JPH0825754B2 - Glass manufacturing method - Google Patents

Description

The present invention relates to a method for producing glass by a sol-gel method.

[Conventional technology]

Conventionally, in the production of glass by the sol-gel method, usually, an alkyl silicate monomer is used as a raw material, which is hydrolyzed by an acidic or basic catalyst to prepare a sol, which is then gelled, dried and baked. It was intended to make glass by binding.

[Problems to be solved by the invention]

However, in the above-mentioned conventional technique, it is very difficult to produce a large gel, and cracks occur during shrinkage drying and sintering. Although this problem has been considerably improved by adding ultrafine particle silica to the sol, it has a problem that it takes a long time to dry and is inefficient.

Therefore, the present invention solves such a problem, and an object of the present invention is to provide a method for producing a large glass by a sol-gel method with high yield and in a short time.

[Means for Solving Problems] As a main material of alkyl silicate, a sol is prepared,
In the production of glass by the sol-gel method of gelling this to prepare a wet gel, then drying and sintering the wet gel, at least as a raw material alkyl silicate, a dimer to octamer alkyl polysilicate oligomer and It is characterized by using ultrafine particle silica.

[Action]

According to the present invention, since a multimeric alkyl silicate is used as a starting material, this is the minimum unit of the skeleton of the gel structure, and it is easy to form a porous structure as compared with the case where a normal monomer is the minimum unit. Further, by adding ultrafine particle silica, the effective silica concentration in the sol is increased, so that cracks are less likely to occur during drying and sintering after gelation, and it is possible to produce a large glass in a short period of time. It is a thing.

〔Example〕

Example 1 Commercially available ethyl silicate (trade name: ethyl silicate
40 (Colcoat Co., Ltd. 4-6-mer) 1,000 ml, ethyl alcohol 1,500 ml, water 200 ml and ultrafine silica
600 g was mixed and stirred and irradiated with ultrasonic waves to obtain a uniform sol solution. After this, 5 ml of 1N ammonia water
After dripping and stirring for 10 minutes, each 900 ml size 30 × 30
The mixture was poured into three × 15 [cm] square containers, covered with a lid, and sealed to gel in about 30 minutes. After that, after leaving it in a sealed state for one day and night, the lid was made to have a porosity of 3%, put into a dryer, and heated from room temperature to 70% in 1 hour.
After that, the temperature was maintained at 70 ° C and the drying was completed in about 5 days. The dry gel prepared here has a size of 27 × 27 × 0.9 (c
m], the weight was about 400 g, and the appearance was good without cracks.

These 3 dried gels were put into a sintering furnace and the temperature was 60 ℃ / h.
When heat-sintered at three heating rates of r, 180 ° C / hr, and 300 ° C / hr, 1,200
Transparent vitrification was performed at about ℃, 1220 ℃ and 1260 ℃. The size of the glass was 16.8 × 16.8 × 0.55 [cm] and the weight was about 330 g, and it was a perfect body with no cracks or cracks during sintering. The results of various physical properties analysis on the glass produced in this manner, Vickers hardness, specific gravity, thermal expansion coefficient, infrared absorption spectrum, near-infrared absorption spectrum, in agreement with fused silica glass such as refractive index, even in the purity analysis,
Impurity elements above 1 ppm were not detected.

Example 2 Commercially available ethyl silicate (trade name: ethyl silicate
40 (Colcoat Co., Ltd. 4-6-mer) 1,000 ml, ethyl alcohol 1,500 ml, water 200 ml and ultrafine silica
600 g was mixed and stirred and irradiated with ultrasonic waves to obtain a uniform sol solution. After this, 20 ml of 1N ammonia water
After dripping and stirring for 10 minutes, each 900 ml size 30 × 30
The mixture was poured into three × 15 [cm] square containers, covered with a lid, and sealed to gel in about 10 minutes. After that, after leaving it in a sealed state for one day and night, the lid was made to have an opening ratio of 4%, put into a dryer, and heated from room temperature in 1 hour.
The temperature was raised to 70 ° C., and then maintained at 70 ° C., and the drying was completed in about 3 days. The dry gel produced here has a size of 27.6 × 27.6 ×
It was 0.92 [cm] and weighed about 400 g, and was good in appearance with no cracks.

These 3 dried gels were put into a sintering furnace, and 60 ℃ / hr, 1
When heat-sintered at three heating rates of 80 ° C / hr and 300 ° C / hr, 1220 ° C, 1250 for each heating rate.
It became a transparent glass at about 1285 ℃. The size of the glass was 16.8 × 16.8 × 0.55 [cm], and the weight was about 330 g, and it was a perfect body with no cracks or cracks during sintering.

The results of various physical properties analysis on the glass produced in this manner, Vickers hardness, specific gravity, thermal expansion coefficient, infrared absorption spectrum, near-infrared absorption spectrum, in agreement with fused silica glass such as refractive index, even in the purity analysis, Impurity elements above 1 ppm were not detected.

〔The invention's effect〕

In this way, the quartz glass produced according to the present invention is significantly less likely to crack during drying and sintering after gelation, and a large glass can be produced with a high yield in a short time, as compared with the conventional sol-gel method. It will be. Therefore, it will be applied not only in fields where quartz glass has been used until now, but also in various applications such as photomask substrates for ICs and base materials for optical fibers.

Furthermore, at the time of sol preparation, Al, Ti, Ge, Na, Ca, Mg, Li,
By adding a certain amount of elements such as Te, it is easy to produce multi-component high-quality glass with various characteristics.

Further, quartz glass can be manufactured at a lower cost than other manufacturing methods (melting method, CVD method, etc.).

Claims (1)

[Claims] 1. A method for producing glass by a sol-gel method in which a sol is prepared from an alkyl silicate as a main raw material, the sol is gelled to prepare a wet gel, and the wet gel is dried and sintered. As a raw material, at least a raw material alkyl silicate, a dimer to octamer alkyl polysilicate oligomer and ultrafine particle silica are used.