JPS5978943A - Manufacture of glass containing fluorine - Google Patents

Abstract

PURPOSE:To obtain high-purity glass contg. fluorine at a low cost by using SiCl4 and a gas contg. fluorine as starting materials for synthesizing glass and by bringing them into reaction in a flame using a specified gas to form fine paticles. CONSTITUTION:Starting materials for synthesizing glass are introduced into a flame and allowed to react in the flame to form fine particles, and the particles are deposited on a starting member to synthesize glass. In this method, a halogen compound such as SiCl4 and a gas contg. fluorine such as gaseous flon are used as the starting materials, and gaseous hydrocarbon contg. hydrogen in <=1.0 ratio of H/C in the molecule or a gas contg. no hydrogen such as CO, C2N2 NOx or CS2 is used as a gas for forming the flame. Gaseous acetylene easy to handle is preferably used as the gas for forming the flame because it gives a high temp. and has low toxicity.

Description

Detailed Description of the Invention Technical Field of the Invention The present invention relates to optical fiber cladding materials, core materials used for special purposes such as infrared transmitting optical fibers, and other materials with low refractive index and low refractive index due to the inclusion of fluorine. The present invention relates to a method for producing a fluorine-containing glass that is used as a dispersion glass and has extremely low impurities.

BACKGROUND OF THE TECHNOLOGY Conventionally, as a method for synthesizing glass based on gas phase response, a method for synthesizing 802 and the like by flame hydrolysis using an oxyhydrogen flame is known. This method uses a flame, so it has good energy concentration and thermal efficiency, and the hydrolysis has a fast reaction rate, so it can increase the synthesis rate.

However, even if you try to add fluorine gas to the raw material gas and add fluorine into the glass (for example, Sin), you will hardly be able to dope it.This is due to the following (1) to (5).
The reaction shown in (5) mainly occurs, but if a large amount of H2O is present, the reaction shown in (5) causes the S
This is thought to be because the equilibrium concentration of iF becomes extremely low.

(1) StC14+2H20-4SiO2+4HCl(
2) CC12Ft + 02 - CO, 10C1
, +2 (F) (3) 5iC1a +4 CF)
→StF+ + 2C't(415tOt +4 (F
) →3iF, +02(5) SiF, +2H2
0-5in2+ 411F Conventional technology and problems In the conventional glass synthesis method, which synthesizes 5i02 etc. by flame hydrolysis using an oxyhydrogen flame, as mentioned earlier, it is difficult to incorporate fluorine into the glass. I could hardly do it. In addition, there is a method that uses electromagnetic energy (a plasma flame that forms a flame from two sources) in order to increase the fluorine yield by increasing the number of reactions that do not involve water, but this method requires equipment. This poses a problem in that it is extremely large in size, resulting in high equipment costs, and requires advanced technology because the torch is likely to deteriorate and stable operation is difficult.

Purpose of the Invention The present invention solves the problems of the conventional art, and uses a dihalide C as a raw material for glass synthesis and a fluorine-containing gas, and uses a hydrocarbon gas with a molecular element ratio of 110 of 1.0 or less as a flame-forming gas. Alternatively, the method is characterized in that a flame reaction is carried out using a gas that does not contain hydrogen element, and its purpose is to provide a method for producing high-purity fluorine-containing glass at low cost.

Embodiments of the Invention The present invention uses a helogne compound such as 5iC14 and a fluorine-containing gas such as chlorofluorocarbon gas as raw materials for glass synthesis, and as a flame forming gas, an element ratio of II/C of the molecules of the gas is 1. It is characterized by carrying out a flame reaction using a hydrocarbon gas with a hydrogen content of 0.0 or less or a gas containing no hydrogen such as Co, CN, NOx, C8, etc. Further, as the flame-forming gas, it is convenient to use C, II2 gas, which can provide high temperature and is easy to handle because of its low toxicity. If you want to further increase the fluorine concentration in the glass, use CO.

02N2. Gases that do not contain hydrogen at all, such as NOx and C82, are preferable. Furthermore, when a higher temperature is required to increase the reaction rate, CN is preferable. As the fluorine-containing gas, fluorocarbon gases such as CCI, F, etc. are suitable because they are inexpensive, easily available, and easy to handle.

According to the present invention, it is possible to relatively easily obtain a fluorine concentration of about 'I, wt% (about 0.6% relative refractive index difference with Sio2) using fluorine-doped quartz glass. . It has not been easy to obtain molecular glass as a flame-forming gas.

Examples of the present invention will be shown below.

Example 1: Using 5iC14 and CC12F2 as raw materials for glass synthesis and C and H2 gases as flame forming gases, these gases were introduced into a concentric quadruple tube burner under the conditions shown in the table below to form a flame. At the same time, glass particles were generated and deposited on a quartz rod that rotated and moved from side to side.

This deposited body was inserted into a furnace at about 1300° C. to be melted and made transparent. When the refractive index value of the obtained transparent glass was measured, S
A glass with about 0.4% lower tOx was obtained.

Example 2: Glass was synthesized using B2 as the flame-forming gas and under almost the same conditions as Example 1, and the refractive index value was 0.1 to 0 relative to 5in2. .2
% lower glass.

Example 6: Using 02N2 as the flame-forming gas, a flame was formed under almost the same conditions as in Example 1, glass particles were generated, and a flame was placed on a quartz rod that rotated and moved from side to side. The fine glass particles were deposited, and the speed at which they were moved was adjusted to maintain the temperature of the deposited portion high using the heating of the flame, thereby forming a glass layer in a molten state. The refractive index value of the obtained glass was about 0.5% lower than that of 5in2.

Effects of the Invention As mentioned above, the reaction not involving water of the present invention can be carried out by J:
The manufacturing method for fluorine-containing glass, which is characterized by increasing the fluorine yield by increasing the amount of fluorine, allows the manufacturing process to be configured using equipment with a relatively simple raw material system, and allows for stable synthesis over a long period of time. It is possible to synthesize high-purity fluorine-containing glass that is highly economical, and has a low refractive index and low dispersion due to the inclusion of fluorine in core materials used for special purposes such as cladding materials for optical fibers and optical fibers for infrared transmission. It is highly effective when applied to the production of high-purity fluorine-containing glass used in glass and the like.

Claims (1)

[Claims] (1) A method for synthesizing glass by introducing a raw material for glass synthesis into a flame, reacting the raw material for glass synthesis in the flame to form fine particles, and depositing the formed fine particles on a starting material, the method comprising: The raw material for glass synthesis is composed of 5iC14 and a fluorine-containing gas, and the flame-forming gas is composed of a hydrocarbon gas having a molecular composition element ratio of 110 of 1.0 or less or a gas containing no hydrogen element. Method for manufacturing glass containing glass. <2) The method for producing a fluorine-containing glass according to claim 1, wherein the hydrocarbon gas having a Mij 11/C of 1.0 or less is acetate (6) and the fluorine-containing gas is a fluorocarbon gas. .