JPS5888130A - Manufacture of fine glass particle - Google Patents

Abstract

PURPOSE:To manufacture transparent glass particles having large diameter, by synthesizing fine glass particles by the flame hydrolysis or thermal oxidation reaction of the vapor of glass-forming halide, and exposing the particles again to an atmosphere of the halide at high temperature. CONSTITUTION:A halide such as SiCl4, GeCl4, etc. is subjected to the flame hydrolysis or thermal oxidation reaction to obtain fine glass particles (hereinafter referred to as ''primary particles''), and the primary particles are exposed again to an atmosphere of a halide such as SiCl4, GeCl4 etc. at high temperature. The growth of the primary particle is accelerated, and glass fine particles having the optimum particle size for the production of high-quality doped silica glass free from residual bubbles can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of silica glass particles having large particle sizes.

Conventionally, in a method for producing silica glass for optical fibers, particularly doped silica glass, glass forming raw material gases such as silicon tetrachloride vapor and dopant such as germanium tetrachloride vapor are subjected to flame hydrolysis or heat using a flame burner or the like. It oxidized and produced glass particles. In this case, since the glass particles are generated by a reaction from the gas phase to the same phase, the particle size d1 is the flame hydrolysis (
500-2000A at 1000-1300℃)
100-5 in case of thermal oxidation (1ooo-1300℃)
It was extremely small at 00A.

On the other hand, in order to produce transparent doped silica glass without bubbles at high speed by supplying glass particles into a flame or plasma flame and melting them, the size of the particles is 10 to 1 in diameter.
It has been experimentally revealed that the optimum particle size is about 50 m, and that bubbles remain in the doped silica glass if the particle size is smaller than this.

Therefore, it is very difficult to produce doped silica glass without residual bubbles by supplying glass particles produced by conventional methods to a flame or plasma flame and melting them. .

Furthermore, when doped silica glass is produced using a plasma flame from glass fine particles having a small particle size obtained by such conventional methods, there is a drawback that the deposition efficiency of the glass fine particles is poor.

The present invention has been made to solve the above-mentioned drawbacks, and provides a method for producing glass fine particles having a diameter that is optimal for producing surface-quality doped silica glass that does not contain residual air bubbles.

To summarize the present invention, the first method for producing glass particles according to the present invention involves subjecting a halide such as silicon tetrachloride or germanium tetrachloride to a flame hydrolysis reaction or a thermal oxidation reaction to produce glass particles (hereinafter referred to as secondary particles). After the glass particles are produced, the glass particles are again exposed to an atmosphere of a halide such as silicon tetrachloride or germanium tetrachloride at high temperature.

The second method for producing glass particles according to the present invention is 5iC4
, H! The doped silica glass particles formed by exposing the glass fine particles powder or crystal powder to a doped silica glass forming gas consisting of a gaseous additive that can react with O and O to form a dopant solid solution are heated again at high temperature. Same as -
Alternatively, it is characterized by being exposed to the same doped silica glass forming gas.

According to the method for producing glass fine particles according to the present invention, the primary particles produced by the conventional method are exposed to an atmosphere of halides such as silicon tetrachloride and germanium tetrachloride, so that the primary particles become the nucleus and form the particles. Growth is significantly promoted and glass powder with a large particle size (hereinafter referred to as secondary particles) can be obtained.

The present invention will be explained in more detail.

The primary particles used in the first aspect of the present invention are s i ox fine particles synthesized by flame hydrolysis or thermal oxidation of halide vapor for glass formation and dopant addition 5
If it is a book that is fine particles and can be melted to obtain a glass body, it is particularly limited.

The primary particles used in the second invention according to the present invention are SICM, H*0. Reacts with the above &O to form StO,-
Doped silica glass fine particles synthesized by exposure to a doped silica glass forming gas consisting of a gaseous additive capable of forming a dopant solid solution, such as Stow-060g
Glass particles, SiO! -Gl! 01 crystal powder etc.

The gaseous additive is not particularly limited, but for example, G
eC4, POC4, Pct@, TiC4, BBg
.

It can be one or more of PC/, etc.

