JPS63147836A - Production of quartz glass - Google Patents

Abstract

PURPOSE:To obtain quartz glass which is free from air bubbles and is optically excellent by subjecting a dry gel to an atm. pressure heat treatment then holding the same for a specified period in a vacuum atmosphere at a specific temp. at the time of producing the quartz glass by a sol-gel method. CONSTITUTION:Metal alkoxide (e.g.; ethyl silicate) is hydrolyzed to produce a sol and after the sol is geled, the gel is dried to produce the dry gel. The dry gel is put into an electric furnace and while air is blown thereto, the gel is heated to about <=1,000 deg.C by which the sintered gel is produced. The sintered gel obtd. in such a manner is put into a high-temp. vacuum furnace and is held for the specified period at 1,000-1,400 deg.C in the vacuum atmosphere; thereafter, the gel is allowed to cool. The non-effective components such as moisture and org. material remaining in the gel are thereby entirely diffused and removed. The colorless transparent quartz glass which does not contain air bubbles, moistures, etc., is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to the production of quartz glass by the Sol-Glu method.

[Conventional technology]

Conventionally, using gold maple alkoxide as the main raw material, l'l"Fy, shattered glass, or glass precursor Fy was produced by the sol-gel method.
In the method for producing quartz glass in which the glass precursor is heated to t- and held for a certain period of time, the dry gel as a glass precursor is heated from room temperature to 14 oooes at normal pressure and held for a certain period of time.

[Problem that the invention seeks to solve]

However, when dry gel is heated and held for a certain period of time, moisture, organic matter, etc. remaining in the dry gel are constantly expelled in each tautomer, but with normal pressure treatment, these so-called glass The problem is that the pores become closed without being able to fully discharge the ineffective ingredients, and when heated and held further, a foaming phenomenon occurs due to vaporization of these ingredients.

Therefore, the present invention aims to solve these problems.
The purpose is to provide a glass product that does not cause these foaming phenomena.

[Means for solving problems]

In the production of glass made by the sol-gel method using metal alkoxide as the main raw material, or quartz glass in which the glass precursor is heated and held for a certain period of time, dry gel'& as the glass precursor is used between 1000°C and 1400°C. , which is characterized by being held in a vacuum atmosphere for a certain period of time. As a result, it is possible to eliminate the one-foaming phenomenon that has hitherto been considered a problem, and to provide high-quality glass, which is the desired product.

[Effect]

When the sol becomes a gel and is heated.

At each temperature, moisture, organic substances, etc. remaining inside the gel are diffused and removed. As a guideline for the amount, ωCIl1
The weight ratio of the glass of the market product to the weight of the dry gel weighed in a day is between 0.85 and 0.9;
Thousands of inactive ingredients will be diffused and removed during the heat treatment. When heat-treated to about 1,400°C under normal pressure, it takes a considerable amount of time to diffuse the non-active ingredients above 1 (lfi), but even in this case, there is no chance that they will remain inside. , a phenomenon of vaporization → foaming occurs. By treating substances that cannot be diffused under normal pressure in a vacuum atmosphere, inactive components can be forcedly diffused and removed efficiently. Since the dry gel contains a considerable amount of water, it is preferable to heat the dry gel in advance at about 800° C. to 1000° C. under normal pressure in order to prevent the performance of the X-air pump from decreasing.

The effect is further enhanced by creating a vacuum atmosphere in the subsequent stage of diffusion and removal of non-effective ingredients due to large shrinkage. In this way, heat treatment is performed under a vacuum atmosphere.

This not only improves the quality of the final product, glass, but also has an effect on processing capacity (reducing processing time).

[Implementation mJ] Ethyl silicate 1 (lA) and 8k of a 0.005N hydrochloric acid aqueous solution were mixed and stirred to obtain a colorless and transparent homogeneous aqueous solution.

Soconi, ultrafine powder silica (AavosiAOX-50)
2.5+'J' was gradually added, and while stirring was continued and the total temperature of the dispersion was kept at 5° C., 2.41 H'l of ultrasonic waves were irradiated for 3 hours to obtain a sufficiently uniform dispersion. Centrifuge this dispersion.

After treatment at 1500 Ck for 10 minutes, the supernatant was passed through a 1 μ filter, and the pH of the resulting dispersion was
0.1N ammonia water to make it 4.0? il[k
Added. Adjusted Sol 1! All-polyethylene container (
The mixture was poured into a chamber (300 m x 300 m x 150 U), sealed, and kept in a room at room temperature for one day and night.

The next day, holes were made in the polyethylene container with a porosity of 0.5%, and the container was placed in a constant temperature bath at 60°C and dried for 141 days.
A white plate-like dry gel with a size of m' and a weight of 340.23 tons was created. This dry gel was placed in a quartz glass box and placed in an electric furnace, and heated while blowing air through a 0.2μ filter.
The temperature was maintained at 00°C, 900°C, and 1000°C for 2 hours each. The temperature increase rate was ω°C/hour. This was left to cool in the furnace and then taken out.

A white plate-shaped sintered gel with a size of 1921IJX 192m x 5.6m and a weight of 305.26f was obtained.

This sintered gel is placed in a high-temperature vacuum furnace, and a diffusion pump is used to
The mixture was heated while maintaining the furnace pressure at t-111"" to 10-' torr, and was held at 1000°C, 1200°C, and 1400°C for heating periods, respectively. After this was left to cool inside the entire furnace.

When I took it out, it was 154 Dragon X 15411 JX 5.
A colorless and transparent quartz glass having a size of 1 g' and a weight of 297.729 was obtained.

After optically polishing this to 127 mg
It was 65wt.

[Comparative example]

The sol prepared in the practical process was similarly placed in a polyethylene container (300aa x 30Chx x 150su).
After pouring KIA and drying in the same manner as in Example 1, a white root-like dry gel with a size of 20/w x 20/ryu x 5.8 ma' and a weight of 335.13P was obtained. This dry gel was placed in a quartz glass box and placed in an electric furnace.

While blowing air through a 0.2μ filter, it was heated and held at 300°C, 900°C, and 1000°C for 2 hours each. The temperature increase rate was set at ω°C/hour.

When I let it all cool inside the furnace and took it out, it was 191mm.
192m x 5, 5u' size and weight 298
．． A white root-like sintered gel of 569 was obtained. This is done in a graphite heating furnace.

Heated in nitrogen atmosphere, 1000℃, 1200℃, 1
Each was held at 400° C. for I minutes. After this was left to cool inside the entire furnace.

When I took it out, it was 154 inches x 154IIJIX 4
．． A colorless and transparent quartz glass having a size of 93IIJ and a single thickness of 296.51P was obtained.

This is t” 127ga x 127m x 2.7+w
After optical polishing.

When 10.000 Jhz light was applied in a dark room, numerous light spots were seen, and when observed with a microscope, the light spots were bubbles of about 100 microns in 10 to 50 microns. Further, when the moisture content was measured, it was found to be %0, 1'163wt.

〔Effect of the invention〕

Claims (1)

[Claims] In the production of glass made by the sol-gel method using metal alkoxide as the main raw material, or quartz glass in which a glass precursor is heated and held for a certain period of time, dry gel as a glass precursor is heated between 1000°C and 1400°C. A method for producing quartz glass characterized by holding it in a vacuum atmosphere for a certain period of time.