JPS62100426A - Production of glass - Google Patents

Abstract

PURPOSE:To reduce the drying stage and to produce glass at a low cost by carrying out aging when glass is produced by a sol-gel method at a specified temp. CONSTITUTION:In the production of glass by a sol-gel method, ageing is carried out at >=40 deg.C. The ageing stage and the drying stage can be reduced by the above-mentioned method without decreasing the yield when a dry gel is prepared from a wet sol. Namely, the wet gel is contracted to a smaller volume than before in the ageing stage not significantly affecting the yield, and is not significantly contracted in the drying stage affecting the yield greatly to prepare the dry gel. The ageing in this case means that the wet gel is allowed to stand at a certain temp. in a closed state. The wet gel during ageing is contracted as the dehydration and condensation reactions proceed, and a solvent such as water is removed from the gel.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for producing glass by a sol-gel method,
By performing the aging at a temperature of 40° C. or higher, the drying process can be shortened and glass can be produced at low cost.

[Conventional technology]

Regarding the method of manufacturing glass using the conventional sol-gel method,
Although there are various reports, there is a major barrier that can be used industrially.
・The method for producing Kugarasu is described in detail in the patent. (Patent Application No. 58-237577, ■Patent 1 U85 Glass Manufacturing Method Part) [Problems and Objectives to be Solved by the Invention] However, in the above-mentioned conventional technology, when drying the wet gel, the drying speed is slow. If dried too quickly, it would easily break, so it took about two weeks to dry slowly and carefully. As a result, a large number of large dryers were required during mass production, which ultimately became an obstacle to significantly reducing costs.

□Means for Solving the Problems] The method for producing glass of the present invention is characterized by aging at a temperature of 40° C. or higher in the method for producing glass by a sol-gel method.

[Effect]

According to the above configuration of the present invention, the aging and drying steps can be shortened without lowering the yield when producing a dry gel from a wet gel.

In other words, wet gel is shrunk to a smaller volume than before in the aging process, which has little effect on yield, and dry gel can be produced without much shrinkage during drying, which has a large impact on yield.

Here, aging refers to leaving the wet gel in a sealed state at a certain temperature. During aging, the wet gel shrinks as the dehydration condensation reaction progresses, and solvents such as water are removed from the gel. released. Drying, on the other hand, involves leaving a wet gel at a certain temperature in a container with a certain opening, and during drying, solvents such as water are released from the surface of the gel. As the dehydration condensation reaction progresses, the gel shrinks. For this reason, it is thought that the balance between the dehydration condensation reaction and the release of solvents such as water is more likely to be lost in the drying step than in the ripening step, and this is probably why the yield is poor.

This will be explained in detail below using examples.

[Example 1] Ethyl silicate 1830.6 t, absolute ethanol 23169.29% ammonia water 70.5 f, water 633
After stirring vigorously for 2 hours, the mixture was aged in a cool dark place to grow fine silica particles. After concentrating this solution under reduced pressure, the alcohol content of the concentrated solution was partially replaced with water in order to increase the yield of the drying process. After that, the pH value was adjusted to 4.0 using 2N hydrochloric acid to prevent rapid gelation when mixed with the hydrolysis solution, and further
The mixture was filtered using a 0 μm membrane filter to prepare a dispersion solution of silica fine particles having an average particle size of 0.28 μm, which was used as a first solution.

844 t of 002N hydrochloric acid was added to 1220.3 t of ethyl silicate, and the mixture was hydrolyzed with vigorous stirring to obtain a second solution.

Next, the first solution and the second solution were mixed, and then the pH value was adjusted to 485 using 02N ammonia water and water.
The volume was adjusted to 40001 nl to prepare a sol solution. The sol solution was poured into six cylindrical containers (inner diameter 401111
．． After transferring the container to a height of 550 m to a depth of 500 m, the container was air-conditioned for 2 minutes, and then sealed with a lid. Approximately 40 minutes after pH adjustment, gelation occurred and a wet gel was obtained.

