JPS5924098B2 - Method for producing particulate glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for synthesizing particulate glass by heating a glass-forming gas-phase raw material and a gas-phase oxidizing agent in a high-temperature atmosphere to cause a reaction.

Conventionally, the method of heating glass-forming gas-phase raw materials and gas-phase oxidizing agent to a high temperature to cause a reaction and synthesize fine particulate glass is by heat transfer using a high-temperature wall or a high-temperature reaction tube wall. Reaction energy was used.

For example, as a method for synthesizing SiO2 glass particles, S
iCl4 is transported using an inert gas such as Ar gas or N2 gas, and these gases are heated on the inner wall of a high-temperature nozzle and blown out from the nozzle tip.On the other hand, O2 gas is transported through a separate system and similarly The gases were heated and blown out using the inner wall of another nozzle, and these gases were mixed and reacted to obtain tin-like SiO2 glass. However, in order to fully react SiCl4 and O2, it is necessary to heat the gas itself flowing inside the nozzle to around 1200°C, and to do this, it is necessary to subject the nozzle to even higher and harsher temperature conditions. Ta. For this reason, the material of the nozzle deteriorated significantly, and the selection of the material for the heating element became a major problem. In addition, in an apparatus in which a reaction is carried out by bringing a heating source into contact with a raw material gas, impurities generated from the high-temperature heating source volatilize, making it difficult to obtain a highly pure product.
In order to eliminate these drawbacks, the present invention maintains the nozzle at a relatively low temperature, about the reaction starting temperature of the reaction gas, and applies radiant heat to the gas immediately after it exits the nozzle and is mixed (for example, by applying concentrated infrared light to the gas). It is characterized by causing a reaction by irradiation).

The purpose of the present invention is to prevent material deterioration in the high-temperature parts of the heating element and nozzle by reducing the temperature rise of the heating source and nozzle, and to prevent the volatilization of the heating source material due to high temperature from entering the reaction system. The goal is to obtain a product of purity. Hereinafter, an example in which the method of the present invention is applied to the synthesis of high-purity SiO2 fine particles will be explained in detail. FIG. 1 is a sectional view illustrating an apparatus for synthesizing SiO2 fine particles.

In FIG. 1, reference numeral 1 denotes a raw material supply port, and SiCl4, which is transported by a carrier gas such as ArNa, is flowed into the nozzle inner tube 4 through a connector 3. Reference numeral 2 denotes a supply port for O2, which is supplied to an intermediate portion between the outer nozzle tube 5 and the inner nozzle tube 4 through the connector 3.

6 is a tubular heating element that is powered at one end and heats the nozzle.

T each represents a reaction product. Raw material gas is supplied from the inside 8 of the tube 4, and O2 gas is supplied between the double tubes 4.5.

Each of these gases has a temperature of 800°C near the nozzle exit.
Heated by the nozzle wall until ~900°C.
The reaction gases emitted from the tip of the nozzle diffuse and mix with each other, and as a result, a reaction begins as shown in the following chemical formula. SiC
14+02→SiO2+2C12 FIG. 2 shows the degree of conversion of the above reaction with respect to the reaction system temperature.

As can be seen from Figure 2, the starting temperature of this reaction is 800°C.
It can be considered as before and after.

That is, the reaction gas heated to 800 to 900 DEG C. that exits the nozzle contains some particulate SiO.
When radiant heat is applied to this atmosphere, for example, when irradiated with a focused red light beam, SiCl4, O
Although the red line passes through gases such as 2, Cl2, and Ar, SiO2 fine particles absorb some of the red line energy and increase the temperature of the fine particles themselves. The gas that collides with the SiC2 particles whose temperature has increased receives energy and the temperature of the reaction system also increases. In other words, the presence of SlC2 fine particles allows the red male ray energy to be taken into the reaction system, resulting in SiCl4
→It leads to increasing the conversion rate to SiO2. In this way, in the case of the SiO2 glass system, the temperature of the reactant gas near the nozzle tip does not rise above 1100°C.
The conversion rate of SiCl4 to SiO2 can be increased to 100% at a temperature of about 00 to 900°C. According to the method for producing particulate glass according to the present invention, even if the oxidizing gas is ejected from a heating nozzle at a relatively low temperature, the reaction can be reduced to 100% by applying energy such as a red line to the mixed gas.
(!) It is done.

Therefore, the nozzle is not deteriorated, and a highly pure product can be obtained without contaminating the produced reaction product with impurities from the material of the nozzle. The description of the method according to the invention is based on fine-grained Si
Although the synthetic system of O2 glass has been described, the present invention can be similarly applied to other glasses, such as GeO2, p2O5, B2O3 glass, etc., or multi-component fine particulate glass made by mixing these glasses.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a method for synthesizing SlO2 fine particles, where 6 is a heating element, 7 is a generated soot, 8 is SlCl4+carrier gas, and 9 is 02 gas.

FIG. 2 shows the dependence of the reaction temperature on the conversion rate via SlO in the high-temperature gas phase oxidation reaction of SlCl4.

Claims (1)

[Claims] 1. A method in which at least a glass-forming raw material and an oxidizing gas are introduced separately into a nozzle, and the nozzle is heated to a temperature higher than the starting temperature of the reaction by injecting them, diffusing and mixing them, and reacting in a high-temperature atmosphere to produce particulate glass. 1. A method for producing particulate glass, characterized in that radiant heat is applied immediately after the heated raw material gas and oxidizing gas are injected from a nozzle to accelerate the reaction.