JPH0345519A - Production of glass from liquid phase - Google Patents

Abstract

PURPOSE:To prevent cracking or crushing from occurring in converting a metal alkoxide into a dry gel and obtain large-sized glass by hydrolyzing and gelatinizing the metal alkoxide in the coexistence of a specific amount of a specified nitrogen-containing organic compound in a sol-gel method. CONSTITUTION:A metal alkoxide, an alcohol, water and further, as necessary, a catalyst are used to produce glass. In the method, the metal alkoxide is hydrolyzed and gelatinized in the coexistence of one or more N-containing organic compounds, such as acetamide, pyrrolidone and polyacrylamide, in an amount of 10-300wt.% based on the metal alkoxide. The resultant gel is then passed through steps for forming a dry gel and burning the dry gel to produce the objective glass. N- and N,N-substituted acetamides, N-substituted purrolidones, polyamic acids, caprolactam, polyamide resins, nitrile group-containing compounds and oxazoline are cited as the specific N-containing organic compound in addition to the aforementioned compounds.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for producing glass from a liquid phase by a sol-gel method, and particularly to a method for producing glass using a metal alkoxide as a raw material.

(Description of Prior Art) Melting methods, chemical vapor phase reaction methods, sol-gel methods, etc. are known as methods for producing high-performance or high-quality glass, but the melting method requires high temperatures of 2200 to 2300°C. In addition, the chemical vapor phase reaction method has the disadvantage that a considerable portion of the raw material for glass flows out of the reaction system, resulting in a low conversion efficiency of the raw material to glass.

In contrast, the sol-gel method involves gelation of a solution or sol,
Glass is produced by heating gel, and this method was devised to overcome the drawbacks of the melting method or chemical vapor phase method. Generally, glass can be produced by heating at a relatively low temperature, and the raw material glass However, cracks occur during the conversion of the starting solution or starting gel into a dry gel body, or when the dry gel body is converted into a glass body by heating.

Another drawback was that it was difficult to obtain large glass bodies due to deformation due to crushing and abnormal expansion.

Therefore, as a method of obtaining a large glass body while compensating for these drawbacks, a method using a sol of metal oxide fine particles as a starting material and a method of adding metal oxide fine particles to a metal alkoxide solution in advance have been proposed. However, these methods require 1200 ml to convert a dry gel body into a transparent glass body.
This method requires a heating temperature of .degree. C. or higher, which has the disadvantage that the advantages of the sol-gel method described above are lost.

On the other hand, a method for producing glass using a starting solution containing only metal alkoxides as the glass source has also been proposed, in which the sintering temperature when converting the dry gel body into glass is low, but in particular the solution Cracks and fractures are likely to occur when the initially gelled soft gel turns into a dry gel body by drying.

The cause of cracks and fractures caused by this manufacturing method is that the pores are so small that the skeleton of the gel cannot withstand the compression caused by the large surface tension that is applied when the gel contracts due to evaporation of water in the solution. This is thought to occur because the difference in drying shrinkage becomes large between parts of the body close to the free surface and parts far from the free surface, creating a large stress between the image parts.

Therefore, as a method to prevent cracking and crushing,9 for example, a method of drying in an autoclave under supercritical conditions.

Measures such as slow heating drying, adding a large amount of hydrochloric acid, and using formamide or N,N-dimethylformamide as a drying control agent have been taken. With the method using hydrochloric acid, it is difficult to obtain a sufficiently large dried gel body, and with the method of slow drying, glass production takes a long time and is not practical. Also, formamide and N are used as drying control agents.

When N-dimethylformamide is used, there is a drawback that it is difficult to set two conditions because the influence of the base or acid as a catalyst is large.

The present invention has been made in view of the above background.
The purpose is to prevent the occurrence of cracks or fractures during conversion into a dry gel.

