JPS61281037A - Production of deposited glass soot - Google Patents

Abstract

PURPOSE:To produce deposited glass soot easily and stably in high yield, by rotating a starting material under heating, and depositing glass soot generated from a glass-soot synthesis burner to the starting material. CONSTITUTION:A columnar or cylindrical starting material 11 (e.g. quartz tube) is rotated around its own axis. A glass-soot synthesis burner 13 placed near one end of the starting material is supplied with fuel gas (H2), combustion- assisting gas (O2) and glass raw material to form a flame 14, in which glass soot is generated. A starting material heating burner 15 is placed close to the synthesis burner 13. The starting material 11 is heated with the flame 16 of the burner 15, and the burner 13 is transferred relative to the starting material 11 parallel to the axis of the material 11 to effect the formation of the deposited glass soot 12 on the circumference of the starting material 11.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for forming an aggregate of glass particles on the outer periphery of a cylindrical starting material, and is particularly applicable to the production of an optical fiber base material that requires high purity. The present invention relates to a method for forming a glass fine particle deposit deposited on the outer periphery of a starting material, which is suitably used as an intermediate product in the process.

[Conventional technology]

Conventionally, as a method for manufacturing a base material for a quartz-based glass tube or an optical fiber, there is a so-called external method as disclosed in Japanese Patent Application Laid-open No. 73522/1983.

In this method, as shown in FIG. 3, 8i0. A fine glass particle deposit body 12 is formed by depositing fine glass particles such as, etc., and after depositing a predetermined amount, the deposition is stopped, the starting material 11 is pulled out, a pipe-shaped glass aggregate is formed, and the pipe-shaped glass aggregate is The body is sintered into transparent glass in a high-temperature electric furnace to obtain pipe-shaped glass. Alternatively, by using a solid glass base material for optical fiber as the starting material 11 in a similar manner, a composite of the starting material and the glass fine particle deposit 12 formed on its outer peripheral part' is formed, and then the starting material 11 is We have also considered a method of forming an additional transparent glass layer on the outer periphery of the starting glass base material for optical fiber by heat-treating the composite in a high-temperature furnace and sintering the part of the glass particle deposit without drawing it out. It will be done.

[Problems to be solved by the present invention]

In the above method, conventionally, one or more burners 15 for producing glass particles are used to synthesize a glass particle deposit as shown in FIG. Generally, Hl is used as fuel gas from the burner tip.

Os, air, etc. are supplied as combustion assisting gases such as cH4, Cs&, etc., and a flame 14 is formed. Here, as a raw material for glass,
5iC4t GeCt4 etc. are supplied, causing a hydrolysis reaction to produce glass fine particles, Sing, Ge01
etc. are generated. The fine particles adhere to the rotating starting material 11, and a glass fine particle deposit 12 is formed.

A particular problem in producing a glass particle deposit by this method is the problem of cracks in the glass particle deposit 12. The cracks in the glass fine particle deposit 12 are caused by
This is caused by the low bulk density of the glass particles, and the usual countermeasure is to increase the flow rate of the fuel gas to make the glass particle deposit 12 harder, that is, to increase the bulk density. However, in the case of the glass particle deposit 12 formed on the outer periphery of the rotating starting material 11, even if the amount of fuel gas was slightly increased, it was insufficient to prevent the deposit 12 from cracking.

Furthermore, when the amount of fuel gas was increased significantly, the starting material 11 was deformed, causing the central axis of the starting material 11 to be misaligned with the rotating axis, causing the problem that the starting material 11 moved around. Starting material 11
When whirling occurs, the starting material 11 in the synthesized glass fine particle deposit 12 becomes eccentric, making it impossible to obtain a base material with good axial symmetry. The problem of cracking of the base material becomes particularly noticeable as the outer diameter of the starting material 11 increases. Furthermore, since the flame temperature is too high, the particle temperature is higher than the maximum temperature, resulting in a problem of poor raw material yield.

A more detailed investigation of the above-mentioned base material cracking phenomenon revealed that when the base material cracks, it cracks as if it were to burst open, and that most of the glass particle deposits that had accumulated around the outer periphery of the starting material had peeled off from the starting material. I found out. From this, it was predicted that the glass fine particle deposits attached near the surface of the starting material were very soft. Therefore, we measured the bulk density (215113) distribution in the radial direction of the synthesized glass fine particle deposit and found that the bulk density near the surface of the starting material was lower than that outside, as shown in Figure 4. I found out that From this, it was found that the main cause of cracks in the glass particle deposit was the accumulation of soft glass particles near the surface of the starting material. Now, it is thought that the cause of the accumulation of soft glass particles lies in the starting material itself. That is, since the starting material reaches the glass fine particle depositing part without being particularly heated, it is heated by the glass fine particle forming burner while the glass fine particles are attached. For this reason, it is thought that the glass particles adhering near the surface of the starting material absorb heat from the starting material, resulting in a decrease in temperature and a soft deposit. In addition, since the starting material itself has thermal conductivity, it is thought that heat is constantly removed from the starting material in the longitudinal direction, and it is thought that it is necessary to control the temperature of the starting material in order to stably attach the glass particles. It will be done. It is obvious that this becomes a particularly serious problem as the outer diameter of the starting material becomes larger.

