JP2000239025A - Glass manufacturing method for optical parts - Google Patents

Abstract

(57) [Problem] To provide a method for producing glass for optical parts. The production method according to the present invention comprises the steps of adding nitrogen to a porous glass body mainly containing silicon dioxide containing at least one of a metal oxide and an anion under a nitrogen-containing atom-reducing atmosphere. In the method for producing a transparent glass for optical parts containing 0.3% by weight or more of nitrogen atoms by vitrifying the glass, the metal oxide or the anion may have a softening temperature of 140%.
It is characterized by being added so as to be 0 ° C. or more and 1700 ° C. or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing glass for optical parts. More specifically, a nitrogen atom of 0.3
Softening temperature of 1400 ° C or more and 170% by weight or more
The present invention relates to a method for producing a transparent glass for optical parts having a temperature of 0 ° C. or lower.

[0002]

2. Description of the Related Art It is known to add nitrogen to raise the refractive index of quartz glass for optical components. It is also known that the addition of nitrogen increases the softening temperature of the glass and improves the so-called high-temperature durability.

On the other hand, from the viewpoint that such nitrogen-added glass is processed into various optical parts, the property that the softening temperature is excessively increased is not always preferable.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the nitrogen-added quartz glass described above, and is an economical nitrogen-added glass with good workability.
Provided is a method for producing quartz glass for optical components having good optical characteristics (high refractive index).

[0005]

Means for Solving the Problems The present inventors have made intensive studies and have found a method capable of lowering the softening temperature while maintaining the refractive index of nitrogen-added quartz glass at a predetermined value, and have completed the present invention. By using the manufacturing method according to the present invention,
It is possible to economically produce transparent glass for optical components having good optical properties and workability.

That is, the production method according to the present invention provides a method for producing a porous glass body containing silicon dioxide containing at least one of a metal oxide and an anion as a main component.
Adding nitrogen to vitrify the porous glass;
In the method for producing a glass for a nitrogen-containing transparent optical component, the metal oxide or the anion is added so that the softening temperature of the glass is in a specific range.

More specifically, the present invention relates to a method for producing a porous glass body containing silicon dioxide containing at least one of a metal oxide and an anion under a nitrogen-containing reducing atmosphere. A method for producing a transparent glass for optical parts containing 0.3% by weight or more of nitrogen atoms by adding nitrogen to glass and subjecting the glass to a transparent vitrification process. However, the softening temperature of the glass is 1400 ° C. or more and 1700 ° C.
The present invention relates to a method for producing glass for optical parts, which is added as follows.

[0008] The present invention also relates to the above-mentioned manufacturing method, wherein the metal oxide is at least one of oxides of phosphorus, boron, germanium, aluminum and titanium.

[0009] The present invention also relates to the above-mentioned production method, wherein the anion is at least one of a hydroxide ion, a chloride ion and a fluorine ion.

Furthermore, the present invention provides the above-mentioned production method, wherein the porous glass body containing silicon dioxide containing at least one of the metal oxide and the anion as a main component is treated with the metal oxide. The present invention relates to a production method characterized in that at least one of a substance and an anion is obtained by a gas phase reaction.

In the above-mentioned manufacturing method, the porous glass body containing silicon dioxide as a main component containing at least one of the metal oxide and the anion may be replaced with a porous glass body containing silicon dioxide as a main component. The present invention relates to a production method characterized in that after a porous glass body is formed, a metal oxide or an anion is added to obtain the same.

Further, the present invention is the production method as described above, wherein the metal oxide is subjected to a heat treatment in an atmosphere containing a metal-containing gas to carry out a metal oxidation treatment. It relates to a production method characterized by being added.

[0013] Further, in the above-mentioned manufacturing method, it is preferable that the metal oxide is added by immersing the porous glass body in a metal-containing liquid and performing a metal oxidation treatment. .

Further, the present invention relates to the above-mentioned production method, wherein the nitrogen-containing atom-reducing atmosphere contains ammonia gas.

