JPH02157132A - Production of high-purity quatrz glass - Google Patents

Abstract

PURPOSE:To increase the transmissivity of the subject glass and to eliminate the 2,730nm absorption based on the OH stretching vibration by allowing the porous base material obtained by depositing fine SiO2 particles to react with a chlorinating agent, then removing the residual chlorinating agent and vitrifying the material. CONSTITUTION:Silicon halide (e.g. SiCl4) is hydrolyzed in a flame under the conditions where the flow rate ratio of H2 to O2 is controlled to 0.5-2.0 and that of H2 to silicon halide to 10-100, and the obtained fine SiO2 particles are deposited to obtain a porous base material. The base material is then allowed to react with a chlorinating agent (e.g. Cl2) at 1,000-1,300 deg.C. The reaction product is dehydrated, then heated at 1,000-1,300 deg.C to remove the residual chlorinating agent, and vitirfied at 1,450-1,550 deg.C. Consequently, the high-purity quartz glass having >=88% transmissivity in the 200-2,500nm wavelength region and without the 2,730nm absorption based on the OH stretching vibration is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing high-purity quartz glass, and particularly to a method for manufacturing high-purity quartz glass, which has a transmittance of 88% or more over a wide wavelength range of 200 nm to 2,500 nm, and Based on stretching vibration 2
．． This relates to the production capacity of high-purity quartz glass with no absorption at 730 nm. High-purity quartz glass is widely used in scientific instruments, lighting tubes, furnace tubes for kermanium and silicon semiconductor manufacturing, and optical crystals. It is also expected to be used as a high-performance abrasive material in advanced science and technology industries such as the electronics industry, optical industry, and space industry, taking advantage of the characteristics of high-purity quartz glass.

[Conventional technology]

Conventionally, a known method for obtaining quartz glass is the Bertai method, in which natural quartz powder is used as a raw material and melted in an oxyhydrogen flame. The fused silica glass obtained by this method is mainly used for semiconductors, but since natural crystal powder is used as a raw material, it is difficult to achieve high purity. When using quartz glass as the optical cable 4A, impurities contained in the glass affect the ultraviolet transmittance. Furthermore, since melting is performed using an oxyhydrogen flame, 011 groups are contained in the glass. 1 liter of O in the glass
The presence of such groups causes absorption at 2,730 nm due to 011 stretching vibration when used as an optical moon, and has the disadvantage of poor heat resistance when used as a semiconductor device.

Instead of using an oxyhydrogen flame, a method is also known in which natural crystal powder is heated and melted using electric heat such as high-air resistance and high-frequency waves. The so-called electrical products obtained by this method contain 011 groups in the glass and are used for semiconductors because they have good heat resistance.
Furthermore, since it does not absorb absorption at 2.730 nm due to 011 stretching vibration, it is also used as a glass for infrared transmission. However, since the most important product is made from natural quartz powder, like fused silica glass, it has low purity and poor ultraviolet transmittance, so it is not used for ultraviolet optical applications.

A known method for obtaining quartz glass with high purity and good ultraviolet transmittance is to use S + Cl4 as a raw material, hydrolyze it with an oxyhydrogen flame, and then grind the quartz glass.

Synthetic quartz glass produced by this method can use S + C14, which can be purified, as a raw material, so high-purity quartz glass can be obtained and the ultraviolet transmittance is good, but oxyhydrogen flame is used for synthesis. 2,730, which contains a large amount of 011 group in the glass and is based on OH stretching vibration.
It produces absorption in the nm range, so it cannot be used as an infrared transmitting glass.

A method for preparing quartz (quartz) with good ultraviolet transmittance but no absorption at 2.730 nm is S i Cl 4
Is there a way to make synthetic quartz glass by thermal oxidation reaction using plasma heating? This method requires complicated equipment and requires a lot of synthesis time. Synthetic silica glass with a yield of +1' or low i' is highly curved.

Therefore, synthetic quartz glass is usually used for ultraviolet transmission, and fused glass is used for infrared transmission, respectively.