It is an object of the present invention to provide a method for manufacturing glass by a sol-gel method, which allows transparent, large-sized glass to be obtained while avoiding high temperatures during sintering.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a method for producing glass using a metal alkoxide, alcohol, water, and, if necessary, a catalyst as starting materials.
0% by weight of acetamide, N-substituted acetoamide, N
, N-substituted acetamine, pyrrolidone, N-7-substituted pyrrolidone, polyacrylamide.

Boria also contains citric acid, caprolactam, and boria resin.

The metal alkoxide is hydrolyzed and gelated in the coexistence of one or more nitrogen-containing organic compounds selected from nitrile group-containing compounds and oxaprines.

This is a glass manufacturing method using a sol-gel method in which glass is then produced through a dry gel production process and a dry gel sintering process.

The nitrogen-containing organic compound used in the above production method is one that is well mixed with a mixed solution of metal alkoxide, water, and alcohol. Moreover, in order to increase the solubility in water, it may be neutralized with an acid or a base.

The above acetamide, Ni-substituted acetoamide, N.

Examples of the N-substituted acetamide include acedoacetamide, N-methylacetamide, N,N-dimethylacetamide, N-vinylacetamide, and the like.

The above pyrrolidone and N-substituted pyrrolidone include:

Examples include 2-pyrrolidone, N-methylpyrrolidone, N-vinylpyrrolidone, polyN-vinylpyrrolidone, and the like.

Examples of the caprolactam include ε-caprolactam.

Examples of the above polyamide resins include 9, polyamide 4,
6 resin, polyamide 6.6 resin, boria 6.6 resin, boria godo II resin, condensate of dimer acid and polyamine, and the like.

The nitrile-containing compound is acetonitrile.

Examples include propionitrile, butyronitrile, acrylonitrile, polyacrylonitrile, and the like.

Other nitrogen-containing organic compounds that can be used in this method include N-methylformamide, N,N-diethylformamide, polyacrylamide, and polyamic acid 1.

Examples of the alcohol include methyl alcohol, ethyl alcohol, n-propanol, isopropanol, glycerin, and the like.

Examples of the metal alkoxide include silicon alkoxide such as tetraethyl silicate and tetramethyl silicate, germanium alkoxide, titanium alkoxide,
Examples include zirconium alkoxide. Moreover, a mixture of two or more types of these metal alkoxides may be used.

In the dry gel production process, for example, if this is carried out in a glass container, the gel body will adhere to the glass wall.

Since cracks occur in the dried gel when it shrinks, use a container made of fluorine thread resin that is heat resistant to the temperature of about 150°C, which is the temperature for producing a dry gel body, or a container coated with fluororesin, or a container coated with polymethylpentene resin, etc. It is recommended to use a container of

The gel is dried in the above container, and the drying temperature is 120℃.
It is desirable to carry out at -150 degreeC. If the drying temperature is lower than 120° C.9 For example, if drying is carried out at a constant temperature of 100° C., cracks are likely to occur just before the drying of the gel is completed, and drying takes a long time.

The dried gel obtained in this way is porous with human-sized pores, which are sintered at a predetermined temperature to make them finer.

Glass is obtained by making it non-porous.

Note that if the amount of the nitrogen-containing organic compound added to the metal alkoxide is less than 10% by weight, it is not effective in preventing the occurrence of cracks during gel drying, and if it is more than 300% by weight, only a gel with low strength is obtained, and the metal alkoxide The molar ratio of water to water can be added arbitrarily depending on the purpose.

(Example) The details of the present invention will be explained below using Examples.

Example 1 10 g of tetramethoxysilane was added to a mixed solution of 10 g of water, 5.5 g of methanol, and 3 g of N,N-dimethylacetamide.
After stirring at room temperature for 10 minutes, the mixture was placed in a polymethylpentene resin cylinder, covered with aluminum foil, sealed, and kept at 40°C. After gelling in this way, 8
The temperature was raised to 0°C in 48 hours, and 10 pinholes (about 1 mm in diameter) were opened at 80°C to start drying. After that, 15
By raising the temperature to 0℃ over 96 hours, the diameter of
The result was a brownish, almost transparent dry gel rod with mn+ and a length of about 401 cm. The dried gel was sintered by increasing the temperature to 1050° C. at a rate of 15° C./hour in an atmosphere of air in an electric furnace.

