JP2991901B2 - Ultraviolet absorbing silica glass and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a silica glass excellent in devitrification resistance, particularly to an ultraviolet absorbing silica glass for a discharge tube and a high-intensity discharge lamp bulb material, and a method for producing the same .

[0002]

2. Description of the Related Art Conventionally, in the field of the lighting industry, silica glass, particularly so-called "fused quartz glass" obtained by electromelting natural quartz has been used as a material for various discharge tubes. However, this fused silica glass has a high transmittance of ultraviolet rays, and a discharge tube made of this fused silica glass has a drawback that ozone harmful to the human body is generated from oxygen in the air because ultraviolet rays are transmitted well. Therefore, Ti, V, Cr, M
Ultraviolet-absorbing silica glass doped with n, Fe, Co, Ni, Cu or Ce has been developed, which is disclosed, for example, in JP-B-39-21056 and JP-B-46-42114.
JP-A-5-89280 and JP-A-5-89280
4-79978.

[0003] However, the silica glass described in the above publication absorbs ultraviolet light having a wavelength of about 220 nm or less, but has poor absorption of ultraviolet light having a wavelength longer than that. The long-wavelength ultraviolet light generated at the time of the light emission damages human eyes and significantly degrades a plastics member constituting an automobile headlight. In addition, the above silica glass has a high OH group and hydrogen molecule concentration,
In the high-intensity discharge lamp produced therefrom, the luminous gas sealed in the bulb material reacts with oxygen generated from the OH group to cause black devitrification, or hydrogen molecules increase the operating voltage of the lamp, or The crystallization by the alkali metal element in the silica glass and the chemical etching by the sealing gas are promoted to cause white devitrification, and the life is short.

[0004]

In view of these circumstances, the present inventors have proposed a silica glass for a discharge tube of about 4%.
We are keen to develop UV-absorbing silica glass that absorbs ultraviolet light of 00 nm or less to prevent ozone generation, harmful effects on the human body, and deterioration of plastics, and that has little decrease in luminous efficiency as a bulb material for high-intensity discharge lamps. As a result of repeated research, the above object was achieved by limiting the OH group concentration and hydrogen molecule concentration in silica glass to specific ranges, containing a transition metal element, and controlling the ionic valence of the transition metal element. The present invention has been completed by finding out what can be done.

An object of the present invention is to provide an ultraviolet-absorbing silica glass which has excellent ultraviolet-absorbing properties and does not adversely affect the human body and does not deteriorate plastics members.

Further , the present invention provides a high-pressure mercury lamp having high heat resistance.
For high- intensity discharge lamps such as lamps and metal halide lamps
Even when used as a material, there is no thermal deformation and also devitrification resistance
An object is to provide an excellent ultraviolet absorbing silica glass.

Another object of the present invention is to provide a novel method for producing the above-mentioned ultraviolet absorbing silica glass.

[0008]

According to the present invention, there is provided an ultraviolet absorbing silica glass for a discharge tube,
When the OH group concentration is 200 wt. The present invention relates to an ultraviolet-absorbing silica glass containing at least one transition metal element having a hydrogen molecule concentration of 5 × 10 ¹⁶ molecules / cm ³ or less and having a controlled ionic valence, and a method for producing the same. .

Further, according to the present invention, when the ultraviolet absorbing silica glass for a high-intensity discharge lamp is used, its OH group concentration is 2
0 wt. ppm or less, hydrogen molecule concentration is 5 × 10 ¹⁶ mol
The present invention relates to an ultraviolet-absorbing silica glass containing at least one transition metal element having a controlled ionic valence of not more than ecules / cm ³ and a method for producing the same.

The above-mentioned transition metal elements include Ti, V, Cr,
Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo,
Tc, Ru, Ce, Pr, Nd, Pm, Sm and Eu
Of elements 22 to 29, 40 to 44 and 58 to 63 Particularly preferred transition metal elements are titanium, chromium and cerium. The content of the transition metal element is 10
-10,000 wt. ppm, and the range is 10 wt. If it is less than ppm, even if the ionic valence control process is appropriately selected, the effect of absorbing ultraviolet rays of about 400 nm or less is not observed, and 10,000 wt. Above ppm, UV absorption
Transparency in the visible region of the absorptive silica glass is deteriorated, and the light output when used as a bulb material is reduced.