According to this configuration, the refractive index is increased by adding nitrogen, and the refractive index (optical characteristics) in a preferred range and the softening temperature (good workability) in a preferred range are increased by adding a metal oxide or an anion. It is possible to produce a transparent nitrogen-added quartz glass having the following.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the method for producing glass for optical parts of the present invention will be described in more detail.

The production method according to the present invention comprises: (1) a treatment of adding (2) nitrogen to a porous glass body mainly containing silicon dioxide containing at least one of a metal oxide and an anion. (3) A method for producing a glass for a transparent optical component containing nitrogen by performing a process of converting the porous glass obtained by performing the process of (2) into a transparent glass, The metal oxide or the anion in the above (1) is added in an amount in a specific range so that the softening temperature of the glass is in a specific range.

Here, the porous glass body containing silicon dioxide as a main component containing at least one of a metal oxide and an anion of (1) is a porous glass body containing silicon dioxide as a main component. (Hereinafter sometimes referred to as quartz glass or silica), which means that at least one of a metal oxide and an anion is added and contained by various known methods. Also,
As a constituent material of the porous glass, for example, synthetic quartz glass, or a material obtained by adding a viscosity adjuster or the like to synthetic quartz glass is used. This porous glass body is made of VAD
It can be manufactured by a method, an OVD method, an MCVD method, a sol-gel method, or the like. Specifically, when using VAD,
By introducing an argon gas containing silicon tetrachloride vapor into a flame formed by oxygen and hydrogen gas, a porous glass body can be obtained.

The metal oxide or anion added to the porous glass is not particularly limited, and various metal oxides or anions known to increase or decrease the refractive index of the glass may be appropriately changed. You can choose. Specific examples of the metal oxide preferably used in the present invention include oxides of phosphorus, titanium, boron, germanium, and aluminum. The anion preferably used in the present invention includes a hydroxyl ion, a chlorine ion and a fluorine ion. These can be used alone or in combination of two or more. Among such combinations, preferred combinations include phosphorus and fluorine, or titanium and fluorine. It is known that phosphorus and titanium increase the refractive index, and fluorine decreases the refractive index.
By adjusting such a combination, it is possible to lower the softening temperature and lower the viscosity without significantly changing the refractive index of the nitrogen-containing glass. In addition, the said anion in the manufactured glass is not necessarily limited to the thing contained in the ionic state, but includes the case where it is contained in the state of covalent bonding, or an intermediate state or a mixture thereof. .

These metal oxides or anions must be contained at least 0.1% by weight in order to improve the processability, and if added in a large amount, the viscosity becomes too high. % Is preferred. Within such a range, it is easy to appropriately select the type (combination) and amount of the selected metal oxide or anion so as to have a predetermined softening temperature. Further, the measurement of the amount of the metal oxide or the anion is not particularly limited, but, for example, ICP emission spectrometry can be preferably used.

Further, there is no particular limitation on the method of adding a metal oxide or an anion to the porous glass. It is possible to use the conditions of a gas phase reaction using a gas or a liquid phase reaction immersed in a solution.

Preferable examples of the addition of metal oxides or anions by a gas phase reaction include P
Cl ₃ , phosphorus oxychloride, BCl ₃ , BF ₃ , GeCl ₄ ,
Examples include AlCl ₃ , TiCl ₄ , water, chlorine gas, fluorine gas and the like. There is no particular limitation on the method of adding these metal oxides by a gas phase reaction.For example, when forming the porous glass, a gas such as phosphorus oxychloride is introduced using an inert gas such as argon. Further, it is possible to add the introduced metal by oxidizing it if necessary.

In addition, examples of those which can be preferably used when adding a metal oxide or an anion by a solution reaction include phosphoric acid, hydrochloric acid, boric acid, salts thereof, and nitrates of Ge, aluminum, and titanium. . There is no particular limitation on the method of adding these metal oxides by a solution reaction.For example, the porous glass is immersed in an aqueous solution of aluminum nitrate, dried, and then oxidized if necessary. It is possible.

The method of producing the nitrogen-containing glass used in the method of the present invention is not particularly limited, and it can be produced by using various known methods of adding nitrogen to glass containing silicon dioxide as a main component. Specifically, a predetermined amount of nitrogen atoms can be added by heating and reacting the porous glass in a reducing atmosphere containing nitrogen-containing atoms such as ammonia.

