JP3668374B2 - Method for cleaning instruments in the production of multi-component gels - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing glass or ceramics by a sol-gel method.
[0002]
[Prior art]
Conventionally, as a method for producing glass and ceramics, for example, a sol-gel method using metal oxides such as metal alkoxide, water glass, and SiO ₂ as raw materials is known. This is the reaction of the above raw materials to produce an intermediate product sol, which is poured into a desired mold, etc. to produce a wet gel porous body, and then dried and fired to produce porous and dense glass or ceramics. It is a method to do.
[0003]
When producing multi-component glass or ceramics by a sol-gel method using a metal alkoxide and a metal salt, a metal alkoxide, a metal salt, an organic solvent such as alcohol, water is mixed to produce a sol solution, After pouring this into a desired container, drying and baking are performed to obtain a final product. During this process, metal alkoxides, metal salts, and sols reacted with these adhere to not only the reaction vessel but also various devices such as a filtration device and an injection device. At this time, if left untreated or improperly cleaned, metal alkoxides, metal salts, and sols that react with these will volatilize or react with moisture and cleaning fluid in the air to form particles on the surface of the instrument. However, when these are gelled and fired, there are problems such as generation of crystal defects and generation of foreign matters.
[0004]
Therefore, JP-A-9-100114 discloses a method for producing a synthetic quartz glass powder by baking a gel obtained by hydrolysis of alkoxysilane, after discharging the wet gel from the reaction vessel used for hydrolysis. It describes that the raw material is charged again after washing and discharging the washing liquid, and describes a method of washing with water or alcohol.
In the case of producing a wet gel by hydrolysis of alkoxysilane, there was a sufficient washing effect even by washing the reaction vessel with water or alcohol.
[0005]
[Problems to be solved by the invention]
When producing multicomponent glass or ceramics using metal alkoxide and metal salt as raw materials, various components are contained in the sol. For example, raw materials with different reaction rates and raw materials with different solubilities are contained in the sol, and if the cleaning method of the equipment is inappropriate, reaction products and precipitates will stick and become impossible to reuse, Caused contamination. For example, when an instrument is washed directly with water, the metal salt has a relatively high solubility in water, so the metal salt has a high cleaning effect, but an alkoxide having high reactivity with water, such as Ti, Nb, Ta, Zr, Al An alkoxide such as alkoxide or a derivative thereof reacts with water to form a precipitate and adheres to the instrument, making it impossible to reuse or causing contamination.
[0006]
Also, when washed with alcohol, it does not react with the alkoxide, so no precipitation occurs. For example, when ethanol is used, the solubility in the metal salt is relatively low, so the precipitation of the metal salt is sufficiently generated. Cleaning is not possible. In addition, when methanol is used, it does not react with the alkoxide and the solubility in the metal salt is relatively high, so precipitation is difficult to form, but both the metal alkoxide and the metal salt are sufficiently washed until contamination can be completely prevented. I couldn't. Moreover, even if it is washed with an alkoxysilane which is a silicon alkoxide, a metal salt precipitate is easily generated, and the alkoxysilane itself becomes an impurity, which is not preferable.
[0007]
In particular, when manufacturing optical glass, especially glass bodies with a refractive index profile, even slight contamination can cause striae and scattering, greatly affecting optical performance. There was a need to do.
[0008]
Even when various components are contained in the sol as in the case of producing multi-component glass or ceramics using metal alkoxide and metal salt as raw materials, the present invention includes a wet gel production process, etc. It is an object of the present invention to provide a method for producing glass or ceramics, which can prevent adverse effects due to reaction products caused by substances adhering to a tool and can reuse the used tool and the like.
[0009]
[Means for Solving the Problems]
The present invention relates to a method for cleaning a device in the production of a multi-component gel by a sol-gel method using a metal alkoxide and a metal salt as raw materials, and in the step of cleaning a device in contact with at least one of the metal alkoxide and the metal salt or the sol. And a cleaning method for an instrument that is cleaned with a second cleaning organic solvent miscible with water after being cleaned with a first cleaning organic solvent having a solubility in the metal salt of 0.001 mol / l or more.
[0010]
In this method, the first cleaning organic solvent having a solubility in a metal salt of a raw material of 0.001 mol / l or more is methanol, and the second cleaning organic solvent miscible with water is ethanol.
In a method for cleaning an instrument in the production of a multi-component gel by a sol-gel method using a metal alkoxide and a metal salt as a raw material, the metal alkoxide and the metal salt, or the instrument in contact with the sol, is at least one organic solvent miscible with water. It is the washing | cleaning method of the said instrument wash | cleaned using an acid after wash | cleaning using.
[0011]
In a method for cleaning an instrument in the production of a multi-component gel by a sol-gel method using a metal alkoxide and a metal salt as raw materials, the metal alkoxide and the metal salt, or the instrument in contact with the sol, has a solubility in the metal salt of 0.001 mol / l. This is a cleaning method for an instrument in which cleaning is performed using water after cleaning using at least one organic solvent.