The ultraviolet-absorbing silica glass of the present invention is prepared by subjecting a silica glass containing a transition metal element to an ionic valence control treatment to change the ionic valence of the transition metal element by about 400.
It is a silica glass that is controlled to absorb ultraviolet light of nm or less. The ionic valence control treatment is performed by changing the transition metal element-containing silica glass in an oxidizing atmosphere to 800 to 130.
0 ℃ In either heat treatment or ultraviolet rays, X-rays, irradiation with γ-rays means a process of oxidation.

[0012] The control of the ionic valence refers to changing the ionic valence as light transmission spectrum of the ultraviolet region of the silica glass is above about 400 nm. For example, when cerium-containing silica glass is oxidized at 800 to 1300 ° C. in an oxidizing atmosphere, it absorbs about 400 or less ultraviolet rays.

Further , the ultraviolet absorbing silica gel of the present invention
Absorbs a lot of ultraviolet light and raises the temperature of the discharge lamp bulb material
To increase the luminous efficiency of the lamp . In addition, the heat resistance of the silica glass is improved because the transition metal element is contained, and the surface temperature of the silica glass rises to about 1000 ° C. at the time of light emission. Does not occur.

By the way, O contained in silica glass
The H group is decomposed during emission of the high-intensity discharge lamp to generate oxygen, which reacts with the enclosed metal gas and the metal tungsten of the electrode to cause black devitrification. It is also said that the generation of hydrogen molecules causes a re-ignition spike voltage and an increase in operating voltage (Hiromitsu Matsuno et al. (1981) Mechanism of decrease in luminous flux maintenance rate in metal halide lamps, Journal of the Illuminating Engineering Institute, Vol. 65) , No. 4, pp. 176-181). further,
It is presumed that white devitrification occurs due to promotion of crystallization by an alkali metal element or an alkaline earth metal element in silica glass and chemical etching by a sealing gas. When black and white devitrification and an increase in operating voltage occur, the luminous efficiency of the lamp is remarkably reduced. Can be solved to some extent. However, in order to sufficiently solve these problems, including white devitrification, concretely, ultraviolet absorbing silica glass for discharge tubes is used.
In the case of the glass, the OH group concentration in the silica glass is set to 200 wt.
ppm or less, the hydrogen molecule concentration is 5 × 10 ¹⁶ molecular
It is necessary to improve the heat resistance by containing es / cm ³ or less and containing a transition metal element.

Further, 20 wt an OH group concentration when the discharge tube is a high intensity discharge lamp. ppm or less, hydrogen molecule concentration of 5
× 10 ¹⁶ molecules / cm ³ or less and a transition metal element must be contained.

The measurement of the OH group concentration is described in D. M. Dod
d, D. B. Fraser (1960), Optica
l Determinations of OH in
Fused Silica, J. et al. Applied P
physics, Vol. 37, p. 3911 (196
According to the method of 6), and the measurement of the hydrogen molecule concentration,
S. Khotimchenko, et al. (19
87) Determining the Conte
nt of Hydrogen Dissolved
in Quartz Glass Using the
Methodof Raman Scatterin
g and Mass Spectrometry,
J. Appl. Spectrosc. , Vol. 46,
No. 6, pp. 632 to 635.

[0017] ultraviolet thus about 400mm absorbs UV light below, and the present invention having excellent properties in resistance to devitrification
The line absorbing silica glass is produced by the following means. That is, quartz powder is mixed with a transition metal compound, for example, a compound such as chloride, iodide, carbonate, or nitrate, and the mixed material is vitrified by a vacuum electric melting method, or the transition metal element compound and tetrachloride are mixed. The mixture with silicon is vitrified by the soot method of the oxyhydrogen flame hydrolysis method, and then this silica glass is subjected to an ionic valence control treatment to make the ionic valence of the transition metal element in the silica glass to a required value. Manufactured by controlling
Is done .

