JP2000319024A - Apparatus for production of porous glass preform and production of porous glass preform using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing a porous glass preform which has a clean reaction chamber and a process for producing the porous glass preform with which the generation of air bubbles and the inclusion of foreign matter are lessened by using the apparatus. SOLUTION: This process for producing the porous glass preform 4 includes a chamber 1, the reaction chamber 5 which is installed in the chamber, blows glass raw material and reactive gas to the surface of a starting member 3 by an oxyhydrogen burner and forms the porous glass preform by depositing glass particulates on the surface, a discharge pipe 6 for discharging the by- produced gases generated in the reaction chamber and a suction port 7 for feeding the outdoor air into the chamber. A filter 8 is mounted at the suction port and the spacing in the chamber is sealed. This process for producing the porous glass preform produces the porous glass preform by using the apparatus for production described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a porous glass base material and a method for manufacturing a porous glass base material using the same, and more particularly to a method for manufacturing a porous glass base material. The present invention relates to a manufacturing apparatus and a manufacturing method capable of preventing contamination, generation of bubbles, and the like.

[0002]

2. Description of the Related Art Conventionally, the production of a porous glass preform has
In an oxyhydrogen flame burned in the presence of oxygen and hydrogen, tetrachlorosilane or tetrachlorogermanium undergoes a hydrolysis reaction in a gas phase to generate glass particles, and the generated glass particles are deposited on a starting member to form a porous body. While producing a high-quality glass base material, glass fine particles and by-product gas not deposited on the starting member are exhausted outside the chamber through an exhaust pipe, and new outside air is sent into the chamber through an intake pipe. I have.

As described above, when the outside air is introduced into the chamber through the intake pipe, it is necessary to feed the same amount of gas exhausted from the chamber into the chamber. in this case,
Since outside air is taken into the chamber from the outside of the reactor as it is, dust and foreign matter (particles) floating in the outside air are entrained. Therefore, foreign substances and the like taken in together with the outside air adhere to the surface of the porous glass base material being manufactured, and this is one of the factors that cause defective products in which bubbles or foreign substances are taken in in the subsequent vitrification process. Had one.

Therefore, as means for solving such a problem, the position of the exhaust pipe and the shape of the exhaust hood have been improved in order to improve the exhaust efficiency of the reaction chamber (JP-A-59-19023).
No. 2, JP-A-1-208338), a filter is attached to the intake port for sending clean outside air into the chamber (see JP-A-60-210540), or a burner flame area, gas amount, or the like. The displacement is adjusted according to the growth of the base material (JP-A-5-155630, JP-A-6-234439, JP-A-9-124).
No. 334) has been proposed.

[0005]

However, even if any of the above methods is carried out, a turbulence occurs in the gas flow between the gas exhausted in the reactor and the supplied outside air, so that the glass particles become porous. The non-adhered glass particles are aggregated in a state where they are not adhered to the surface of the glass base material, or the unadhered glass particles accumulate in the place where the air flow is stagnant in the reactor, and these unadhered glass particles are completely removed from the reactor. Could not be discharged to For this reason, when these non-adhered glass particles adhere to the surface of the porous glass base material, they cause air bubbles in the subsequent vitrification step.

Further, since the porous glass base material is produced by the gas phase hydrolysis reaction as described above, a large amount of corrosive hydrogen chloride gas is by-produced. For this reason, if the reactor is used for a long time, not only the reaction chamber but also the site where the metal is used in the reactor is corroded, and foreign substances such as rust are easily generated. Then, the generated particles flow into the reaction chamber and adhere to the porous glass base material being manufactured, causing the generation of air bubbles and the mixing of foreign substances. As described above, the conventional problem that bubbles are generated in the porous glass base material and foreign matters are mixed has not been completely solved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an apparatus for producing a porous glass base material having a clean reaction chamber and the use of the apparatus reduce generation of bubbles and entry of foreign matter. It is an object of the present invention to provide a method for producing a porous glass base material.

[0008]

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and the invention described in claim 1 of the present invention comprises a chamber, and is provided in the chamber.
A reaction chamber for forming a porous glass base material by ejecting a glass raw material gas from an oxyhydrogen burner, causing a gas phase hydrolysis reaction in an oxyhydrogen flame to deposit glass particles on the surface of the starting member. An exhaust pipe for exhausting a by-product gas generated in the reaction chamber, and an intake port for sending outside air into the chamber; An apparatus for producing a porous glass base material, wherein the apparatus is mounted and a gap in the chamber is sealed.