On the other hand, as a method for obtaining quartz glass other than the above-mentioned method, the VAD method, which is a method for manufacturing a single-shaft for optical fiber, is known. The VAD method is to hydrolyze silicon halide in an oxyhydrogen flame to form S + 02 fine particles, and the Si
In this method, after depositing 02 fine particles to form a porous preform, the porous preform is dehydrated and vitrified to obtain a preform for optical fibers. The feature of this method is that dehydration treatment is performed using a chlorinating agent in order to reduce the absorption loss of leaf base stretching vibration, which is a problem in optical fibers.
Items with no absorption at 0 nm are shown in 111.

JP-A No. 54-103038 describes an anhydrous silica glass motherboard for optical fibers that does not contain Oll by replacing the 011 story with C1 using 5oc12. 11 methods are described.

But VAD? The quartz glass obtained with , l is
Since it is intended to be used as an optical fiber, additives such as Gc are added to form a refractive index distribution, reducing the purity. Emphasis was placed on transmittance, and ultraviolet transmittance, which is a characteristic of silica glass, was unknown.

JP-A-58-1.7 [1134] describes a method of heat-treating a porous stone in a gas atmosphere containing a chlorinating agent to obtain transparent vitrification. This method was carried out to increase the degree of modification of the optical fiber, and based on the stretching vibration of the 011 group, no absorption occurred at <2,730 nm or the ultraviolet transmittance was unknown. Also, Japanese Patent Publication No. 5413412
Publication No. 8 discloses that a porous base material is set above a heating furnace with a dehydration treatment area and a transparent vitrification area connected vertically, and is gradually lowered without rotating, and heated to 400°C in the dehydration treatment area.
Heating to ~500°C, dehydration treatment is carried out by feeding CCl415 together with Ilc gas, and then vitrification is carried out using Ilc gas.
A method is described in which the vitrification is carried out in an inert gas such as . When this method is used as an optical fiber, 012 remains in the glass and the wavelength ranges from 700 nm to 1. l
This was done to prevent absorption loss from occurring at wavelengths of 700 nm to 1.0 nm, and it was unclear whether a glass with no absorption loss at wavelengths of 700 nm to 1.0 nm was obtained or not, and its ultraviolet transmittance was unknown.

When the present inventors carried out vitrification in an inert gas continuously after dehydration treatment in a two-stage method in a chlorinating agent-containing gas atmosphere or in a continuous method, they found that
The quartz glass, which had no absorption at 2.730 nm, was exposed to 11 J or often exhibited absorption in the ultraviolet wavelength range of 240 nm to 280 nm.

As mentioned above, in the conventional method, wavelengths from 200 nm to 2
．． Is it easy to produce high-purity quartz glass that has a transmittance of 88% or more in a wide wavelength range of 500nm+ and does not absorb <2,730nm based on 011 stretching vibration? It was difficult to get the first result.

[Invention or problem to be solved]

The L1 target of the present invention is from wavelength 200 nm to 2,500 nm.
Transmittance of 88% or more in a wide wavelength range of nm and 0
The purpose of the present invention is to provide a method for easily manufacturing high-purity quartz glass, which is based on stretching vibrations and has no absorption at <2,730 nm, without using complicated equipment.

[Means to solve the problem]

As a result of various studies conducted by the present inventors in order to suppress the absorption of ultraviolet light, we found that after dehydration treatment with a chlorinating agent, the chlorinating agent remaining in the porous material was By removing with vitrification atmosphere gas, wavelength 200 old 1
] to 2.50 On +n, the transmittance is 88% or more in a wide wavelength range, and based on the 011 stretching vibration < 2.
Pure quartz glass with no absorption at 730nm? I found out that.

The gist of the present invention is to hydrolyze halogenated silicon in a flame to form 5in2 fine particles, deposit the S jo 2 fine particles to form a porous matrix, and then chlorinate the porous matrix. In the method of obtaining quartz glass by reacting it with a dehydrating agent and then vitrifying it, the chlorinating agent remaining in the porous matrix is removed using a vitrification atmosphere gas before vitrification. The method of manufacturing high-purity quartz glass is described in detail below.

The raw material silicon halide used in the present invention includes S i Cl, S r If Cl 3, etc., but 5IC14 is generally used.