In the above production, the mixing of the transition metal element compound with the quartz powder, which is a raw material of silica glass, is carried out by using an aqueous solution if the transition metal compound is water-soluble, or by adjusting the particle size if the transition metal compound is insoluble solid particles. The means of mixing is chosen . Especially hitting the vitrified in a vacuum electric melting method transition metal source
The raw material of silica glass mixed with elemental compound
Pre-treatment at about 1000 ° C.
It is preferable to adjust the water content with
When mixing with an aqueous solution, it is important to perform the pretreatment.
You .

On the other hand, in the case of vitrification by the soot method of the oxyhydrogen flame hydrolysis method, the soot body before transparent vitrification is dehydrated in a chlorine or hydrogen chloride gas atmosphere to obtain a water content.
And adjust the OH group and hydrogen molecule concentration.
Good .

Hereinafter, the present invention will be described more specifically with reference to examples.

EXAMPLES (1) Preparation of silica glass In Examples 1 to 5, natural quartz powder was used in a particle size of 10 to 100.
μm, and a high-purity treatment of heating in a chlorine gas atmosphere is performed to make the SiO ₂ purity 99.999 wt. %. Next, a purity of 99.99 wt. % Of each oxide powder of titanium, cerium and chromium was mixed. The mixed powder was kept at 200 ° C., and further kept at 1000 ° C., and after adjusting the water content, transparent vitrification was performed by a vacuum electric melting method. The obtained transition metal element-containing silica glass was subjected to a heat oxidation treatment at 1100 ° C. for 100 hours in the air or a γ-ray irradiation treatment using Co-60 to perform an ion valence control treatment. The physical properties of the silica glass subjected to the ion valence control treatment were evaluated, and the results are shown in Table 1.

In Example 6, the mixed powder prepared in the same manner as in the above example was transparently vitrified by an oxyhydrogen flame Bernoulli method. The obtained transition metal element-containing silica glass was irradiated with γ-rays using Co-60 to perform an ion valence control process. The physical properties of the silica glass subjected to the ion valence control treatment were evaluated, and the results are shown in Table 1 .

In Examples 7 and 8, cerium and titanium chloride were mixed with high-purity silicon tetrachloride as a silica raw material. Next, a soot body was prepared from this mixed raw material by the soot method of oxyhydrogen flame hydrolysis. This soot body was subjected to a heat treatment in a chlorine gas atmosphere to reduce moisture. This dehydrated soot body was heat-treated in a vacuum to obtain a transparent glass. Further, the obtained transition metal element-containing silica glass was heated and oxidized at 1,100 ° C. for 100 hours in the air to perform an ion valence control process. The physical properties of the silica glass subjected to the ion valence control treatment were evaluated, and the results are shown in Table 1.

For comparison, the silica glass which was not appropriately subjected to the ion valence control treatment of the present invention or which was performed in a reducing atmosphere , and M-382 manufactured by Shin-Etsu Quartz Co., Ltd.
Physical properties were evaluated in the same manner as in the Examples, and the results were compared with Comparative Examples 1 to 1.
4 is shown in Table 1.

(2) Measurement of physical property values-Measurement of OH group concentration; measured by infrared absorption spectrophotometry (DM Dodd, et al. (1987), supra)
reference). -Measurement of hydrogen molecule concentration; Raman scattering method (see VS.
Khotim-chenko, et al. (198
7)). -Measurement of transition metal element concentration; measured by atomic absorption spectrophotometry. -Measurement of light transmission wavelength range: 190 mm to 900 nm of a sample having a thickness of 2 mm and mirror-polished on both sides with a light transmittance meter
Measure light in the range. Ampoule test: A tube having a diameter of 10 mm, a thickness of 2 mm and a length of 100 mm was prepared, and one end of the tube was roundly sealed to form a test tube. Next, DyI ₃ particles were introduced into the dried glove box. The tube was evacuated, and the other end was rounded to form an ampule. This was heated at 1100 ° C. for 100 hours, taken out of the furnace, and visually observed for the degree of white devitrification on the inner wall of the ampoule.

