JPS61242919A - Production of quartz glass - Google Patents

Abstract

PURPOSE:In a low-temperature synthesis method by sol-gel process using ultrafine powder silica as a raw material, to obtain quartz glass having small heat distortion and high heat resistance, by making >=1ppm aluminum content in the raw material. CONSTITUTION:Ultrafine powder silica containing >=1ppm aluminum is used as a raw material. This raw material are processed with water and a solvent such as an alcohol, etc., to form sol. Then, this sol is gelatinized, contracted and dried under a proper condition to give dry gel, which is calcined. Consequently, quartz glass having small heat distortion at high temperature and high heat resistance is obtained.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing quartz glass using a sol-gel method, and more particularly to a method for producing quartz glass with high heat resistance. [Prior art] The conventional sol-gel method for synthesizing quartz glass uses high-purity alkyl silicate or high-purity ultrafine powder silica as raw materials, forms a sol with a solvent such as water or alcohol, and produces a gel. The gel is dried by shrinkage under appropriate conditions to form a dry gel. The dry gel was sintered under appropriate conditions to produce transparent quartz glass. [Problems to be Solved by the Invention] However, the above-mentioned prior art has the following drawbacks. When silica glass is used with a height of 1, thermal deformation such as warping or bending is likely to occur, which is a major problem when applied to various precision products such as thin film transistors. The present invention is intended to solve these problems, and its purpose is to provide a method for manufacturing quartz glass that is less susceptible to thermal deformation at high temperatures. [Means for Solving the Problems] The method for producing quartz glass of the present invention is a low-temperature synthesis method of quartz glass by a sol-gel method using at least ultrafine powdered silica as a raw material. The content is 1. ppm or more. [Function] According to the above configuration of the present invention, aluminum atoms are present in the quartz glass, and the presence of a trace amount of aluminum atoms improves the heat resistance of the quartz glass. [Example] Hereinafter, the present invention will be explained in detail with reference to Examples. 208 tons of purified commercially available silicon ethoxide

[1 mole]
A, 01N hydrochloric acid 280- was added to the mixture, and the mixture was vigorously stirred for hydrolysis. Next, ultrafine powdered silica with an aluminum content of t 1.5 ppm (surface area 50
m”/f of Aerosil 0X50) (1.5 mol) was added while stirring, and ultrasonic vibration was applied. Furthermore, after centrifuging, remove any lumps using an IC, and then add cL1.
A specified amount of ammonia water was added dropwise to adjust the PR value to 4.0. Next, this sol was charged into a polypropylene box-shaped container (W30XD30XH1, Oa++) so that the height was 13. The mixture was sealed tightly and allowed to stand at 20°C to form a gel, and was then stored overnight. Next, the lid of the container was changed to one with an opening ratio of 18%, the temperature was raised from room temperature to 60°C, and the lid was dried at this temperature for 10 days. A stable dry gel that did not crack even when left at room temperature was obtained. Then p1. a Transparent quartz glass was obtained by heating and sintering to 00°C. When the purity of this quartz glass is measured, it is found that 4-2 ppm of aluminum is present, and when the raw material is ultrafine powdered silica, which has a conventional aluminum content of -o' ppm, the aluminum content in quartz glass is is o ppm, so it can be seen that the aluminum content of the quartz glass according to this example is increased. In addition, the quartz glass obtained in this example and the quartz glass with an aluminum content of Oppm obtained by the conventional method were heated at +0O
1X word OX1.2. It was machined and polished to a rough shape, supported as shown in Figure 1, and placed in an electric furnace. When heat treated at 1150°C for 5 hours, the amount of deflection was as shown in Table 1. [Effects of the Invention] As stated, according to the invention, aluminum is 1.
When silica glass is manufactured using ultrafine powdered silica containing more than ppm of silica as a raw material, the amount of thermal deformation at high temperatures is small.
Can produce quartz glass with high heat resistance.

[Brief explanation of drawings]

FIG. 19 is a schematic diagram defining the heat resistance of quartz glass. Figure 1

Claims (1)

[Claims] A method for producing quartz glass at a low temperature by a sol-gel method using at least ultrafine powdered silica as a raw material, characterized in that the aluminum content of the ultrafine powdered silica as a raw material is 1 ppm or more.