In the present invention, the amount of added nitrogen is 0.3
The content is preferably at least 0.5% by weight (more preferably at least 0.5% by weight). When the amount is less than 0.3% by weight, the characteristics of the nitrogen-containing quartz glass which is a feature of the present invention are not sufficiently exhibited. Furthermore, the upper limit of the nitrogen content is not particularly limited, and it is easy to appropriately select the nitrogen content based on the already known effect of adding nitrogen. In addition, a known analysis method can be used for the nitrogen content, and the Kjeldahl method is particularly preferable.

The nitrogen-containing quartz glass obtained by adding an appropriate amount of a metal oxide or an anion is usually porous, and there is no particular limitation on the method of making this transparent glass to obtain a transparent glass. For example, this can be achieved by heating at an appropriate temperature under an appropriate inert gas atmosphere for an appropriate time.
Examples of the inert gas include nitrogen and argon. Further, it is easy to appropriately select the heating temperature and the heating time depending on the softening temperature of each porous glass.

The transparent glass for optical parts obtained by the above-described treatment contains sufficient nitrogen and has optical characteristics showing a preferable refractive index by adding a metal oxide (or anion). Further, the softening temperature is 1400
Since it is not less than 1700C and not more than 1700C, it has good workability (especially for high-precision processing).

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

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 1 schematically shows an apparatus for producing glass used in the following embodiments. The porous glass 8 as a raw material is
It is formed on a support rod 9 which is freely inserted into and removed from the core tube 3. Alternatively, porous glass previously formed on the support rod 9 is inserted into the furnace tube 3. The furnace tube 3 is introduced into the heating furnace 12 during the processing under heating. The heating furnace 12 is heated by the heater 2.
The temperature of the heater 2 is controlled by appropriate control means. The furnace tube 3 is provided with a gas introduction path 4 and a gas discharge pipe 5. The distal end of the gas discharge pipe 5 is connected to an abatement processing device 6 for abating gas. Further, an appropriate number of branch pipes 4a to 4c for introducing various necessary gases (including a reactive gas and an inert gas) into the gas passage 4 are provided with gas supply sources 10a to 10a, respectively.
10c. If necessary, a plurality of the gas introduction passages 4 are provided in parallel with the core tube 3.

Further, metal oxides (or anions)
When the porous glass 8 is introduced by a solution reaction, the porous glass 8 is pulled out of the furnace tube 3, immersed in an appropriate solution (not shown), inserted again into the furnace tube 3, and subjected to a heat treatment. . (Example 1) First, an argon gas containing silicon tetrachloride and phosphorus oxychloride vapor was introduced into a flame of oxygen and hydrogen gas by a VAD method,
A phosphorus-containing porous silica glass body 8 having a length of 0 mm and a length of 300 mm was formed.

The porous glass body 8 is inserted into the furnace tube 3, and the inside of the furnace tube 3 is maintained in an atmosphere of a mixed gas having a 50:50 volume ratio of ammonia and nitrogen introduced from the gas introduction tube 4. The nitrogen addition treatment was performed by holding the furnace 12 at a temperature of 900 ° C. for 3 hours.

Next, the inside of the furnace tube 3 is set to a nitrogen (100%) atmosphere introduced from the gas introducing tube 4 and is maintained at a temperature of 1300 ° C. for 5 hours by the heating furnace 12 to make the porous glass body transparent vitrified. As a result, a silica glass body containing nitrogen and phosphorus was prepared.

An average softening temperature of a portion of the obtained glass was 1500 ° C. The refractive index (D line of Na) was 1.481. After stretching the obtained glass body in a heating furnace to a diameter of 20 mm, VA was again applied.
According to Method D, an argon gas containing silicon tetrachloride vapor was introduced into a flame formed by oxygen and hydrogen gas, and glass fine particles were deposited around the stretched body. The obtained glass stretched body porous glass composite was inserted into a heating furnace, and the inside of the furnace was
% Helium atmosphere, and kept at 1450 ° C. for 3 hours to form an integrated and transparent glass.

