JPS60171227A - Manufacture of quartz glass - Google Patents

Abstract

PURPOSE:To mix efficiently the sols, and to manufacture the high-purity quartz glass by hydrolyzing alkyl silicate, then injecting the hydrolysate into a hermetical vessel contg. ultrafine silica powder, and agitating and mixing with strong shearing force. CONSTITUTION:An alkyl silicate such as ethyl silicate is hydrolyzed by using hydrochloric acid, etc., and the hydrolysate is charged through a funnel 4 into an agitating vessel 1a which is hermetically closed with a cover 1b and contains previously weighed silica powder 3 in the low-temp. synthetic method of quartz glass with the sol-gel method by using alkyl silicate and ultrafine silica powder as the starting materials. The contents are then agitated with the strong shearing force by rotating a dissolver blade 2, and a homogeneous sol is obtained without the inclusion of impurities and dispersion of ultrafine silica powder. The pH of the sol is subsequently regulated, and the sol is dried to obtain the dried sol which is further heated to obtain the high-quality quartz glass in high yield.

Description

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

[Prior art]

Quartz glass began to be used in crucibles, boards, diffusion furnaces, etc. during the IC manufacturing process, and its usefulness was recognized, and with the development of products with fewer hydroxyl groups and better optical uniformity, BACKGROUND OF THE INVENTION Quartz glass fibers have come to be used for various optical applications, and quartz glass fibers for optical communications have recently attracted attention.

As described above, quartz glass is used in various fields, and the scope of its use is expanding. However, the production cost of quartz glass is high, which is a problem.A sol-gel method has been attempted as a method for producing high-quality quartz glass at low cost.

In order to obtain large-sized quartz glass with good yield using the sol-gel method, ultrafine powdered silica is gradually added to a sol prepared by hydrolyzing 1-alkyl oxide, and the pH is further increased to 3.
There is a method of drying and sintering at 50 to 90°C after adjusting the temperature to 60°C. This solution simultaneously solved the problem of cracking during dry gel production and the problem of cracking and cranking during sintering, and it became possible to manufacture quite large quartz glass (4 [mm hφ or more)] at low cost.◇ Sol mixture The method of gradually adding ultrafine powdered silica and stirring is intended to improve dispersion, and is designed to keep the sol in a nearly homogeneous state at all times and allow for easy mixing below a certain viscosity. 〇However, when the amount of processing is large, the conventional method has to measure the warping force of ultrafine powder into small portions and move them through the atmosphere, resulting in low work efficiency, contamination of impurities, and problems with ultrafine powder silica. Disadvantages such as discreteness can no longer be ignored and have become a serious problem.

〔the purpose〕

The present invention solves these problems and aims to provide a method for efficiently mixing a sol while preventing the incorporation of impurities and the dispersion of ultrafine powdered silica. [Summary] The quartz glass of the present invention The manufacturing method is a low-temperature synthesis method of quartz glass by the sol-gel method using at least alkyl silicate and ultrafine powder silica as raw materials, and after hydrolyzing the alkyl silicate, ultrafine powder silica is measured out in advance. The present invention is characterized in that it is poured into a container and mixed by stirring with strong shearing force. [Examples] The present invention will be described in detail below based on Examples.

Ethyl silicate 8.8L and 0.05N hydrochloric acid aqueous solution 7
．． 2 Fi was vigorously stirred to obtain a colorless and transparent homogeneous solution 0 In a separate 502 container, ultrafine silica powder (A@r
os il 0X-50) 3'F was weighed, a lid was placed, and the above-mentioned ethyl silicate hydrolysis solution was injected through the hole provided in the lid using a funnel.

With the lid closed, the Disilver blade was rotated at a rotational speed of 80 Or, plm for 30 minutes to obtain a uniform mixed sol. The rotational speed was lowered to 40°r, pom, and stirring was continued for an additional 2 hours to sufficiently disperse the ultrafine silica powder.

The obtained sol had a viscosity of 50 cp (at 25° C.) and an average particle size of 0.22 μm, and exhibited exactly the same physical properties as the sol obtained by the conventional method of gradually adding ultrafine silica powder.

After adjusting the pH of this sol to 4.5 using an ammonia aqueous solution, it was transferred to a container with an inner diameter of 20 cm for 30 hours and heated at 60°C.
A dry gel with a diameter of 14 cm was obtained. When the glass was further heated to 1250°C at a heating rate of 180°C/hr, quartz glass with a diameter of 10c++ was produced. The same experiment was repeated 10 times, but no difference was observed in terms of quality and yield compared to the conventional method.

When the produced quartz glass was treated with heptazic acid and its purity was measured by chemical analysis (atomic absorption 9 emission), it was found that the impurity concentration was extremely high purity with an impurity concentration of 1 oppm or less.

〔effect〕

As described above, according to the present invention, in the low-temperature synthesis method of quartz glass by the sol-gel method using at least alkyl silicate and ultrafine powder silica as raw materials, after hydrolyzing the alkyl silicate, ultrafine powder silica is The sol is measured and poured into a closed container, and stirred with strong shearing force to prevent the contamination of impurities and the dispersion of the ultrafine powdered silica and to efficiently mix the sol.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the stirring device of the present invention. In this state, the hydrolyzed solution is injected through the funnel, and then the funnel is removed and the funnel is sealed, followed by stirring and mixing. 1a... Stirring container 1b... Stirring container lid 2... Disilver blade 3...
Ultrafine powder silica 4...Roto and above Applicant Suwa Seikosha Co., Ltd. Agent Patent attorney Tsutomu Mogami

Claims (1)

[Claims] In a low-temperature synthesis method of quartz glass using a sol-gel method using a small amount of tomoalkyl silicate and ultrafine powder silica as raw materials, after hydrolyzing the alkyl silicate, the warping force of the ultrafine powder is measured in advance and poured into a sealed container. , a method for producing quartz glass characterized by mixing by stirring with strong shearing force.