JPS60215531A - Production of quartz glass - Google Patents

Abstract

PURPOSE:To prepare a high-quality quartz glass at a low cost, improving the yield of dry gel, by using a specific sol solution as a raw material solution in the sol-gel process for the production of quartz glass. CONSTITUTION:Ethyl silicate is hydrolyzed under the condition of Si(OC2H5)4: H2O:HCl=1:2:0.072 (mol ratio) to obtain a homogeneous transparent solution. The solution is mixed with water of an amount necessary for the preparation of a sol, dispersed with fine silica powder, and added with ammonia water to obtain a sol solution of about 3-5pH. The obtained sol solution is charged in an arbitrary vessel, gelatinized, dried, and calcined according to a prescribed heating program to obtain a transparent quartz glass.

Description

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

, c: Prior art] In recent years, quartz glass has been improved by reducing the concentration of impurities such as copper and boron to 0.
．． Products with a high purity of less than 1 ppm are manufactured, and are widely used in crucibles and boards in the manufacturing process of germanium, silicon, and other semiconductors, and in the core tube of diffusion furnaces.They are also used in physical and chemical equipment, cells for optical measurement, etc. 1-1 is also commonly used, and high-quality and improved products with less hydroxyl base Ill and excellent optical homogeneity have been developed and have been used for various optical applications, especially optical Ill. ! There is a note on the stone glass fiber used for the material. Currently, quartz glass tar, which has a wide range of uses, is manufactured using the following method: 1) Cleaning and melting with natural quartz 2) High purity 81
0 t4 Mayu is a method of manufacturing 8103 using G i H4 as a raw material 3) A method of melting natural silica sand (silica glass containing bubbles is obtained) However, the above method of manufacturing chair n also requires high raw material costs. Things,
The 12-metre manufacturing cost is high, such as the need for high-temperature treatment, and quartz glass is very expensive.

Therefore, as an inexpensive manufacturing method for high-quality quartz glass, sol-based
The gel method has attracted attention, and research on the production of quartz glass using this method has been widely conducted in various places, but at present it has not been put into practical use due to various problems. The following method has been devised as a method for producing quartz glass using the sol-gel method. That is, ethyl silicate) (Si(002H5)4) is mixed with a hydrochloric acid solution to prepare a hydrolyzed solution of ethyl silicate. Adjustment of.

Add heat treatment and make it into silica gel. The resulting lumps of silica gel are placed in a furnace and sintered according to a predetermined program to form quartz glass.One of the problems with this method is that it is necessary to improve the yield of dry gel production. Let's do it.

The silica reaction products caused by adjusting the sol pH value by dropping aqueous ammonia etc. have an adverse effect on sintering, resulting in the presence of various defects (bubbles, etc.) in the quartz glass.
One of the reasons is that it is difficult to obtain homogeneous glass.

〔the purpose〕

The purpose of the present invention is to solve the above-mentioned problems, and to provide a method for producing transparent homogeneous quartz glass by minimizing the amount of neutralization reaction products produced during sub-adjustment of the pH value. It is to be.

〔overview〕

The hydrolysis reaction of ethyl silicate ([31(002H5)4) is carried out using raw material composition 5i(002H,)4: T(,
O: mouth = 1:2: (1072 (molization)),
After mixing and stirring until the solution becomes transparent and homogeneous,
Add and mix H2O, which is necessary for subsequent sol preparation, and further add fine powder silica. Adjust the sol by dispersing it in the solution, and raise the sol pHI to about 50 to 5.0 with ammonia water. This is a method of gelling, drying, and sintering the dried gel to form quartz glass. If this method is used, the neutralization reaction produced by adjusting the pH value will be reduced to 40 cm compared to the conventional method. below,
The contents of the present invention will be explained in more detail according to the first embodiment.

〔Example〕

Commercially available ethyl silicate 5i(O[!;t)4264-
When mixed with 0.02NHO6Ai2 and stirred vigorously, 172,8 m7 of H2O was added to the solution, which became an apparently homogeneous and transparent solution in about 1 hour. Gradually added to the rice, the amount of rice became slightly cloudy, but after stirring for a while, the hydrolyzed solution became homogeneous and transparent. However, the aforementioned raw material (Si
(Offit) 4264go, α02NHO445,
2nt, H20172, 8ml) at the same time, no reaction occurred and the phases separated. Finely powdered silica (trade name: Aθrosil) is added to the hydrolyzed solution.
oxs.

(DiguSSa)) 901F was added with stirring. After the addition, in order to further improve the dispersibility of the fine powder, the mixture was stirred for 6 hours and irradiated with ultrasonic waves for 3 hours, then centrifuged (1500F, 10ml) and (LIN) aqueous ammonia was added dropwise to adjust the pH value of the sol. Approximately 4.0 Vc L,
friend. (1 entertainment order is irrelevant) Filter the sol (200me
sh filter) and a polypropylene container (27X
22X1t5cm) Pour K, fit it, and let it gel in a sealed state. After leaving it in this state for 2 to 3 days, replace the lid with one that can adjust the drying speed and put it in the dryer for 30 minutes.
Raise the temperature from ℃ to 60℃ at a heating rate of 5-3℃7nrK, and then increase the temperature to 60℃
After holding and drying for about 5 days, it reached a size of 1115 mm.
A plate-shaped dry gel of X14.5X[L6cIn was obtained. This dry gel was placed in a sintering furnace, and the heating rate was 1801117n.
The glass was heated and sintered at 1260° C. to obtain a transparent quartz glass having a size of 150×IQ, OXo, and 4z.

When this glass was inspected with an optical microscope, compared to the previous case where there were many HCl particles in the raw material, the size and number of foreign objects (such as air bubbles) present in the glass were considerably smaller, and there were no foreign objects larger than 10 μm. There wasn't. The results of various physical property analyzes regarding this glass are that it has a Vickers hardness of 800.
V4/J, specific gravity 2.2, infrared absorption spectrum, near-infrared absorption spectrum, and refractive index, etc., are consistent with fused silica glass, and the 9 quartz glass obtained here is a very high quality silica glass. It's clearly Natsu's skin.

〔effect〕

In this way, the quartz glass produced by the present invention has great advantages such as being able to be produced at a lower cost than the conventional method (melting method), and is of course used in fields where quartz glass has been used up until now. In particular, since quartz glass of good quality can be easily manufactured in Kmm,
We believe that its applications, including optical uses, will continue to expand over a wide range of areas.

that's all Applicant: Suwa Seikosha Co., Ltd. Agent: Patent Attorney Mogami 7-

Claims (1)

[Claims] Alkyl silicate and finely powdered silica are used as raw materials.
In the silica glass manufacturing method using the sol-gel method, the alkyl silicate is ethyl silicate (ethyl silicate) (
5t(oa2Hs)4), this hydrolysis reaction is proceeded with % of the total stoichiometric amount of H20 (HO/!, solution),
Thereafter, a method for producing quartz glass is characterized in that a hole 20 necessary for sol adjustment is added.