JPS62292625A - Production of glass - Google Patents

Abstract

PURPOSE:To produce glass free from bubbles by decompressing the surrounding of sol in the while till sol is allowed to gel and returning the pressure of the surrounding of sol to be ordinary pressure when sol is allowed to nearly gel in a gelation stage of the production of glass by a sol-gel method. CONSTITUTION:After performing the hydrolysis of a metal alkoxide soln., fine powder is added and homogeneous sol is produced by repeating the projection of ultrasonic wave and the stirring thereof. This is introduced into a cylindrical vessel 1 made of polyprene and the vessel is stopped and set on the bearing 3 of a rotating device. The cylindrical vessel 1 is rotated at about 1,000rpm number of revolutions by driving a motor 2 and the surrounding pressure is reduced to about 65mmHg. When the viscosity of sol suddenly rises and sol is allowed to nearly gel, the pressure of the surrounding of sol is returned to the ordinary pressure. After the pressure is returned to the ordinary pressure and about 3min elapse, sol is allowed to gel.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing glass by a sol-gel method.

[Conventional technology]

The conventional sol-gel method for manufacturing glass involves hydrolyzing a metal alkoxide solution and then adding fine powder, as described in Seikan 20672 and Japanese Patent Application No. 58-237577 (Toki et al.). Then, ultrasonic irradiation and stirring were repeated to obtain a homogeneous sol, and the sol was adjusted to pH 1F to form a gel in a certain period of time to obtain a wet gel. After aging this wet gel for several days, it was dried and sintered under a certain temperature and program to vitrify it, yielding high-quality, high-purity glass.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, air is incorporated into the sol in many cases such as addition of fine powder, ultrasonic irradiation, stirring, and pH adjustment. Furthermore, as shown in 20672, when a cylindrical gel is created by rotational gelation, a large amount of air is taken in at the initial stage of rotation. Once these air is taken in, it is difficult to extract it from the sol due to its high viscosity, and many of the small air bubbles remain trapped in the sol and turn into a gel, resulting in some air bubbles in the resulting gel. exists. Even if such a gel is dried and sintered, extremely small bubbles remain on the outside of the plate, which is one of the causes of deteriorating the quality of the resulting glass.

Therefore, the present invention is intended to solve these problems, and its purpose is to eliminate air bubbles contained in the sol,
The purpose is to improve the quality of the glass obtained.

[Means for solving problems]

The glass manufacturing method of the present invention includes a sol solution steel manufacturing process, a gelling process, a gel drying process, and a gel sintering process. During this period, the pressure around the sol is reduced, and the pressure is returned to normal pressure near gelation to cause gelation.

[For production]

In fine powder addition, ultrasonic irradiation, stirring, pH adjustment, etc.
Much air is incorporated into the sol. Among these air, those taken in as large bubbles with a diameter of 1 m1 or more can escape to the outside of the sol due to their buoyancy. However, bubbles with a diameter of 11 or less, especially 0.1-
When the number of bubbles is 1 or less, the viscosity of the sol is high, so the bubbles remain in the sol and turn into a gel. However, by reducing the pressure around the sol as in the present invention, these fine bubbles increase in volume and can be drawn out of the sol. By removing the air bubbles, a gel with very few air bubbles can be obtained by gelling the released sol.0 By reducing the pressure around the surrounding area,
New fine air bubbles are generated in the gel. These bubbles are originally very fine bubbles, or the alcohol in the sol is vaporized due to reduced pressure. However, these bubbles also disappear when the surrounding pressure is returned to normal pressure near the gelation of the sol. Therefore, it is possible to obtain a gel with very few bubbles by reducing the surrounding pressure before gelation and returning to normal pressure near gelation to cause gelation. Furthermore, since some alcohol in the sol is removed by reducing the pressure, it also has the effect of shortening the gelation time and strengthening the gel. However, the pressure around the gel is 601■
It is most effective if it is higher than Hg, and if it is lower than 60mlHg and around 500Hg, the sol will boil.

〔Example〕

The present invention will be described in detail below based on examples.

[Example 1] Ethyl silicate) (Si(○Cz Hs)4) 40
0ml, water 284mj! , 0.02N hydrochloric acid 182 mj
! , 140 g of finely powdered silica was mixed, vigorously stirred, and subjected to ultrasonic irradiation, centrifugation, and filtration to obtain a highly homogeneous sol. This sol contains 0. Add IN ammonia water, adjust the pH value to 4.8, and add 650cc of it to 48Ryuφxs
It was put into a cylindrical container made of polybrene made by Ryu. This container was fitted with a stopper with a five-shaped hole in the center and attached to the rotating device shown in Figure 1. After this, the polyprene cylindrical container was rotated around the tube axis at a rotation speed of 11000 rpm,
The ambient pressure was reduced to 65 mmHg. Further, about 100 cc of the same gel was placed in a disposable cup and the gelation time was determined under reduced pressure. The viscosity of the sol in the disposable cup rose rapidly, and at a point when it seemed to be near gelation, the pressure around the sol was returned to normal pressure. It gelated about 3 minutes after returning to normal pressure.