From the obtained glass body, the following glass fiber was heated to 1850 ° C. in a heating furnace (not shown), and spin-coated to an outer diameter of 125 μm, and an ultraviolet-curable resin was applied and cured to form an outer diameter of 250 μm. An optical fiber was obtained.

When the transmission loss at a wavelength of 850 μm was measured for the obtained optical fiber 500 m, 7.6 was obtained.
It was dB / km. (Example 2) First, an argon gas containing silicon tetrachloride vapor was introduced into a flame formed by oxygen and hydrogen gases,
A porous silica glass body 8 having a diameter of 80 mm and a length of 300 mm was formed on the support rod 9 by the VAD method.

The obtained porous glass body 9 is inserted into the furnace core tube 3, and a mixed gas having a volume ratio of boron trifluoride and helium of 20:80 is introduced from the gas introduction tube 4 through the furnace core tube 3. After maintaining the temperature in the heating furnace 12 at a temperature of 1000 ° C. for 1 hour, the gas atmosphere in the furnace tube 3 is changed by introducing a mixed gas having a volume ratio of oxygen and helium of 20:80 from the gas introduction tube 4, It was kept for another 2 hours. Next, ammonia and nitrogen are passed through the furnace core tube 3 from the gas introduction tube 4 in a volume ratio of 50:
A mixed gas of 50 was introduced, and a nitrogen addition treatment was performed while maintaining the atmosphere at 950 ° C. for 3 hours.

Thereafter, the inside of the furnace tube 3 is made into a nitrogen atmosphere (100%) by a gas introducing tube 4, kept at a temperature of 1350 ° C. for 5 hours, and the porous glass body 8 is turned into a transparent glass to obtain A boron-containing silica glass body was prepared. A portion of the obtained glass was measured for an average softening temperature, which was 1490 ° C. The refractive index is 1.
465.

The obtained glass body was further heated to a diameter of 2
After stretching to 0 mm, a quartz glass layer was formed again by the VAD method so as to have an outer diameter of 50 mm around the stretched body.

From the obtained glass body, the following glass fiber was heated to 1950 ° C. in a heating furnace (not shown) and spun to an outer diameter of 125 μm, and an ultraviolet curing resin was applied and cured. An optical fiber having an outer diameter of 250 μm was obtained.

When the transmission loss at a wavelength of 850 μm was measured for the obtained optical fiber 500 m, 8 dB was obtained.
/ Km. (Example 3) First, an argon gas containing silicon tetrachloride vapor was introduced into a flame formed by oxygen and hydrogen gases,
A porous silica glass body 8 having a diameter of 80 mm and a length of 300 mm was formed on a support rod 9 by the VAD method.

The resultant porous glass body 8 of aluminum nitrate _{(Al (NO 3) 3 9H} 2 O) aqueous solution (aluminum weight 3
%) (Not shown). Next, the obtained porous glass body is kept in a dry nitrogen gas stream, and after sufficiently evaporating water as a solvent, the porous glass body is inserted into the furnace core tube 3, oxygen gas is introduced from the gas introduction tube 4, and oxygen is introduced into the atmosphere. Then, the oxidation treatment was performed while maintaining the heating furnace 12 at 800 ° C. for 1 hour.

Next, a mixed gas of ammonia and nitrogen in a volume ratio of 50:50 is introduced into the furnace core tube 3 from the gas introducing tube 4 through the gas introducing tube 4 to maintain the atmosphere.
For 3 hours to perform a nitrogen addition treatment. Thereafter, nitrogen gas (100%) is introduced into the furnace core tube 3 from the gas introduction tube 4 to form a nitrogen atmosphere.
The porous glass body was kept transparent at 5 ° C. for 5 hours to produce a silica glass containing nitrogen and aluminum. A portion of the obtained glass was measured for an average softening temperature, which was 1660 ° C. The refractive index is 1.
487.

After the obtained glass body was further heated and stretched to a diameter of 20 mm, a quartz glass layer was formed again by the VAD method so as to have an outer diameter of 50 mm around the stretched body.