[Means for rounding to solve the problem] The present invention aims to overcome the above-mentioned problems and stably produce a glass fine particle deposit. The aim is to synthesize glass fine particle deposits while heating the starting materials, making production stable and easy.

That is, in the present invention, from near one end of a substantially cylindrical or cylindrical starting material rotating about its own axis,
Glass particles generated by supplying a glass raw material into the flame of a burner for glass particle synthesis are started to be deposited on the outer periphery of the starting material, and the burner is moved relatively parallel to the axis of the starting material. In the method of forming a deposit of glass fine particles in the axial direction on the outer periphery of the starting material, the starting material heating device is installed adjacent to the glass fine particle synthesis burner, and the starting material is This is a method for manufacturing a glass fine particle deposit, characterized in that the glass fine particle deposit is manufactured while heating the glass fine particle deposit.

Further, it is preferable to use a burner for heating the starting material as the device for heating the starting material, and to heat the starting material with a flame formed by the burner.

The present invention will be described in detail below based on Examples. The configuration of an embodiment of the present invention is shown in FIG.

In FIG. 1, glass particles are generated by flame hydrolysis in a flame 14 formed by a burner 13 for synthesizing glass particles with a fuel gas and a heating gas ORN source gas flowing through the burner. The glass particles are deposited on the outer periphery of a starting material 11 that rotates and moves relative to a burner for synthesizing glass particles to form a glass particle deposit 12. In addition to this configuration, in the present invention, a burner 15 for heating the starting material is installed adjacent to the burner 13 for synthesizing glass particles in order to control the temperature of the starting material 11. , 0 heating gas! and by flowing seal gas Ar, a flame 16 is formed,
The starting material 11 is heated by this flame 16.

The flow rate of the fuel gas fed into the starting material heating burner 15 should be adjusted so that the starting material 11 is not deformed by this heat, and the flame 16 should be positioned so as not to disturb the flame 14 of the glass particle synthesis burner 13. It is necessary to install a burner for heating the starting material at

(Example) In the configuration shown in FIG. 1, a concentric multi-tube burner was used as the glass particle synthesis burner 15, a quartz glass tube was used as the starting material 11, and a glass particle deposit was formed on the outer periphery thereof.

03 was used as the fuel gas, 03 was used as the auxiliary combustion gas, and 5iC4 was used as the raw material. As for the flow rate conditions, SiC'
4=2000CC/m, H2=501/m, O.

=4 ot/=, Ar=20 t/-.

A concentric multi-tube burner as a starting material heating burner 15 is installed below this burner for glass particle synthesis in parallel with the burner for glass particle synthesis, and H2=10.
t/m, OH=15L/m, Ar=
The starting materials were heated by flowing 5 t/- of gas. The surface temperature of the starting material at this time was maintained at 700°C to 800°C. As a result, the base material could be manufactured very stably, and the problem of cracks in the base material could be solved.

In addition, since the flow rate conditions of the burner 15 for glass particle synthesis could be set only for the synthesis of the deposit, the yield of the glass particle deposit 12 was as high as 9, with a deposition rate of 5 f/m and a yield of 6.
It was possible to synthesize it at 2%. When the bulk density distribution in the radial direction of this deposit 12 was measured, the results were as shown in FIG.
It was found that the decrease in bulk density at the surface of the starting material was +n positive.

In this example, a flame formed by a burner was used as the starting material heating device, but the same effect can be expected even if other heating means are used. In addition, only 5iCt4 was used as the input raw material, but in addition to this, GeCl4
, POC43, etc. may be mixed, and the effects of the present invention will not be impaired even if the number of burners for glass particle synthesis is plural.

[Effects of the present invention]

When the method of the present invention synthesizes a glass fine particle deposit on the outer periphery of a starting material such as quartz-based glass, the glass fine particle deposit can be produced stably, easily, and with good yield.

[Brief explanation of drawings]

FIG. 1 is a schematic illustration of an embodiment of the present invention, FIG. 2 is a graph showing the dimensionless radial bulk density distribution of the glass fine particle deposit obtained by the present invention, and FIG. 3 is a schematic explanation of the conventional method. FIG. 4 is a graph showing the bulk density distribution of the glass fine particle deposit obtained by the conventional method.

Claims (2)

[Claims] (1) From near one end of a substantially cylindrical or cylindrical starting material that is rotating about its own axis, a glass raw material is introduced into the flame of a burner for synthesizing glass fine particles onto the outer periphery of the starting material. By starting to deposit the glass particles generated by supplying the material and moving the burner relatively parallel to the axis of the starting material, a deposited body of glass particles is formed in the axial direction on the outer periphery of the starting material. A glass fine particle deposit body characterized in that the above starting material heating device is installed adjacent to the above glass fine particle synthesis burner, and the glass fine particle deposit body is manufactured while heating the above starting material. manufacturing method. (2) A claim in which, as a starting material heating device, a starting material heating burner is installed adjacent to a glass particle synthesis burner, and the starting material is heated by a flame formed by the heating burner. The method for producing a glass particle deposit according to item (1).