JPS62230630A - Production of quarts glass - Google Patents

Abstract

PURPOSE:To prevent generation of cracks in drying stage, to improve the yield and to facilitate the production of a large-sized thin glass plate or thick-walled glass, by drying a gel in a drying vessel in a state inclined from horizontal plane. CONSTITUTION:In the production of glass by sol-gel method, the drying of gel is carried out by the following method. A vessel 2 containing a gel 1 is put into a drying chamber 4 in a state inclined from horizontal plane so as to equalize the component force along the direction of movement caused by the shrinkage of the gel to the component force of the own weight of the gel along the contraction movement plane and the gel is dried in the state. The vessel 2 is provided with holes 3 to allow the flow of water separated from the gel 1 to the bottom surface of the drying chamber 4. The contraction movement of the gel in drying is facilitated by the aid of the component force of the own weight of the gel along the contraction movement plane, the generation of cracks in drying can be prevented and a large-sized thin glass or a thick- walled glass can be easily produced.

Description

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

[Conventional technology]

The conventional sol-gel method for producing quartz glass is
As in Gusho 58-237577 and Catechism 422515, both thin gel and thick gel were dried in a horizontal state, and the shrinkage direction and gravity direction of the gel were perpendicular to each other.

[Problem that the invention seeks to solve]

However, the above-mentioned technique has a problem in that both thin glass and thick glass are easily broken when drying.

In the case of thin plate glass, it is easy to break when drying a large area of gel, and in the case of thick glass, it is easy to break when the thickness is increased.

Therefore, the present invention is intended to solve these problems, and its purpose is to prevent cracking during drying and improve yield.[Means for solving the problems] The method for producing quartz glass includes a step of preparing a sol solution, a gelling step, a step of drying the gel, and a step of sintering the gel.
The gel is dried in a drying container by arranging it from a horizontal plane so that the moving direction due to gel contraction and the component force of the gel's own weight in the direction of the shrinking plane are in the same direction. Effect] According to the structure of the present invention, the shrinkage movement of the gel during drying is easily carried out by the component force of the gel's own weight in the direction of the shrinkage movement surface, and cracking during drying can be prevented.

[Example 1] An aqueous solution prepared by adding 18 Wi of hydrochloric acid to 9.5 t of purified commercially available ethyl silicate and 18 t of pure water was vigorously stirred to obtain a colorless and transparent homogeneous solution. Ultrafine powdered silica (trade name Aerosil oxso, Degussa Corporation) 6~ was gradually added thereto and thoroughly stirred. Further, this sol solution was irradiated with ultrasonic waves for 5 hours to ensure the dispersion of the ultrafine powdered silica. A centrifugal force of 1500G was applied to the sol solution for 15 minutes,
Clumps in the sol solution were removed to obtain a highly homogeneous sol solution.

The sol solution was adjusted to pH5.0 with 0.1N ammonia water.
After preparing the polypropylene container (width 20 mm x
20LMX (height: 10 ts) to a depth of 91 cm, the mixture was covered with a lid, and left to gel. The mixture was allowed to stand and mature in a constant temperature room at 50°C for 3 days. Transfer the gel (2) to a polypropylene container (2) with several holes (2) cut in the edges and sides as shown in Fig. The container ■ containing the gel body ■ was placed at an angle.The hole ■ made in the container ■ was used to separate the water from the gel body ■, and the gel body When ■ is placed tilted inside the drying container ■, the separation water will not accumulate in the container ■ but will flow out onto the bottom of the container ■, so that the gel body ■ will be immersed in the separation water during the drying process. I tried to avoid this.

A lid (2) with a porosity of 1.2% was placed on the drying container (2) containing the gel body (2), and the container was dried in a 55c drying room. It took about two months to complete the drying process. The resulting dry gel was 14.5 cm wide x 14.5 cm wide x 5 cm high.

The dry gel was placed in a gas AM furnace and heated at 30°C/hr.
The temperature was raised to qaac at a rate of . Pure helium gas was started to flow into the furnace from 900°C at a flow rate of 1 t/min, and the temperature was increased to 1500°C at a rate of 60°C/hr and held at 1500°C for 3 hours.

The obtained quartz glass is @ 1 a 5 ts x j
[It was a size of L51'ffX thickness 4.8 squares.

[Example 2] Using the sol #j solution shown in Example 1, a gel body (1011) of the same type as in Example 1 was prepared.The gel body (1011) was placed in a drying container (4) as shown in Fig. 3. The container (■) was housed at an angle so that the contraction and movement of the gel was assisted by the component force of the gel's own weight in the direction of the contraction movement surface, allowing the gel to shrink and move smoothly.

A hole ■ is opened in the open container ■, and when it is tilted as shown in Fig. I did it like that.