The obtained glass body was heated to 2050 ° C. in a heating furnace (not shown) and spun to an outer diameter of 125 μm.
An ultraviolet curable resin was applied and cured to obtain an optical fiber having an outer diameter of 250 μm.

The transmission loss at a wavelength of 850 μm was measured for the obtained optical fiber 500 m.
It was dB / km. (Comparative Example) Under the same conditions as in Example 1, after forming a porous silica glass without adding phosphorus, a nitrogen addition treatment was performed in a heating furnace, and the mixture was kept at 1450 ° C. for 4 hours. A transparent vitrification treatment was performed. Two of these were created. One of them was white and contained about 1.2% by weight of nitrogen in the glass, but could not be made vitrified.

The other one contained about 1.1% by weight of nitrogen and was vitrified, but its softening temperature was 17%.
40 ° C. Further, the viscosity at high temperatures is very high, and the processing temperature is set to about 150 in various processing steps as compared with Example 1.
℃ or more, especially in the drawing process,
It could not be heated and melted sufficiently in the drawing furnace, and an optical fiber could not be obtained.

[0047]

According to the constitution of the present invention, the refractive index is increased by adding nitrogen, and the refractive index (optical characteristics) in a preferred range and the softening temperature (good) in a preferred range are increased by adding a metal oxide or an anion. (Processability) can be produced. In other words, the refractive index is increased by adding nitrogen to quartz glass, and this is a more economical manufacturing method than a known method in which germanium or the like is added. Further, by adding a metal oxide or an anion, the softening temperature is lowered, the workability is improved, the molding process is facilitated, and the equipment is simplified and economical. Further, the lowering of the softening temperature prevents foaming due to desorption of nitrogen, and facilitates obtaining a transparent glass.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a manufacturing apparatus to which a glass manufacturing method for an optical component of the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 3 ... Core tube, 4 ... Gas introduction path, 4a ... Branch tube, 4b ... Branch tube, 4c ... Branch tube, 5 ... Gas discharge tube, 6 ... Abatement processing device, 8 ... Porous glass, 9 ... Support rod, 10a: gas supply source, 10b: gas supply source, 10c: gas supply source, 12 ...
heating furnace

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadashi Enomoto 1 Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Yama ▲ saki ▼ Taku 1 Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Address F-term in Sumitomo Electric Industries, Ltd. Yokohama Works 4G014 AH02 4G021 BA00

Claims (8)

[Claims] 1. A porous glass body mainly containing silicon dioxide containing at least one of a metal oxide and an anion, to which nitrogen is added in a nitrogen-containing atom-reducing atmosphere to form the porous glass. In the method for producing a transparent glass for optical parts containing 0.3% by weight or more of nitrogen atoms by vitrification, the metal oxide or the anion may have a softening temperature of 1400 ° C. to 1700 ° C.
A method for producing glass for optical parts, characterized by being added as follows. 2. The manufacturing method according to claim 1, wherein the metal oxide is at least one of oxides of phosphorus, boron, germanium, aluminum, and titanium. 3. The production method according to claim 1, wherein the anion is at least one of a hydroxyl ion, a chloride ion, and a fluorine ion. 4. The production method according to claim 1, wherein the porous glass is composed mainly of silicon dioxide containing at least one of the metal oxide and the anion. A method for producing a body by adding at least one of the metal oxide and the anion by a gas phase reaction. 5. The production method according to claim 1, wherein the porous glass body contains silicon dioxide containing at least one of the metal oxide and the anion as a main component. After forming a porous glass body containing silicon dioxide as a main component, adding a metal oxide or an anion. 6. The production method according to claim 5, wherein the metal oxide is added by subjecting the porous glass body to a heat treatment in an atmosphere containing a metal-containing gas and performing a metal oxidation treatment. A manufacturing method characterized by: 7. The method according to claim 5, wherein the metal oxide is added by immersing the porous glass body in a metal-containing liquid and performing a metal oxidation treatment. Production method. 8. The manufacturing method according to claim 1, wherein said nitrogen-containing atom reducing atmosphere contains ammonia gas.