As described above, if the filter is attached to the intake port of the manufacturing apparatus of the porous glass base material and the gap in the chamber is sealed, dust and foreign matter in the outside air sent into the chamber can be removed, so that the cleaning is performed. In addition to taking in outside air, it is possible to avoid inhaling outside air from places other than the intake port. Therefore, since the reaction chamber can be kept in a clean state, if the porous glass base material is manufactured using the present apparatus, the contamination of the product from the atmosphere can be reduced.

According to a second aspect of the present invention, a chamber and a glass source gas installed in the chamber are blown out from an oxyhydrogen burner to cause a gas phase hydrolysis reaction in an oxyhydrogen flame. A reaction chamber for depositing glass microparticles on the surface of the starting member to form a porous glass preform, an exhaust pipe for exhausting by-product gas generated in the reaction chamber, and sending outside air into the chamber An apparatus for manufacturing a porous glass base material having a suction port for mounting a filter on the suction port and disposing the exhaust pipe in a portion other than the reaction chamber in the chamber. This is an apparatus for manufacturing a high quality glass base material.

As described above, if the filter is attached to the intake port of the apparatus for manufacturing a porous glass base material and the exhaust pipe is disposed in a portion other than the reaction chamber, clean outside air can be taken into the chamber as described above. At the same time, it is also possible to exhaust gas at a place other than the reaction chamber, so that it is possible to remove foreign matter and the like generated from components of the apparatus other than the reaction chamber. Accordingly, the reaction chamber can be kept in a clean state, as in the above, so that contamination of the product can be reduced even when the present apparatus is used to manufacture a porous glass base material.

Further, according to the third aspect of the present invention, a chamber and a glass source gas installed in the chamber are blown out from an oxyhydrogen burner to cause a gas phase hydrolysis reaction in an oxyhydrogen flame. A reaction chamber for depositing glass microparticles on the surface of the starting member to form a porous glass preform, an exhaust pipe for exhausting by-product gas generated in the reaction chamber, and sending outside air into the chamber A porous glass preform manufacturing apparatus having a suction port for attaching a filter to the suction port, sealing a gap in the chamber, and connecting the exhaust pipe to a portion other than the reaction chamber in the chamber. An apparatus for manufacturing a porous glass base material, wherein the apparatus is also arranged.

As described above, if the filter is attached to the intake port of the apparatus for manufacturing a porous glass base material, the gap in the chamber is sealed, and the exhaust pipe is disposed in a position other than the reaction chamber, the gas is sent into the chamber. Since dust and foreign matter in the outside air can be removed, the effect of taking in clean outside air, cutting off contact with outside air in places other than the intake port, and removing foreign matters from dust sources located in places other than the reaction chamber can be achieved. Obtained at the same time. Therefore, since a reaction chamber with a higher degree of cleanliness can be obtained, if a porous glass base material is manufactured using this apparatus,
It is possible to manufacture a base material with almost no foreign substances mixed therein.

In this case, as described in claim 4, the multiple
Of the atmosphere in the reaction chamber during the production of porous glass preform
Leanness less than class 1000 is preferred
No. Thus, the reaction during the production of the porous glass preform is
Cleanliness of the atmosphere in the room is less than 1000 class
If the production equipment has a reaction chamber with extremely high cleanliness,
Can be Note that the cleanliness level is less than class 1000.
Full means that particles of 0.5 μm or more are 1 ft ^Three 100 per
It means that the number is less than 0.

[0015] Such claims 1 to 4 are as follows.
By manufacturing the porous glass base material using the manufacturing apparatus according to any one of the claims, a porous glass base material having uniform quality and reduced generation of bubbles and foreign matter is manufactured. (Claim 5). Further, if glass particles are deposited in an atmosphere having a cleanness of less than 1000 in the reaction chamber, a porous glass base material free of bubbles and foreign substances can be reliably produced (claim 6).

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. In order to obtain a porous glass base material with reduced generation of air bubbles and foreign substances, it is essential to manufacture the porous glass base material in a clean manufacturing equipment. The inventors of the present invention have conceived that it is only necessary to improve the intake port and exhaust efficiency of the apparatus and to cut off the contact with the outside air, and have completed the present invention.