The burner for synthesizing porous nitrogen is not particularly limited, but a quartz concentric multiple shield burner or a quartz square multi-tube burner shade can be used. iH: ; i
In order to synthesize at high speed, it is necessary to use a plurality of burners or a large number of multiplexed tubes, and the gas flow rate used changes depending on the structure of these burners and the synthesis method.

The gas used is not particularly limited, and H2 gas, 02 gas, and Ar gas can be used. The flow rate of these dregs to be used is based on the flame/IL IU + burner~+1111 structure and the number of used -・n, and the gas flow rate from the 6 shields is optimized. The composite material is wrapped in a porous material. The flow=ratio of commonly used H,02 and H,,5il1
The four flow rate ratios are each H2102=f1.5-2.0.1(2
/5ie14=1O-1O1l is suitable. Such conditions Te40 m mφ-230nv φX 200'
nvL -1200 mm1)] can be obtained.

? High-purity quartz glass is produced by dehydrating and vitrifying the porous J-shaped glass. I can only say 1 no. At this time, the heating furnace that performs the dehydration treatment and vitrification is not particularly limited, but it may be a continuous type that performs dehydration treatment and vitrification continuously, or a two-stage type that performs vitrification after dehydration treatment! , Li are used, and the heater of the heat source can be made of SiC, carbon, etc.

As the chlorinating agent used in the dehydration process, for example, C1
, CCl4.5 (1c1., etc.).

However, if a compound other than C12 is used, such as C (+4 or 5OC12), C or S may remain in the glass, so C12 is preferable.

When dehydrating using C12, the treatment temperature is 1.
000°C yet? In Akane, the substitution reaction between chlorine and Oll progresses <<, and when the temperature exceeds 1,300°C, the shrinkage of the porous material H progresses, resulting in C1 remaining in the porous matrix during dehydration and post-processing.
It becomes difficult to replace 2 with the glass-forming atmosphere gas. Therefore, it is necessary to react with 2 at 1,000 to 1,300°C.

After dehydration, vitrification is performed.

In the present invention, it is essential to remove the chlorinating agent remaining in the porous matrix with vitrification atmosphere gas before performing vitrification after dehydration. In the two-stage method, before vitrification, the flow of the chlorinating agent is stopped and the porous matrix is in an open state at a temperature lower than the vitrification temperature - C. The chlorinating agent remaining in the porous matrix is vitrified. All you have to do is remove it by removing the atmosphere. In addition, in a continuous method in which vitrification is performed continuously after dehydration treatment, the porous I4 is opened between the dehydration treatment portion and the vitrification portion at a temperature lower than the vitrification temperature. ] 0 It is also possible to provide a heating zone portion and use this portion to remove the chlorinating agent remaining in the porous matrix +A with the vitrification atmosphere gas.

Processing temperature 1 when dehydrating using C12,
000~1. ．． 3[] At 0°C, the porous Isu shrine is in an open state, so after dehydration treatment, the 02
can be easily removed with vitrification atmosphere gas.

When the temperature exceeds 300°C, the porous material H shrinks and becomes closed, making it difficult to remove 012 within the porous +J month, and C12 remains in the glass.

Therefore, removal will result in either a porous 1-sun shrine or a closed pore state 1,
It is not preferable to carry out the process at a temperature exceeding 300°C, and if the temperature is lower than the dehydration treatment temperature, the temperature may exceed 0.11°C. ! ,! It is appropriate to carry out the dyeing process at a temperature of 1,000° C. to 300° C., which is the same as the dehydration treatment temperature due to the long glass treatment time 1' and 5.

After removing the chlorinating agent in the porous motherboard with a vitrification atmosphere gas, vitrification is performed.

Vitrification is performed at 450°C or higher using a vitrification atmosphere gas.
I, performed at 550°C. For example, dry lle, 0, H2, air, etc. can be used as the vitrification atmosphere gas, but especially if Ilc gas is used, the permeability of quartz glass is good, and bubbles can be easily removed from the glass. Are known. When using a gas with low permeability such as N2, it is difficult to remove bubbles from the closed pore state, and glass bubbles remain. If the vitrification temperature is less than 1.450°C, the glass will become transparent, but if it exceeds 1.550°C, the furnace tube used will be severely worn out, which is not preferable.