In the present invention, in both the first and second inventions, grain growth of the -order particles is promoted by exposing the -order particles to a halide atmosphere under a pseudo temperature. The halide type may be the same as the doped silica glass forming gas used to form the halide or dopant used in the production of the primary particles, or may be the same type of gas with a different composition. However, from the viewpoint of the quality of the secondary particles, it is desirable that they be the same. For example, S
low-Gl! +02 When producing solid solution secondary particles, - 5iC4 for both the raw material for producing carbon particles and the raw material for producing secondary particles.
When 5ick and GeC are used, the concentration distribution of G in the produced secondary particles is almost uniform, but when 5ick is used alone as the raw material for producing secondary particles, the Ge concentration in the produced secondary particles is almost uniform. The concentration distribution is such that Ge is present in the center (primary particles), and almost no Ge is present in the surrounding area.

The halide that causes the grain growth of such secondary particles is not particularly limited, but for example, SiC4, GeC4e, etc.
POCls * PCI4t Tf C1s +
BBrs W BO2 and the like (however, silicon halides must always be included).

The grain growth rate of the primary particles according to the present invention is determined by the halide supply im(4) when the primary particles are exposed to a halide atmosphere.
It is mainly controlled by SIC4), which is the main raw material in I, the ambient temperature, and the reaction time. Conventionally, the halide supply method for obtaining glass fine particles from a halide was to supply halide vapor using a carrier gas; however, in the present invention, the same method as the conventional supply method may be used.
The carrier gas NIK4 must be selected depending on whether the halide is subjected to a flame hydrolysis reaction or a thermal oxidation reaction. In the former case, Ar gas or N gas is used; in the latter case, O gas is used. The reaction efficiency is high, and in both reactions, the vapor pressure of the halide is 200% for silicon halide (for example, SiC), which is the main raw material.
A range of ~1000 threshold HP is optimal. If the amount of silicon halide is less than 200 mm Ht, the temperature control becomes short and grain growth becomes difficult.
This is because if the temperature exceeds 000 mm HP, it becomes difficult to control the temperature.

In this way, primary particles are grown using a halide, and although the atmospheric temperature varies depending on the flame hydrolysis reaction and thermal oxidation reaction, it is preferable to grow the particles at a temperature of 300 to 1800°C. If the temperature is below 300°C, the reaction time will become long, the reaction efficiency will be extremely poor, and grain growth will not be promoted. Further, if the temperature exceeds 1800°C, glass fine particles will no longer be generated. Further, the heat source is not particularly limited, such as an oxyhydrogen flame, a plasma flame, or an electric furnace, as long as a desired temperature is desired.

The reaction time is preferably determined functionally, taking into account the amount of halide supplied, the ambient temperature, the amount of primary particles supplied, and the like.

In the first method for producing glass fine particles of the present invention, it is also possible to carry out the production of primary particles and the production of secondary particles continuously, and in both the first and second inventions, the production of secondary particles and the production of silica glass Alternatively, it is also possible to manufacture doped silica glass continuously.

The present invention will be explained in detail below.

Figures 1 and 2 are an example of an apparatus for carrying out the method according to the present invention. Figure 1 is a schematic diagram of an apparatus for producing secondary particles from primary particles, and Figure 2 is a FIG. 1 is a schematic diagram of an apparatus for continuously producing primary particles and secondary particles.

#141 In the diagram, 1 is the primary particle, 2 is the reaction tube, 3 is the electric furnace, 4 is the secondary particle, 5 is the secondary particle collection container, 6 is the exhaust port, 7 is 5i (container for 4, 8 is for GaCl2) Reference numeral 9 is a pipeline for conveying the reactant gas.In addition, in FIG.
22 is a reaction tube, 23 is a secondary particle collection container, 24 is a gas inlet for preventing primary particle diffusion, 25 is an exhaust port, 26.27 is an electric furnace, 28 is a primary particle, 29 is a secondary particle, 30.32
1 is a container for StC. 33 is a container for GeC. 34 is a container for StC.
．． 35 is a reactant gas transport pipe line.

