JPS5919894B2 - Manufacturing method of anhydrous glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing glass using an oxygen decomposition reaction method of silicon tetrachloride SICl4, in which a reaction area on the glass surface is irradiated with ultraviolet rays, or at the same time, chlorine gas Cl is applied to the reaction area.
The present invention relates to a method for producing anhydrous glass in which mixing of hydroxyl groups OH into the glass is suppressed by supplying 2.

It has been revealed that in the conventional method of obtaining high-strength glass for optical transmission by vapor-phase hydrolysis of SiO14, OH is mixed into the glass, which significantly impairs the optical transmission characteristics. .

As a solution to these problems, for example, a method of acid-decomposing SiCl4 is well known as a method of manufacturing anhydrous glass.
According to this oxygen decomposition method, although OH groups should not be generated in principle, products mixed with OH are obtained depending on the situation. This is because the raw material gas SiCl4 contains trace amounts of hydrogen-containing substances such as chlorosilanes SiCl3H, SiCl2H2, and SiClH3, which are decomposed with oxygen and become OH.
This is due to the fact that There are also limits to the purification of raw material gas, and it is extremely difficult to completely remove OH. The present invention has been made in view of the above points,
The present invention provides a method for producing anhydrous glass in which the chlorination of hydrogen in chlorosilane is promoted and the generation of OH is suppressed by irradiating an oxygen decomposition reaction part with ultraviolet rays or simultaneously supplying chlorine gas Cl2.

The present invention will be explained in detail below with reference to Examples.

FIG. 1 is a configuration diagram showing an embodiment of the present invention. The quartz tube 1 is attached to the rotary heating device 2. The rotary heating device 2 includes bearings 2a and 2b that rotatably support the quartz tube, a motor (not shown in the figure) that rotates the quartz tube, and an oxyhydrogen burner 2c that heats the quartz tube while moving at a constant feed speed. It consists of A gas supply pipe 4 is connected to a connection end 3 provided at one end of the quartz tube, and this is branched to connect a gas supply device to each end via stop valves 5a, 5b, . . . 5d. T is a SiCl4 liquid reservoir whose liquid temperature is maintained at a constant value of about 10° C. by a constant temperature bath 8, into which oxygen gas 02 whose flow rate is adjusted to about 20 go/min by a flow rate control valve 9 is blown.

The SiCl4 vapor thus generated is sent into the quartz tube together with 02 by opening the valve 5a. At the same time, 02, whose flow rate is adjusted to about 500 m1/min by the flow rate control valve 14, is sent into the quartz tube 1 by opening the valve 5d. The oxygen decomposition reaction expressed by the following formula is carried out with SiCl2 supplied inside the heated quartz tube 1. The resulting tin of silicon dioxide SlO2 adheres to the inner surface of the quartz tube, and the burner 2c approaching 1800℃
When it reaches a certain high temperature, it melts and becomes vitrified.

The Cl2 is led to the treatment device via a discharge pipe 16.
As already mentioned, SiCl4 contains a trace amount of chlorosilane as an impurity, and when this causes an oxygen decomposition reaction, it becomes 0.
SiO2 tin containing H groups is produced.

In this embodiment, the power consumption of the ultraviolet irradiation device 15 is set to 80 W/CnL, for example, so that the chlorination reaction of chlorosilane by Cl2 produced as a result of the oxygen decomposition reaction of SiCl4 is promoted more than the above-mentioned oxygen decomposition reaction. Ultraviolet rays were irradiated onto the reaction area on the quartz glass surface using two mercury lamps arranged in series so as to be able to irradiate over a length of 50 cnL. The currently used quartz glass tubes are commercially available and do not transmit ultraviolet rays with a wavelength of 250 nm or less. In the case of the mercury lamp, substantially 250 to 35
Spectral components in the 0 nm range act effectively within the quartz tube. This chlorination reaction is expressed by the following chemical reaction formula. Since the chemical reaction represented by the Kowa I formula has an extremely high reaction rate, chlorosilane is completely converted to SiCl4, resulting in the formation of anhydrous glass with a low content of 0H groups. The occurrence of the reactions of formulas (2) to (4) is supported by experimental results showing that the content of SiCl2H is reduced by bubbling Cl2 into SlCl4 containing SiCl3H and irradiating it with ultraviolet light. It is being In this way, the constant supply of raw material gas, the irradiation of ultraviolet rays, and the reciprocating movement of the oxyhydrogen burner (
Feed rate of approx. 150 dew/min), rotation of quartz tube (approx.
r. p. By combining step m), it is possible to form anhydrous glass with a uniform thickness on the inner surface of the quartz tube.

