JPH04175291A - Glass manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to optical components such as lenses of projection exposure apparatuses for integrated circuits, TPT substrates for liquid crystal displays, prisms, and beam splitter-1 spectrometers. This invention relates to a method for producing quartz glass and various glasses with excellent optical properties by a sol-gel method.

[Conventional technology]

In the production of glass using the conventional sol-gel method, which uses fine particles of metal alkoxides and metal oxides as main raw materials,
For the purpose of the present invention, the porous gel body in the middle of the sintering process is not treated in a solution, but is immersed in a solution containing other components for the purpose of doping them. It was something.

[Problem to be solved by the invention]

In conventional manufacturing methods, the purity of the resulting glass is poor due to impurities contained in the starting materials and impurities introduced from the outside during the process, and the separation of the hydroxyl groups present inside the kel during the sintering process is poor. As a result, a large amount of hydroxyl groups remain inside the glass, which deteriorates the thermal properties.

Alternatively, the hydroxyl groups may form bubbles and optical properties may deteriorate.

Therefore, an object of the present invention is to provide a method for easily producing extremely high quality glass by providing a method for easily separating impurities, hydroxyl groups, etc. from a gel body.

[Means to solve the problem]

In the method for producing glass by the sol-kel method of the present invention, a liquid sol having a desired glass component composition is prepared using metal alkoxide and metal oxide fine particles as main raw materials, and the liquid sol is placed in a closed container of a desired shape. In a production method in which a wet gel is produced by gelation, and then the wet gel is vitrified by heat treatment such as drying and sintering, during the sintering process, at a stage where the gel body is porous and has not been densified. , characterized in that the gel body is immersed in a hydrochloric acid solution.

[For production]

In the present invention, by immersing a porous gel body in a hydrochloric acid solution, it reacts with the impurity metal (M) and produces metal chloride (M).
MCj is also replaced by chlorine and hydroxyl group in Kel body (
=S 1-0H-miSi-Cg) is produced. The former can be easily separated by heat treatment, and the latter by heat treatment in an oxygen atmosphere.

Therefore, the obtained glass is of high quality with high purity and excellent thermal properties and optical properties.

〔Example〕

Ethyl silicate, ethanol, water, ammonia water (2
9%) were mixed at a molar ratio of 1, 6:4:008, stirred for about 3 hours, and then allowed to stand at room temperature to grow and ripen the particles.

Thereafter, by concentrating under reduced pressure, a silica fine particle dispersion liquid with good dispersibility was prepared.

On the other hand, using ethyl silicate in an amount of 1/4 of the above ethyl silicate, add 0.02 N hydrochloric acid so that the weight ratio is 1:1, and stir for about 2 hours while cooling on ice to obtain a hydrolyzed solution. was prepared.

Here, the pH value of the silica fine particle dispersion liquid was adjusted to 4.5 by adding 2N hydrochloric acid, and then a hydrolyzed solution of ethyl silicate was mixed therein and sufficiently stirred until a homogeneous liquid sol was obtained. After that, 0.2N aqueous ammonia was added to the liquid sol to adjust the pH value to 5°0, and the liquid sol was poured into a cylindrical mold with a diameter of 4Qcm to a height of 10cm.
The container was covered with a lid and allowed to gel in an airtight state. The obtained wet gel was stored in a polypropylene drying container (opening ratio 0°5%).
When dried in a constant temperature dryer kept at about 70℃, the drying was completed in about 3 weeks and the diameter was 28℃.
A cylindrical white gel with a height of 7 cm and a height of 7 cm was obtained. The thus obtained gel body was once heated to 900° C. in an oxygen/nitrogen atmosphere, and various treatments such as acceleration of the condensation reaction, dehydration, removal of residual residues, etc. were performed. After this, the following two types of treatments were performed on each gel.

Treatment 1 The obtained gel body was immersed in a 2N hydrochloric acid solution, left to stand for 12 hours, and then dried at 100°C.

Treatment 2 The obtained gel body was immersed in a 10N hydrochloric acid solution, left to stand for 12 hours, and then dried at 100°C.

Three types of gel bodies, a gel body subjected to the above treatment 1.2 and a gel body not particularly treated, were heated to 1350° C. under reduced pressure or in an oxygen atmosphere to vitrify them. Furthermore, the temperature was raised to 1750° C. in a nitrogen atmosphere, held for 30 minutes, and slowly cooled.

The glass body thus obtained was a highly transparent cylinder with a diameter of 20 cm and a height of 5 cm.

In addition, the physical properties of the obtained glass, such as Vickers hardness and specific gravity, were consistent with those of quartz glass. Furthermore, when the spectral characteristics in the infrared, near-infrared, visible, and ultraviolet regions were measured, differences were observed depending on the presence or absence of treatment. In particular, regarding the light transmittance in the ultraviolet region, no absorption was observed in the case of treatment 1.2, but in the case of no treatment, the wavelength was 250 nm,
There was absorption in the vicinity of 20 Onm and around 20 Onm. Furthermore, the amount of OH groups present inside the glass was calculated from infrared and near-infrared absorption, and the results were as shown in the following table.

Table: Content of OH groups inside glass [Effects of the Invention] As described above, according to the method of the present invention, it is easy to produce a large lump of glass with excellent optical properties.

As a result, it is expected that its application will expand not only to fields where quartz glass has been used up until now, but also to a variety of fields that require particularly high quality, such as IC photomask substrates, optical fiber base materials, and special optical applications. Conceivable.

Moreover, in the sol preparation process, B5Ti, Ge.

Na, Ca5LiSAllXTe, Zr, Ce, Nd,
Since it is possible to add various elements such as Cr, Zn, Mu, etc., it is easy to manufacture various multi-component glasses and new glasses that do not have existing compositions. There are various ways to add these various elements, such as an aqueous solution of a salt of each element, an alkylcoside, etc., or adding fine particles of oxide of each element. You can do it in a suitable manner.

that's all

Claims (1)

[Claims] 1) Prepare a liquid sol with the desired glass component composition using metal alkoxide and metal oxide fine particles as main raw materials, gel the liquid sol in a sealed container of a desired shape to produce a wet gel, and then In a manufacturing method using the sol-gel method in which gel is vitrified by heat treatment such as drying and sintering, during the sintering process, when the gel body is porous and has not yet become dense, the gel body is placed in a hydrochloric acid solution. A method for producing glass, which is characterized by immersion.