Hereinafter, an apparatus for manufacturing a porous glass base material according to the present invention will be described with reference to FIG. FIG. 1 shows an example in which the apparatus for manufacturing a porous glass base material of the present invention is applied to an apparatus based on an OVD method (external CVD method). In this manufacturing apparatus, a glass raw material gas is jetted from an oxyhydrogen burner 2 and a gas phase hydrolysis reaction is performed in an oxyhydrogen flame to deposit glass fine particles generated on the surface of the starting member 3. A reaction chamber 5 for forming a porous glass preform 4 by
A conventional porous glass preform manufacturing apparatus is provided with an exhaust pipe 6 for exhausting by-product gas generated in the reaction chamber 5 and an intake port 7 for sending outside air into the chamber 1. The same is true.

A feature of the apparatus for manufacturing a porous glass base material of the present invention is that a filter 8 (hatched portion) is attached to the intake port 7,
The point is that a gap in the chamber 1 is sealed to be a sealed type, and exhaust pipes 9 and 10 are arranged in addition to the reaction chamber 5. Further, these exhaust pipes are provided with a control valve 11 for adjusting the displacement.

As described above, by attaching the filter 8 to the intake port 7, dust and foreign matters floating in the outside air can be removed, and clean outside air can be sent into the chamber 1. As this filter 8, HEPA (H
high Efficiency Particulate
Air) filter and ULPA (Ultra LowP)
Entration Air) filter and the like.
Those capable of removing particles having the following sizes by 90% or more are preferable. The opening area of the outside air intake can be determined from the filtration linear velocity specification of the attached filter and the air volume at the time of intake.

Further, in the present invention, a gap in the chamber 1 can be sealed in order to block contact or suction with outside air other than the intake pipe 7 which is an outside air intake.
By the way, a reaction apparatus is usually composed of a reaction chamber, a drive system for rotation and traverse, piping for supplying raw materials and fuel gas, valves, an exhaust pipe, and the like. A method of feeding outside air to the reaction chamber as a configuration in which the intake path is isolated from the device components,
There is a method in which the components of the device are integrated, the outside is covered with a panel or the like, and an outside air intake is provided in this panel.

In any case, if there is a gap directly in contact with the outside air in the path leading to the outside air into the reaction chamber 5,
Outside air enters the reaction chamber 5 without passing through the filter 8. Therefore, there is a possibility that foreign matter or particles contained in the outside air may adhere to the surface of the porous glass base material 4, and the gap in the chamber 1 is sealed to avoid this. As a method of sealing, for example, when a panel or the like is installed, a method of sandwiching a packing or the like between the panel and the mounting frame, or closing the space between the panels with a sealing material is exemplified. In this case, a room temperature curing type silicone rubber or the like can be used as the sealing material.

As described above, when the filter 8 is attached to the intake port 7 and the gap in the chamber 1 is sealed, only the clean outside air from which dust and foreign matters floating in the outside air have been removed is introduced into the chamber 1. Can be sent in and the inlet 7
It is possible to cut off contact or inhalation with the outside air at other times. Therefore, by using this apparatus, it is possible to manufacture the porous glass base material 4 in which generation of bubbles and entry of foreign matter are reduced.

The inventors of the present invention have conducted intensive studies to produce a high-quality product with a lower contamination level. As a result, components other than the reaction chamber 5 in the chamber 1 have a dust source, for example, rust generated from metal parts. If any of the above is present, foreign substances and particles generated from these dust sources enter the reaction chamber 5 and are found to be one of the sources of product contamination. Therefore,
It is considered that if such contamination can be avoided, it is possible to manufacture the porous glass base material 4 with almost no generation of bubbles and no foreign matter mixed therein. We found that it was only necessary to install a pipe to improve exhaust efficiency.

Other than the reaction chamber 5, an exhaust pipe may be installed at a place where dust may be generated, for example, a burner, a drive system for rotation or traverse, a pipe for supplying a raw material or fuel gas, valves and the like. , Exhaust pipes and the like. In order to pipe the exhaust pipe to each location, the pipe for exhausting from the reaction chamber 5 may be branched by the number of places where the exhaust is desired, or may be independent pipes. Further, the exhaust volume of each exhaust pipe cannot be specified unconditionally because it differs depending on the scale of the manufacturing apparatus. For example, the exhaust from the reaction chamber is 10 Nm ³ / min, and the exhaust from the room containing the exhaust pipe is 1 Nm ^3. / Min, exhaust air from the room containing the burner drive system, gas piping, etc. by 1 Nm ³
/ Min condition.