270 wet gels prepared in a similar manner were aged in a sealed state under various conditions for 5 days, and then only the wet gels were transferred to dry containers with various opening ratios, i.e., the released solution was discarded. ), a dry gel was obtained when dried.

The yield is shown in Table 1.

Table 1) Cannot be measured due to loss of shape As shown in the first section, it can be seen that the higher the ripening temperature, the better the yield. However, if the ripening temperature is too high, the vapor pressure of the solvent will increase and the yield will decrease. Upon further investigation, it was found that the yield decreased when the temperature exceeded 70°C. This is presumed to be because at that temperature, the vapor pressure of ethanol and water contained in the sol increases, causing boiling.

To shorten the drying process (for example, within one day)
For example, by increasing the boiling point of the alcohol in the gel by using raw materials such as tetrabutoxygermanium, or by pressurizing the aging container to prevent it from boiling to a higher temperature, dehydration condensation reactions and solvents such as water can be achieved. This could be achieved by shrinking it to a smaller volume without disturbing the balance of its release.

The value −(%) obtained by dividing the size of the wet gel after ripening by the size of the wet gel before ripening is also shown in the table.
The gel aged at high temperature ζ, the amount of shrinkage of the wet gel after the first aging until it becomes a dry gel is small, and it is presumed that it will shrink easily even if the drying speed is increased in the drying process. A transparent pure quartz rod was obtained by sintering the dried gel under the following conditions (outer diameter: 23mm, length: 460mm). As a result, an optical fiber having a core diameter of 200 μm and a cladding diameter of 300 μm was obtained. The transmission loss of the obtained optical fiber was 0.25μ
It was confirmed that the optical fiber was less than 1 l in m and could be sufficiently used as an optical fiber for LAN.

(Sintering conditions) Dry gel was placed in a quartz tubular furnace and the temperature was increased at a rate of 30°C/hr.
The temperature was heated from 30°C to 200°C, held at this temperature for 5 hours, and then heated from 200°C to 300°C at a heating rate of 30'Q/hr, and held at this temperature for 5 hours to remove the desorbed water. I did it. Next, increase the temperature at a rate of 30℃/hr to 3.
It was heated from 00° C. to 920° C. and held at this temperature for 30 minutes to perform decarbonization, dechlorination ammonium treatment, and acceleration treatment of dehydration condensation reaction. Then He 2 l/m
The temperature was maintained for 1 hour while flowing a mixed gas of i n , O 102/m 1n, the temperature was raised from 920'C to 1000°C, and the temperature was maintained at 1000°C for 2 hours to perform OH group removal treatment. Followed by 0. 171/m
110 at a heating rate of 60°C/hr from flowing water
The temperature was raised to 0° C. and held at that temperature for 20 hours to perform dechlorination treatment. Subsequently, without flowing only H., it was heated to 1250° C. at a temperature increase rate of 30° C./hr, and held at this temperature for 1 hour to perform a pore-closing treatment. Subsequently, the sample was heated to 1400° C. at a heating rate of 60° C./hr and held at this temperature for 30 minutes, becoming non-porous and transparent glass.

In this example, an example of a pure quartz rod used as a core base material for an optical fiber for LAN is shown, but the present invention is not limited thereto, and can be applied to all types of glass manufactured using the sol-gel method. It is valid for For example, optical fiber base material 1 quartz tube.

It has a wide range of applications, including quartz photomask substrates, Tie, -8in, and low expansion glass.

〔Effect of the invention〕

As described above, according to the present invention, in the glass manufacturing method using the sol-gel method, by performing aging at a temperature of 40 tl or more, it is possible to shorten the drying process, so glass can be manufactured at a low cost. Now you can.

Therefore, the present invention is applicable to sols, which are currently expanding their scope of application.
This will become a major technology for glass manufacturing methods using the gel method.

that's all

Claims (1)

[Claims] A method for producing glass using a sol-gel method, characterized by aging at a temperature of 40°C or higher.