[0025]

[Table 1]

As shown in Table 1 above, the ultraviolet absorption of the present invention was
Sex silica glass well absorb about 400nm UV light below, yet the generation of white devitrification little.

[0027]

The ultraviolet-absorbing silica glass of the present invention comprises:
Excellent ultraviolet absorption and devitrification resistance, useful as a discharge lamp material for automotive headlights, projectors and general lighting, and also as a bulb material for high-intensity discharge lamps such as metal halide lamps It is .

Continued on the front page (72) Inventor Mitsuha Kuriyama 88, Kawakubo, Kanaya, Tamura-cho, Koriyama-shi, Fukushima Shin-Etsu Quartz Co., Ltd. References JP-A-4-231343 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C03C 4/08 C03B 20/00 C03C 3/06

Claims (10)

(57) [Claims] 1. An ultraviolet absorbing silica glass for a discharge tube, wherein the OH group concentration is 200 wt. ppm or less, purple, characterized in that at least one is contained in the transition metal elements hydrogen molecule concentration is 5 × 10 ¹⁶ molecules / cm ³ or less, and has controlled the ionic valence
External ray absorbing silica glass. 2. An ultraviolet-absorbing silica glass for a high-intensity discharge lamp bulb material, which has an OH group concentration of 20 wt. pp
m or less, and the hydrogen molecule concentration is 5 × 10 ¹⁶ molecules
An ultraviolet-absorbing silica glass containing at least one transition metal element having a controlled ionic valence of at most / cm ³ . 3. The content of the transition metal element is 10 to 10,000.
0 wt. The ultraviolet absorbing silica glass according to claim 1 or 2, wherein the content is ppm. 4. The ultraviolet absorbing silica glass according to claim 1, wherein a mixture of the quartz powder and the transition metal element compound is vitrified by a vacuum electric melting method. 5. The ultraviolet absorbing sheet according to claim 1, wherein a mixture of silicon tetrachloride and a transition metal element compound is vitrified by a soot method of oxyhydrogen flame hydrolysis. /> Lika glass. 6. The ultraviolet according to claim 1, wherein the transition metal element is at least one element selected from titanium, chromium and cerium.
Line absorbing silica glass. 7. The ultraviolet absorbent silicone according to claim 1 or 2.
In the production process of Kaglass, the raw material of silica glass and
Moisture in mixture with at least one transition metal element compound
After adjusting the amount, it is melted and vitrified to form a transparent silica glass.
And then heat treatment or irradiation in an oxidizing atmosphere
Control the valence of transition metal elements contained
For producing ultraviolet-absorbing silica glass characterized by the following:
Law . 8. The ultraviolet absorbent silicone according to claim 1 or 2.
In a method for producing kagurasu, at least one kind of quartz powder
Water content of mixtures with certain transition metal compounds
After that, melt vitrification was performed by the vacuum electric melting method.
Heat treatment at 800 ~ 1300 ℃ in oxidizing atmosphere
Or irradiate radiation selected from ultraviolet rays, X-rays and γ-rays.
Controlling the valence of transition metal elements contained in radiation
A method for producing a UV-absorbing silica glass, comprising: 9. The ultraviolet absorbent silicone according to claim 1 or 2.
In the production method of Kaglass, high purity silicon tetrachloride and
A mixture with at least one transition metal element compound
A soot body is prepared by a soot method of a flame hydrolysis method.
The body was heated in a chlorine gas atmosphere to adjust the water content.
That is, heat treatment is performed in a vacuum to form a molten glass, and then an oxidizing atmosphere
Heat treatment at 800-1300 ° C in an atmosphere or purple
Irradiation selected from external rays, X-rays and γ-rays
Controlling the valence of transition metal elements
Of producing ultraviolet absorbing silica glass. 10. The transition metal element compound is titanium, chromium or titanium.
Is a compound of cerium.
10. The ultraviolet-absorbing silica glass according to any one of claims 9 to 9.
Manufacturing method . [0001]