As a result, a transparent silica glass rod with an iW diameter of about 12 mm and a length of 28 mm was obtained. The density of this glass is 2.
The density was 2 g/c1, the same as commercially available quartz glass.

Example 2 Water Log, methanol s, sg + propionitrile 5g
To the mixed solution was added 10 g of tetramethoxysilane at once, and after stirring at room temperature for 10 minutes, the mixture was placed in a polymethylpentene resin cylinder, covered with Al' and foil, hermetically sealed, and kept at 40°C. After gelatinizing in this way, the temperature was raised to 80°C in 48 hours, and at 80°C, a pinhole (about 1 mm in diameter) was cut into 1 pinhole.
When 0 pieces were opened, drying started. Thereafter, the temperature was raised to 150° C. over 96 hours, resulting in a brownish, almost transparent dried gel rod with a diameter of about 17 nun and a length of about 40 mm. The dried gel was sintered in an electric furnace by increasing the temperature to 1050° C. at a rate of 15° C./hour in an atmosphere of air composition. Due to this.

A transparent silica glass rod with a diameter of about 12 nus and a length of 28+1101 was obtained. The density of this glass is 2.2g
/cm3, which was the same density as commercially available quartz glass.

Examples 3 to 7 In place of N and N-dimethyl acedodando in Example 1, acetamide, polyacrylamide (molecular weight approximately 10,000), ε-caprolactam, and Tomide 2500 were used, respectively.
When glass was produced in the same manner as in the Examples using Boria ξ resin (manufactured by Fuji Kasei ■) or oxazoline, almost the same results were obtained.

Example 8 10 g of water, 9.5 g of isodiisotool, 4. 4'
10 g of tetramethoxysilane was added to a mixture consisting of 3 g of a 20% solution of N,N-dimethylacetic acid 551, which was prepared from cyanodiphenyl ether pyromellitic dianhydride, and 0.1 g of 28% aqueous ammonia, and the mixture was heated to 10 g at room temperature. After stirring for several minutes, the mixture was placed in a trimethylpentene cylinder covered with aluminum foil, and gelatinized at 40°C. Thereafter, the temperature was raised to 80°C over 48 hours, ten holes (about 1 mm in diameter) were made in the aluminum foil, and the temperature was raised to 150°C over 96 hours to obtain a brown, opaque dry gel.

The dried gel is heated in an electric furnace in an atmosphere of air and air.
The temperature was raised to 1 oso° C. at a rate of 5° C./hour for sintering.

Due to this.

A transparent silica glass rod with a diameter of approximately 12 mm and a length of 28+++ m was obtained. The density of this glass is 2.2g/c
m3, and had the same density as commercially available quartz glass.

Example 9 LOg of water, 9g of isopropanol, vinylpyrrolidone
10 g of tetraethoxysilane was added to a mixed solution of 3 g of acetic acid and 0.1 g of acetic acid, stirred at room temperature for 10 minutes, and then left to gel. Thereafter, the temperature was raised to 80°C over 48 hours to mature the gel, and the temperature was further raised to 150°C over 96 hours to obtain a white dry gel body without cracks.

Example 1O 6 g of tetramethoxysilane was added to a mixed solution of 10 g of water, 5.5 g of metadimeth, and 3 g of N,N-dimethylacetamide.
Add 4g of tetramethoxyzirconium at once.

After stirring at room temperature for 10 minutes, the mixture was placed in a polymethylpentene resin cylinder, covered with aluminum foil, sealed, and kept at 40°C. After gelatinization in this manner, the temperature was raised to 80° C. over 48 hours, and at 80° C., 10 pinholes (about 1 mm in diameter) were opened and drying was started. After that, by raising the temperature to 150℃ over 96 hours, it becomes approximately 17mm in diameter and approximately 40m in length.
The result was a brownish, almost transparent dry gelrond.