After this, continue to rotate at LOOQ rpm for 4 hours.Wait until the gel becomes sufficiently hard.After completing 0 rotations, continue to rotate the gel for 5 days.
Aging at 0℃, drying at a constant temperature and program,
When sintered, it was 23.5IIIφX 250 m
A quartz tube of s was obtained. There is 1 air bubble in this tube.
The only ones with a diameter of 0.1 m were present at a rate of 3 x 10 -3 per -.

[Comparative Example 1] Same as Example 1, 400m of ethyl silicate! ,Wed 28
4mm! , around 0.02N hydrochloric acid 182, fine powder silica 1
Mix 40g, stir vigorously, irradiate ultrasound, centrifuge,
Filtration was performed to obtain a highly homogeneous sol. O, I in this sol
Add N ammonia water, p) (adjust the value to 48, and add 650 cc of it to 48 Sodium 1φX 55 Q s
It was placed in a polybrene cylindrical container. This container was rotated around the tube axis at a rotation speed of LOOORPM to cause gelation under normal pressure. After pH adjustment, gelation occurred in about 25 minutes. Thereafter, rotation was continued for 4 hours at 11,000 rpm until the gel became sufficiently solid. After this, the seaweed was sintered in the same manner as in Example 1 to obtain a quartz tube with a diameter of 23.51 mm and a diameter of 250 fl. The number of air bubbles in this tube is 2X per 1d.
There was one with a diameter of 0.5 fl at a ratio of 10-''.

[Example 2] Ethyl silicate (Si(OCz Hs)4) 800
ml, water 569mj! , 0.02N hydrochloric acid 365 mj,
281 g of finely powdered silica was mixed, vigorously stirred, and subjected to ultrasonic irradiation, centrifugation, and filtration to obtain a highly homogeneous sol. This sol contains 0. Add IN ammonia water and adjust the pH value to 4.
8, and 1344m1 of that is a polypropylene container (length 420fix width 32Q+nx depth 80mm)
I put it in. Thereafter, the container was placed under a pressure of 65 nHg to remove air contained in the sol. When the number of bubbles generated in the sol decreased, the surrounding pressure was returned to normal pressure.

After this, the container was allowed to stand still to allow gelation. After aging the wet gel thus obtained at 30°C for 5 days, drying and sintering under a certain program and temperature resulted in *25
A plate-shaped quartz glass of 0 tm x 1571 layers in width x 5 layers in thickness was obtained. In this hypothetical case, only some bubbles with a diameter of 0.1 mm were present at a ratio of 3XIO-' per 1 d.

[Comparative Example 2] A sol obtained in the same manner as in Example 2 was mixed with 0. After adjusting the pH value to 48 with IN ammonia water, 1344 ml of the solution was placed in a polyprene container and gently gelled. 30 days after gelation
After aging at ℃ for 5 days, drying and sintering under a certain program and temperature, the result was 205 tm long x 157 tm wide x
A plate-shaped quartz glass having a thickness of 511 mm was obtained. In this hypothetical case, there were bubbles with a diameter of 0.5 mm at a rate of 2 x 10 -2 cells per liter.

As described above, a glass with few bubbles can be obtained by placing the sol under reduced pressure to remove air bubbles within the gel before gelation, and returning the sol to normal pressure near gelation to allow gelation.

〔Effect of the invention〕

As described above, according to the present invention, the pressure around the sol is reduced until the sol gels, and the pressure is returned to normal pressure near gelation to cause the gelation to occur, so air bubbles are contained in the resulting glass. will be smaller and fewer in number. The glass thus obtained is of very good quality and can be used in a variety of fields, including tubular ones as jacket tubes for optical fibers and furnace core tubes for semiconductors, and plate-shaped ones as mask substrates.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a schematic diagram of a rotating device used in Example 1. 1...Cylindrical container 2...Motor 3...Bearings are as follows.

Claims (1)

[Claims] In the gelling step of the glass manufacturing method, which includes a steelmaking step of the sol solution, a gelling step, a gel drying step, and a sintering step of the gel, the pressure around the sol is reduced until the sol gels, A method for producing glass characterized by gelling by returning the pressure to normal pressure near gelation.