JPS63112430A - Production of glass - Google Patents

Abstract

PURPOSE:To obtain a high-quality glass is high yield, by producing a liquid sol mainly from alkyl silicate and ultrafine silica particles, gelatinizing the sol in a closed vessel allowing the shrinkage and drying and sintering the produced gel. CONSTITUTION:Alkyl silicate mixed with ultrafine silica particles and HCl is stirred for 2-3hr to effect the hydrolysis of the alkyl silicate and obtain a liquid sol produced by the decomposition of the ultrafine silica particles and having the composition of the objective glass component. The sol if put into a closed vessel and gelatinized by heating. After maintaining the closed state until the wet gel is shrunk to a linear shrinkage of >=1%, the gel is dried and sintered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing glass by a sol-gel method.

[Conventional technology]

A sol-gel that uses conventional alkyl silicate and ultrafine silica as main raw materials and prepares a sol by mixing ultrafine silica into an acid-catalyzed hydrolysis solution of alkyl silicate to gel, then drying and sintering the sol. In the production of glass by this method, the pH value of the prepared sol was adjusted to about 3 to 6 by dropping a base.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, the sol PHgt1i1M
It is extremely difficult to completely decompose and remove the neutralization reaction products that remain in the dry gel during sintering, as the neutralization reaction products that are mixed in during sintering are gelled and remain in the dried gel. It becomes a blade that generates defects. Therefore, there is a problem in that the load required during sintering to produce high-quality glass becomes extremely large. Furthermore, if the pH value of the sol is not adjusted, the gel strength is low and it breaks during drying and sintering, making it difficult to produce large glasses.

Therefore, the present invention aims to solve these problems.
Stable quality can be achieved if the linear shrinkage rate is 1% or more, and the purpose is to provide a method for manufacturing glass using the sol-gel method that easily produces high-quality glass at a high yield. There it is.

[Means for solving problems]

The method of the present invention involves preparing a liquid sol with a desired glass composition using alkyl silicate and ultrafine silica as main raw materials, gelling the sol, drying and sintering the sol.
A method for manufacturing glass using a gel method is characterized by having the following conditions. (α) The prepared sol is heated in a sealed container to form a gel. (h) After the gelation, the device maintains the airtight state until the reaction progresses and the wet gel shrinks by 1% or more in terms of linear shrinkage rate. It is.

[Effect]

According to the present invention, since the sol PH value is not adjusted, there are no products that cause defects in the glass, and the sintering conditions can be easily set. In addition, since the gel is heated in a sealed state and maintained in this state to some extent, the reaction progresses at an appropriate speed without adjusting the pH value, and the gel strength increases, resulting in drying and sintering. This prevents cracking.

〔Example〕

(1) Commercially available ethyl silicate (5i(oEt)4) 1
52t, α01N HC3t 108t and ultrafine silica (trade name Aerosil 0X50 (Degussa))
") 45Kj' were mixed at the same time and stirred for 2 to 3 hours using a disilver (stirring and dispersion device) to carry out a hydrolysis reaction of ethyl silicate and prepare a sol containing a certain fraction of ultrafine silica. After this, In order to further improve the dispersibility, the sol was irradiated with ultrasonic waves (combined with stirring) for 55 minutes.
It was carried out for ~7 hours. At this time, the shift was performed using ultrasonic irradiation! +/To prevent a rise in temperature, the sol temperature was kept constant by a cooling device.

As a next step, the sol is subjected to centrifugation treatment (5000 rpm,
0 m) was added.

After this, the sol was filtered and the size 30X50X15 (c
rn) polypropylene containers each with 1000? , 25
It was injected into 0 pieces and sealed in 7 bottles. these,
50 pieces each, 20℃ each.

The mixture was placed in a constant temperature bath at 30°C, 40°C, 50°C, and 60°C to form a gel. After gelling, put a lid on the 5-mouth opening and the drying speed is l! ! The material was changed to one that could be knotted and dried at 60°C. Although there was some variation, the drying was completed in about 10 days and 21
．． OX 2t 0口口(of).

A dry gel of 350 flW was obtained.Table 1 shows the yield.

Table 1. Drying yield Table 2 also shows the shrinkage rate at each temperature when transferring to the drying step.

Next, the dried gel obtained here was put into a sintering furnace, and heated and sintered to obtain a transparent glass body at 1280°C. The size of this glass is %15. ．． OX1! LOXO,45[:α
], and the weight was 280 Pli degrees.

When the glass obtained as described above was observed using an optical microscope or a condensing lamp, no defects were observed in the glass and it was found to be in very good condition. Also,
The physical property analysis results for these glasses, including Vickers hardness, specific gravity, coefficient of thermal expansion, infrared absorption spectrum, near-infrared absorption spectrum, and refractive index, all matched those of fused silica glass.

〔Effect of the invention〕

As shown in the examples above, according to the method of the present invention,
It is possible to produce a dry gel at a high yield without adjusting the pH value of the sol. Furthermore, since there is no influence on quality from neutralization products, high-quality glass can be produced using a simple sintering method. Therefore, mass production of high quality glass becomes easy.

Furthermore, the quartz glass produced by the present invention is less expensive than other production methods (melting method, OVD method, etc.),
Because high-quality glass can be manufactured easily, it is being applied not only in fields where quartz glass has been used up until now, but also in various fields such as photomask substrates for industrial C and base materials for optical fibers. think. Furthermore, by mixing different types of elements in a sol state, it is easy to produce multi-component glasses with various properties.

Claims (1)

[Claims] (1) A method for producing glass by a sol-gel method in which a liquid sol with a desired glass component composition is prepared using alkyl silicate and ultrafine silica as main raw materials, the sol is gelled, and then dried and sintered. A method for producing glass, characterized by having the following conditions. a) Heat the prepared sol in a sealed container to gel it. b) After the gelation, the sealed state is maintained until the reaction proceeds and the wet gel shrinks by 1% or more in terms of linear shrinkage rate.