal halide in the tube.
A method for producing a metal halide pellet for a metal halide lamp as described above. 3. The metal halide solidified in the quartz tube is cut by using a laser cutter while being extruded from one end of the quartz tube to form metal halide particles having a predetermined weight. Of producing metal halide pellets for metal halide lamps. 4. The quartz tube has an inner diameter of 0.5 mm to 1.5 mm.
The method for producing a metal halide pellet for a metal halide lamp according to claim 1, wherein