Example 1 Using the apparatus shown in Fig. 1, doped silica glass particles 1 having a particle size of 500 to 2000 A to which 10 mol of G. 2, while the SIC container 7 and G
From the eC/4 capacity a8, the vapors of sic/14 and GeC are sent to the reaction tube 2 via the reaction gas transport pipe 9 using fake gas, and the secondary particles 1 are transferred to 5ICt4, Ge
It was exposed to a reaction gas containing C4 and H2 gases.

The composition of the reaction gas at this time is 5iC420 mol 1 Ge
C42 mol%, O! The feed rate was 2 tons per minute at 78 molti.

Further, the temperature of the reaction tube 2 was maintained at 1400° C. by an electric furnace 3.

As a result, the growth of primary particles progresses inside the reaction tube 2,
The secondary particles 4 added to Ge are transferred to the secondary particle collection container 5.
obtained. The particle diameter of the obtained secondary particles was measured and was 10 to 1004 m''.

The large-sized secondary particles obtained in this way are melted using flame or plasma flame, and are transparent and contain no residual air bubbles.
It was possible to produce doped silica glass at a high speed of about 2009/min.

Implementation 1 + I12 Discharge to Cape Minato in Figure 2 and prepare the reaction tube 21 in advance.
and 22 mW by electric furnaces 26 and 27 at 14
After holding at 00°C, the temperature for 5IC14: (0 and G
eC! From the container 31 for 0! The structure of the reaction tube 21, in which SiC and GeC^ vapors are sent to the reaction tube 21 by gas, is a double structure with the liquid PlrIi entering the electric furnace 26.
, GeC'14 and 0. The reaction gas containing gas is 2
It was sent to the center pipe of the heavy pipe structure. The composition of the reaction gas at this time was 5ic4 mol, GeC 2 mol, and 78 mol, and the supply rate was 21 mol/min.

- 5 tons of Ar gas from the secondary particle diffusion prevention gas inlet 24;
A mixed gas of 5 t/ml of mln and 5 t/ml of gas was introduced to prevent primary particles generated inside the reaction tube 21 from diffusing and adhering to the inner surface of the reaction tube 21.

tfcstct4 container 32 and GeC4 container 33
From there, the gas is transported through the reactant gas transport pipe 35.
cm and GeC4 vapors were sent to reaction tube 22. The composition at this time was the same as that of the reaction gas for producing primary particles described above.

As a result, secondary particles 29 were continuously obtained in the secondary particle collection container 23. When the particle size of the obtained secondary particles was measured, it was found to be 7 to 180 m. For comparison with the conventional method, the supply of vaporized raw materials from the reaction scum cap feeding pipe 35 to the reaction tube 22 was stopped, and the particle size of the particles obtained at this time was measured and found to be 100 to 500A. . This result shows that primary particles 28 with a particle size of 100 to 500A are generated inside the reaction tube 22, and primary particles 28 are generated inside the reaction tube 22.
This book shows that grain growth rapidly progresses with No. 8 serving as a nucleus, producing secondary particles with a large grain size.

As described above, according to the method for producing glass particles according to the present invention, since the glass particles obtained by the conventional method are used as nuclei for grain growth, it is possible to easily produce glass particles with a large particle size, and each particle F′i, It has the advantage of being able to produce completely transparent products.

Further, if doped silica glass is produced by introducing the glass particles thus produced into a flame or plasma flame, there is an advantage that doped silica glass containing no residual bubbles can be produced efficiently at high speed.

Furthermore, manufacturing an optical fiber using the doped silica glass manufactured in this manner has the advantage that the cost can be reduced.

[Brief explanation of the drawing]

Figure 1 and Figure 2 are an example of an apparatus for carrying out the method according to the present invention. 1 is a schematic diagram of an apparatus for continuously producing secondary particles; FIG.

Claims (1)

[Claims] 1. Glass fine particles synthesized by subjecting the vapor of a halogenide for glass formation to a flame hydrolysis reaction or a thermal oxidation reaction are again exposed to a halogenide atmosphere at a high temperature. A method for producing glass fine particles. 2, 5tct4. Reacts with so and ao and SIO
,-)"-Glass fine particles are exposed to a doped silica glass forming gas consisting of a gaseous additive capable of forming a panto solid solution. A method for producing glass particles whose percentage is determined by exposure to a logidizing atmosphere.