The drying container (■) containing the gel body (D) was covered with a lid (■) with a porosity of 12% and dried in a drying room at 55°C.The yield of the dry gel was very good, with 9 pieces out of 1011 cracked. It's perfectly done.

[Comparative Example 1] Cut 10 pieces of the same gel as μ ellipse 1, and fill it with 225
As shown in No. 15, the gel was placed in a horizontal state and placed in a drying container so that the direction of gel contraction and the direction of its own weight were perpendicular to each other. It was covered with a lid having a porosity of 0.2 inches and dried in a drying room at 55°C. The number of dry gels completed without cracking was 2- out of 10, and the other 8 were cracked.

[Example 5] #I commercially available ethyl silica) 4.51 and 11t
A solution of 11-hydrochloric acid added to pure water was vigorously stirred to obtain a colorless and transparent homogeneous solution. Thereto, 4 m/11 l of ultrafine powdered silica (trade name Aerosil Ox 50, Degussa Corporation) i75 was gradually added and stirred thoroughly. Further, this sol solution was irradiated with ultra-shuttle waves for 5 hours to ensure the dispersion of the ultrafine powdered silica. A centrifugal force of 1500G was applied to the sol solution.
The clumps in the sol bath were removed for 5 minutes to obtain a highly homogeneous sol solution.

The sol solution was diluted with Pl (5,0
Made of polypropylene with a very smooth surface (width 42 (?I x 52 x, width 81)
Pour an amount to a depth of approximately 1 clIH into a container, cover with a lid, and allow gelation to occur.

The gel was stored in a dry container in the same way as in Example 1 in a trap state. In addition, the separation water leached from the gel was allowed to flow out onto the bottom of the drying container to prevent the gel from soaking in the separation water.

The drying container was covered with a lid having a pore size of α3, and was dried in a drying room at 55°C. It took about 34 hours to complete the drying. The obtained dreigle is 513 x 24 tyx
It was X J*sa71.

The dry gel was placed in a gas Ilt exchange furnace (c) and heated at 30/min.
The temperature was raised to 900°C in 4 hours. Pure helium gas started flowing into the furnace at a flow rate of It/min from 900°C, and was heated to 1400°C at a rate of 30 C/11 r.
Hold at 1400℃ for 2 hours9.

The obtained quartz glass has a width of 25 cm x 17 cm x thickness of 5
．． It had a size of 51.

[Comparative Example 2] Ten sheets of the same gel as in Example 3 were placed in A'll, covered with a lid having a porosity of 13%, and dried in a drying room at 55° C. with the gel facing horizontally. I was able to dry 10 Chunichi sheets without printing, but 6 sheets were cracked.

[Run 4] Same gel as Example 3? Ten sheets were prepared and dried in an inclined state in the same manner as in Example 3. Ten Chunichi sheets were able to dry without cracking, but two did.

Compared to the method in comparison column 2, I! ] It was found that drying in the west was less likely to print and had a better yield.

[Example 5] The sol solution shown in Example 1 was adjusted to pH 5.0 and then placed in a polypropylene container (width 52 cns x 26
A bottle with a depth of 91cm (cm x height 10cm) was placed, the lid was closed, and the mixture was left to gel. It was electrostatically aged in a thermostatic chamber at 30° C. for 5 days. The thick gel? : It was dried in a drying room at 55°C in the same condition as in Example 1.

The obtained dry gel has a width of 218 tx x 19.5 cm x
It had a height of 651 cm.

〔Effect of the invention〕

As described above, according to the present invention, by tilting the gel in the drying container from the horizontal opening ρ1 during the gel drying process, the gel yield in the conventional drying process is greatly improved. This has the great effect of making it difficult for cracks to occur, and also making it easier to produce large thin sheets of glass and thick glass. Therefore, the present invention can overcome the general drawback of not being able to produce large bulk glasses using the sol-gel method, and will bring great benefits to the practical application of glass synthesis using the sol-gel method. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing a polypropylene container with afl& holes in the edges and sides. Figure 2 is a diagram showing how the gel is transferred to the container shown in Figure 1. Figure 3 is a diagram showing the gel and container shown in Figure 2 placed tilted inside the drying container. Container, ■... A hole provided to let the water flow out, ■... Drying container, ■... A lid with an opening. that's all

Claims (1)

[Claims] In the gel drying step of the quartz glass manufacturing method, which includes a sol solution preparation step, a gelling step, a gel drying step, and a gel sintering step, the gel in the drying container is tilted from the horizontal plane to shrink the gel. 1. A method for producing quartz glass, which comprises drying the quartz glass by arranging it so that the moving direction of the gel and the component force of the gel's own weight in the direction of the shrinking moving surface are in the same direction.