The dried gel was heated to 15°C in an atmosphere of air composition in an electric furnace.
The temperature was raised to 1050° C./hour to sinter. As a result, a transparent silica zirconia glass iron having a diameter of about 12 am and a length of 28 mm was obtained.

Comparative Example 1 A log of tetramethoxysilane was added at once to a mixed solution of 10 g of water and 5.5 g of methadimeta, and after stirring at room temperature for 10 minutes, the mixture was poured into a polymethylpentene resin cylinder and sealed with an aluminum foil lid. The temperature was kept at 40°C.

After gelatinization in this manner, the temperature was raised to 80° C. over 48 hours, and at 80° C., 10 pinholes (about 1 mm in diameter) were opened and drying was started. Thereafter, the temperature was raised to 150° C. over 96 hours to obtain a dry gel body, which was crushed into numerous small pieces.

Comparative Example 2 10 g of tetramethoxysilane was added to a mixed solution of 10 g of water, 5.5 g of metadimeth, and 3 g of N,N-dimethylformamide.
was added at once, and after stirring at room temperature for 10 minutes, the mixture was placed in a polymethylpentene resin cylinder, covered with aluminum foil, hermetically sealed, and kept at 40°C. After gelling in this way, 80℃
The temperature was raised to 80'C over 48 hours, and drying was started by opening a pinhole (about 1 mm in diameter) in 1O. After that, 150
Although the temperature was raised to ℃ over 96 hours, the dried gel body was crushed into countless small pieces.

Comparative Example 3 10 g of aqueous ammonia of 4×10-”mol/I, 5.5 g of methanol, 3 g of N,N-dimethylformamide
10 g of tetramethoxysilane was added to the mixed solution at once, and after stirring at room temperature for 10 minutes, the mixture was placed in a polymethylpentene resin cylinder, covered with an Al main seedling, hermetically sealed, and kept at 40°C. After gelatinizing in this way, the temperature was raised to 80°C in 48 hours, and at 80°C, 10 pinholes (about 1 mm in diameter) were cut.
Individual openings have started drying. Thereafter, the temperature was raised to 150° C. over 96 hours, and a milky white dry gel was obtained.

〔Effect of the invention〕

As explained above, in the method of the present invention, a crack-free dry gel body can be created by adding a nitrogen-containing organic compound to a raw material alkoxide solution.

The cause of this is not necessarily clear, but it is the low polarity 1 surface tension of nitrogen atoms.

Many things seem to be involved, including vapor pressure. Also,
The pore distribution of these dry gel bodies produced by the method of the present invention can be controlled, and when silica glass is doped with compounds such as metals and halogens.

Controlling the pore distribution is also considered effective in suppressing the diffusion rate when the dry gel is immersed in a solution containing a dopant and the dopant is diffused into the pores.

Furthermore, according to the present invention, a dry gel body without cracks can be obtained without using a catalyst such as a base or an acid, and the resulting dry gel body has high transparency and can be used at a lower temperature than that using a catalyst. It seems that transparent glass can be obtained.

Furthermore, according to the method of the present invention, it is possible to composite glass and a nitrogen atom-containing organic polymer, Neptumer, at the molecular level, making it possible to obtain novel structural materials and composite materials. .

Claims (1)

[Claims] 1. In a method for producing glass using metal alkoxide, alcohol and water, and optionally a catalyst, 10-300% by weight of acetamide, N-substituted acetamide, N,N-substituted acetamide based on the metal alkoxide. , pyrrolidone, N-substituted pyrrolidone, polyacrylamide, polyamic acid, caprolactam, polyamide resin, nitrile group-containing compound, and oxazoline in the coexistence of one or more nitrogen-containing organic compounds, and the metal alkoxide is hydrolyzed into a gel. to become
A method for producing glass from a liquid phase by a sol-gel method, characterized in that glass is produced through a dry gel production step and a dry gel sintering step.