As described above, if an exhaust pipe is provided in the manufacturing apparatus in addition to the reaction chamber 5 and the filter 8 is attached to the intake port 7, clean outside air can be sent into the chamber 1 and the reaction chamber can be supplied. It is possible to prevent dust generated from components other than 5 from entering the reaction chamber 5. Furthermore, it is possible to prevent an airflow from flowing into the reaction chamber 5 at an opening connecting portions other than the reaction chamber 5 in the chamber 1. Therefore, it is possible to manufacture the porous glass base material 4 in which generation of bubbles and entry of foreign matter are reduced.

Further, when it is desired to produce a high-quality porous glass base material, the components of the reactor are integrated and
After covering the outside with a panel, etc.,
Is provided, the space between the panels is sealed, and a place other than the reaction chamber 5, for example, near a burner or a driving system, a place where exhaust pipes are assembled (9 and 10 in FIG. 1), etc. It is desirable to install an exhaust pipe.

In this case, the cleanliness of the atmosphere in the reaction chamber 5 at the time of manufacturing the porous glass base material 4 is set to class 100.
Reaction chamber 5 which can be less than 0 and has extremely high cleanliness
It can be. The degree of cleanness in the reaction chamber 5 can be controlled by class 100 by adjusting the type of filter, exhaust conditions, and the like.
The porous glass preform produced by this device can be of very high quality.

As described above, in the method for manufacturing the porous glass preform 4 using the apparatus for manufacturing a porous glass preform according to the present invention, during the manufacturing, the outside air is supplied to the chamber 1 through the filter 8.
In addition to avoiding contact with the outside air that does not pass through the filter 8, the exhaust pipes 9 and 10 are disposed in addition to the reaction chamber 5 so that the exhaust is performed. A high quality porous glass preform 4 is obtained.

[0029]

The present invention will be described below with reference to examples and comparative examples.

Example 1 A porous glass preform was manufactured as follows using an apparatus for manufacturing a porous glass preform by the OVD method as shown in FIG. From a burner arranged in this apparatus, silicon tetrachloride as a glass source gas and oxygen and hydrogen as reaction gases are supplied, glass fine particles are generated by a gas phase hydrolysis reaction, and glass fine particles are deposited on a starting member. Thus, ten soot-like porous glass preforms 4 of about 40 kg were prepared, and numbers 1 to 10 were given to each of them.

[0031] At this time, at 10 Nm ³ / min condition exhaust for exhausting the reaction chamber 5, the exhaust from the room to the exhaust pipe or the like is housed in 1 Nm ³ / min of conditions, the burner drive system, 1 Nm of exhaust gas from the room where gas pipes are stored
^The gas was exhausted through the exhaust pipes 6, 9 and 10 under the condition of ³ / min. The total amount of exhaust (12 Nm ³ / min) exhausted through the three exhaust pipes was taken into the chamber 1 through the HEPA filter 8. All the gaps of the panel attached to the outside of the reactor were sealed with silicone sealant KE45 (manufactured by Shin-Etsu Chemical Co., Ltd.) so that outside air was not taken in from places other than the filter.

During the production, the reaction chamber 5 shown in FIG.
When the number of particles at the location indicated by the symbol x was measured using a particle counter, the number of particles of 0.5 μm or less per 1 ft ³ was 20 on average. Next, a vitrification process was performed, and when the number of bubbles in the obtained transparent vitrified optical fiber preform was counted, it was about 31 on average. The results are shown in Table 1.

[0033]

[Table 1]

(Embodiment 2) The same conditions as in Embodiment 1 except that the exhaust from the room containing the exhaust pipe 10 and the like and the exhaust 9 from the room containing the burner drive system, gas piping, etc. were not performed. , Four porous glass preforms 4 of about 40 kg were produced, and numbers 1 to 4 were given to each of them. During the production, the number of particles at the location indicated by the mark x in the reaction chamber shown in FIG. 1 was 28 on average. Next, a vitrification process was performed, and when the number of bubbles in the obtained transparent vitrified optical fiber preform was counted, it was about 57 on average. The results are shown in Table 2.

[0035]

[Table 2]

(Comparative Example) The exhaust from the room containing the exhaust pipe 10 and the like and the exhaust 9 from the room containing the burner drive system, gas piping, etc. were not performed, and instead of the HEPA filter 8, a polyester felt was used. Approximately 40k under the same conditions as in Example 1 except that the filter for coarse dust was used and the reactor was not sealed with a silicone sealant.
g of porous glass preform 4 were prepared, and 1
Numbers from 10 to 10 were given. During the production, the number of particles at the location indicated by the cross in the reaction chamber shown in FIG. 1 was 1100 on average. Next, a vitrification process was performed, and when the number of bubbles in the obtained transparent vitrified optical fiber preform was counted, it was about 142 on average. Table 3 shows the results.
It was shown to.