By the method 2 below, the wavelength is 200 nm to 2.50 nm.
It is possible to obtain high-purity quartz glass that has a transmittance of 88% or more in a wide wavelength range of 0 nm and has no absorption at <2,730 nm based on 011 stretching vibration.

In addition, the high-purity quartz glass in the present invention takes advantage of the commercial yield and high-speed synthesis characteristics of the VAD method, so high-purity quartz glass can be produced at a lower cost than the plasma method. I can do 1.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, wavelengths from 200 nm to 2,500 nm can be obtained using a simple method and at low cost without requiring complicated operations and expensive equipment such as the plasma method.
1 ] 2 II II It is possible to obtain high purity quartz glass with a transmittance of 88% or more in a wide wavelength range and no absorption at <2,730 nm based on 011 stretching vibration.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited only to these examples.

Example 1 S + Cl 4 was introduced into the center of a quartz multi-tube burner, hydrolyzed in an oxyhydrogen flame to form SiO2 fine particles, and the S + 02 fine particles were deposited to perform MAJ method GOm.
A porous material having a size of mφ×250 mm ml was formed.

? The heated porous base material was placed in the soaking zone of the SiCh-tar electric furnace and the temperature was started to rise. After reaching 1,200°C,
Flow C12 gas at 35n+l/min, 1. ．． 200
Dehydration treatment was carried out at a constant temperature of 2 hours.

After 2 hours, the inflow of C12 gas was started, and then the Ilc gas was started flowing m3'! 120 for 15 minutes at H'g/mid
The temperature was maintained at 0°C and the 012 gas inside the porous paste was removed.

After that, the temperature rate of y1' was set to 06°C/sec and 1. ．．
Rise to 500°C, 1.50 after reaching 1.500°C
The mixture was kept at 0°C for 1 hour to achieve transparent vitrification.

FIG. 1 shows the transmittance curve of the obtained high-purity one-cup glass (t-10 mm).

111 high purity quartz glass has a wavelength of 200 nm
The transmittance was 88% or more in the range from 2.500 nm to 2.500 nm, and no absorption occurred at <2.730 nm based on O1+ stretching vibration.

Example 2 In the same manner as in Example 1 - J method 60IIlllφX
250mm1. A porous shrine? It's 1 no. The obtained porous base material is set in the upper part of the heating furnace, which is continuous from the top to the dehydration treatment section, heating zone section, and vitrification section L 4n
It was gradually lowered at a speed of v/min. length 250 m
The dehydration treatment part of mL was heated to 1,200 °C,
C.I. Gas was introduced at a rate of 35 ml/min to perform dehydration treatment. Length 1. The heating zone part of OOml was heated to 1,200°C in the same way as the dehydration treatment part, and lle gas 3
'l;C/m! 11 and remained in the porous mother moon ] 3 part ],, heated to 500'C, +10 scum 3 XI
Vitrification was carried out in C/InIIn.

1 [I high purity quartz glass has a wavelength of 200 nm
The transmittance is more than 88% in the range from 2 to 500 nm, and < 2 to 730 nm based on the O11 stretching vibration.
No absorption occurred.

[Ratio φ receiving side]

In the same manner as in [Example], porous glue +A was formed and dehydrated. This was immediately made into a transparent glass in the same manner as in Example] without removing the 012 gas.

11.7 The fused silica glass did not exhibit absorption at 2.730 nm based on 011 group stretching vibrations, or
Absorption occurred at ~280 nm.

[Brief explanation of the drawing]

Figure 1 is an example]? FIG. 2 is a diagram showing a transmittance curve of high-purity quartz glass. ]

Claims (1)

[Claims] By hydrolyzing silicon halide in a flame, SiO_2
After forming fine particles and depositing the SiO_2 fine particles to form a porous base material, the porous base material is reacted with a chlorinating agent to perform dehydration treatment, and then vitrified to form quartz glass. In the method of obtaining
A method for producing high-purity quartz glass, which comprises removing a chlorinating agent remaining in a porous base material using a vitrification atmosphere gas.