It is clear from the above explanation that chlorination of chlorosilane is further promoted by supplying excess Cl2 to the reaction section in addition to Cl2 produced by the oxygen decomposition reaction of SiCl4. The flow rate is adjusted to 10 m1/M by the flow control valve 13.
This objective can be achieved by supplying Cl2 adjusted to about ln into the quartz tube by opening the valve 5c. Example 1 Using the apparatus shown in FIG. 1, conventional product (no ultraviolet irradiation, no Cl2 supply) and invention product I (
Ultraviolet irradiation) A product of the present invention (ultraviolet irradiation, Cl2 supply) was created.

A piece of glass was cut out as a sample from the obtained product; 2.
When the extinction coefficient at 73 μm was measured using an infrared spectrometer,
The 0H content was as shown in Table 1. The above is a case of obtaining anhydrous SlO2 glass, but as a means for obtaining a photoconducting glass, GeC
It is well known that doped quartz glass having an arbitrary refractive index can be obtained by simultaneously supplying additives such as 14, POCl3, and BCl3 into a glass tube.

Therefore, for example, when it is desired to obtain anhydrous glass in which GeO2 is added to SiO2, the following operation may be added. Ge maintained at a constant value of around 10°C by thermostat 11
10 m in the Cl4 liquid reservoir 10 by the flow control valve 12.
GeC is injected with 02 adjusted to a flow rate of about 1/Min.
Gas 14 is generated, valve 5b is opened, and gas 02 is sent into the quartz tube. GeO2 generated by oxygen decomposition of GeCl4 mixes with tin of SiO2, and heats up to 1400'C.
Ge is doped into the anhydrous glass that is melted and formed at a certain level. Example 2 Using the apparatus shown in FIG. 1 and under the same conditions as described above,
SiO2-GeO2 by the conventional method and the method of the present invention
produced glass.

A sample piece was cut out from the obtained product, and the extinction coefficient at 2.73 μm was measured using an infrared spectrometer in the same manner as in Example 1, and the 0H content was as shown in Table 2.
Another embodiment of the present invention is applied to the so-called plasma torch method, as shown in FIG.

A mixed gas of argon, 02, and SiC14 is introduced to the tip of the pipe 22. Coil 23 at the tip of the pipe
The plasma torch 24 is generated by high-frequency heating. The quartz rod 20 is attached to a rotating rod 21 and rotated. By irradiating the reaction area on the surface of the quartz rod with ultraviolet rays using the ultraviolet irradiation device 25, the oxygen decomposition reaction of the first formula and the chlorination reactions of the second to fourth formulas occur, and anhydrous glass is formed on the surface of the quartz rod. . As explained above, according to the method of the present invention, hydrogen-containing substances such as chlorosilane contained in the raw material gas can be chlorinated, so anhydrous glass with a suppressed amount of hydroxyl groups can be produced, resulting in lower optical fiber loss. It has a huge contribution to make.

[Brief explanation of drawings]

FIG. 1 is a drawing showing an embodiment of the present invention, in which 1 is a quartz tube, 2c is an oxyhydrogen burner, 7 is a SlCl4 liquid reservoir,
10 is a GeCl4 liquid reservoir, 13 and 14 are flow control valves for chlorine gas and oxygen gas, respectively, and 15 is an ultraviolet irradiation device.

Claims (1)

[Claims] 1. While irradiating ultraviolet rays to a reaction area on the heated glass surface, SiCl_4 or an additive consisting of SiCl_4 and a metal chloride is decomposed with oxygen in the reaction area to form Si on the surface.
A method for producing anhydrous glass, which comprises depositing a glass powder made of O_2 or SiO_2 and a metal oxide, and heating and melting the powder. 2 While supplying chlorine gas to the reaction area on the heated glass surface and irradiating it with ultraviolet rays, SiCl was removed in the reaction area.
_4 or SiCl_4 and an additive made of a metal chloride are decomposed with oxygen to deposit a glass powder made of SiO_2 or SiO_2 and a metal oxide on the surface, and the powder is heated and melted. Method.