[0037]

[Table 3]

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the claims of the present invention. Within the technical scope of

For example, in the above-described embodiment, an example is shown in which the present invention is applied to an apparatus for manufacturing a porous glass base material by the OVD method. However, the present invention is not limited to this.
The same effect can be obtained even when applied to the AD method, the MCVD method, or another manufacturing method.

[0040]

According to the present invention, if a porous glass preform is manufactured using the apparatus for manufacturing a porous glass preform having a clean reaction chamber according to the present invention, generation of air bubbles and foreign matter can be achieved without making the whole room a clean room. Can be easily and inexpensively manufactured with a porous glass base material in which contamination of the glass is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one example of an apparatus for producing a porous glass base material of the present invention.

[Explanation of symbols]

1 ... chamber, 2 ... burner, 3 ... starting member,
4 ... porous glass base material, 5 ... reaction chamber, 6 ... exhaust pipe, 7 ... intake port, 8 ... filter, 9 ... exhaust pipe, 10 ... exhaust pipe , 11 ... control valve, x ... particle count measurement place.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaya Ueno 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Kagaku Kogyo Co., Ltd. Precision Functional Materials Laboratory (72) Inventor Yuji Tobisaka Annaka, Gunma 2-13-1, Isobe-shi, Shin-Etsu Kagaku Kogyo Co., Ltd.Precision Functional Materials Research Laboratory (72) Inventor Tadakatsu Shimada 2-3-1-1, Isobe, Annaka-shi, Gunma Prefecture Shin-Etsu Kagaku Kogyo Co., Ltd. 72) Inventor Hideo Hirasawa 2-13-1 Isobe, Annaka-shi, Gunma F-term in Shin-Etsu Chemical Co., Ltd. Precision Functional Materials Laboratory 4G014 AH14 AH23 4G021 EA03 EB18

Claims (6)

[Claims] Claims: 1. A chamber and a glass source gas installed in the chamber. The glass source gas is jetted from an oxyhydrogen burner, and a gas phase hydrolysis reaction is performed in an oxyhydrogen flame to deposit glass particles on the surface of the starting member. A reaction chamber for forming a porous glass base material, an exhaust pipe for exhausting by-product gas generated in the reaction chamber, and a suction port for sending outside air into the chamber. An apparatus for manufacturing a porous glass base material, wherein a filter is attached to the intake port and a gap in the chamber is sealed. 2. A chamber and a glass source gas installed in the chamber, wherein a glass source gas is jetted from an oxyhydrogen burner, and a gas phase hydrolysis reaction is performed in an oxyhydrogen flame to deposit glass fine particles on the surface of the starting member. A reaction chamber for forming a porous glass base material, an exhaust pipe for exhausting by-product gas generated in the reaction chamber, and a suction port for sending outside air into the chamber. An apparatus for manufacturing a porous glass preform, wherein a filter is attached to the intake port and the exhaust pipe is arranged in a portion other than the reaction chamber in the chamber. 3. A chamber and a glass source gas installed in the chamber. The glass source gas is jetted from an oxyhydrogen burner, and a gas phase hydrolysis reaction is performed in an oxyhydrogen flame to deposit glass particles on the surface of the starting member. A reaction chamber for forming a porous glass base material, an exhaust pipe for exhausting by-product gas generated in the reaction chamber, and a suction port for sending outside air into the chamber. In the apparatus for manufacturing a base glass base material, a filter is attached to the intake port, a gap in the chamber is sealed, and the exhaust pipe is disposed in a portion other than the reaction chamber in the chamber. Equipment for manufacturing porous glass base material. 4. The method according to claim 1, wherein the degree of cleanness of the atmosphere in the reaction chamber during the production of the porous glass base material is less than 1,000.
An apparatus for producing a porous glass base material according to the above item. 5. A method for manufacturing a porous glass base material, comprising manufacturing a porous glass base material using the manufacturing apparatus according to claim 1. 6. A glass raw material gas is spouted from an oxyhydrogen burner in a reaction chamber, and a gas phase hydrolysis reaction is performed in an oxyhydrogen flame to deposit glass fine particles on the surface of the starting member to form a porous glass mother. A method for producing a porous glass base material, comprising: depositing glass fine particles with a cleanness of an atmosphere in a reaction chamber at the time of producing the porous glass base material being less than class 1000.