This is a method for cleaning the above-described device, in which the device is cleaned with water after being washed with a solution containing methanol.
This is a method for cleaning the above-described device, in which the device is cleaned with a solution containing ethanol and then washed with a solution containing acetic acid, hydrochloric acid or nitric acid.
This is a method for cleaning an appliance as described above, wherein the metal alkoxide used as a raw material is an alkoxide of silicon and at least titanium or niobium, and the metal salt used as a raw material is a salt of an alkaline earth element or a rare earth element.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a method for producing a multi-component glass using a metal alkoxide and a metal salt, and the problems caused by the metal salt or metal alkoxide adhering to the container used for gelation of the sol are The problem is solved by using a specific liquid as the liquid.
[0013]
That is, when a multi-component glass is produced using a metal salt and a metal alkoxide as raw materials, the sol contains a metal alkoxide and a metal salt that are highly reactive with water. At this time, the instrument to which the sol is attached is first washed with an organic solvent. This organic solvent desirably has a certain degree of solubility in the metal alkoxide or metal salt used as a raw material. If the solubility is 0.001 mol / l or more, precipitation of the metal salt is unlikely to occur, and it is suitable for washing. / L or more is more desirable. Then, another metal solvent is used to wash away the metal alkoxide sufficiently. Since the first cleaning is performed, the metal salt is considerably cleaned. Therefore, even if the organic solvent for the second washing has a lower solubility in the metal salt than the organic solvent used for the first washing, precipitation does not occur.
[0014]
After this, it is more preferable that the instrument is thoroughly washed with a detergent or the like, and then washed with pure water. For example, when manufacturing optical glass or the like, not only impurities of metal but also any impurities must be avoided as much as possible. Therefore, it is necessary to finally clean the instrument used for the production of the sol with ion exchange water, pure water, ultrapure water, or the like. Therefore, the organic solvent used for washing in the present invention must be miscible with water.
[0015]
For example, when a sol is prepared by using an alkaline earth element acetate such as Ba as the metal salt and Si (OR) ₄ and Ti (OR) ₄ as the metal alkoxide, the sol attached to various instruments is as follows: Can be washed.
First, it is washed with an organic solvent, such as methanol, which does not precipitate Si and Ti alkoxides and dissolves alkaline earth element acetates such as Ba well. Next, when washing is performed with a solvent that dissolves Si and Ti alkoxides well, for example, ethanol, a large amount of precipitate is not generated, and it can be completely washed by subsequent washing with a detergent or the like.
[0016]
Also, in the method using water and acid, the metal alkoxide and the metal salt, or the device on which the sol reacted with these is first washed first with an organic solvent miscible with water, and then the residue is further removed by the first washing. Wash the material with water or acid solution. In particular, when the solubility of the organic solvent in the first washing with respect to the metal salt is 0.01 mol / l or more, the metal salt and the metal alkoxide are sufficiently removed, so that it is necessary to use an acid solution particularly in the second washing. However, even if washing is performed with water, washing can be carried out without producing a precipitate. Thereafter, it is more preferable that the instrument is sufficiently washed with a detergent or the like and further washed with pure water.
[0017]
Moreover, when the solubility with respect to the metal salt of the organic solvent mixed with the water used for 1st washing | cleaning is low, precipitation of metal salt generate | occur | produces by 1st washing | cleaning. However, in the subsequent second washing with the acid solution, the metal alkoxide remaining in the first washing reacts with the water in the acid solution to form a precipitate, but peptization occurs due to the acid and the precipitate dissolves. Has a high solubility in an acid solution, so that it can be sufficiently washed. In particular, when acetic acid, hydrochloric acid or nitric acid is used as the acid, it is preferable that peptization easily occurs. Thereafter, it is more preferable that the instrument is sufficiently washed with a detergent or the like and further washed with pure water.
[0018]
In addition, when a sol is prepared using an alkaline earth element acetate such as Ba as the metal salt and Si (OR) ₄ and Ti (OR) ₄ as the metal alkoxide, the sol attached to various instruments is as follows: Can be washed.
First, it is washed with an organic solvent, such as methanol, that does not precipitate Si and Ti alkoxides and that well dissolves alkaline earth element acetates such as Ba. Next, when it is washed with a large amount of water, no precipitate is formed, and it can be completely washed by subsequent washing with a detergent or the like.
Further, it is washed with an organic solvent that dissolves Si and Ti alkoxide well, for example, ethanol. At this time, Ba acetate precipitates, but the precipitate of Ba acetate dissolves when washed with an acid, for example, diluted acetic acid, and can be completely washed by subsequent washing with a detergent or the like.
[0019]
In the present invention, when the metal alkoxide cannot be sufficiently removed by the first cleaning, the cleaning can be effectively performed by performing the cleaning after the second cleaning with the acid solution. The metal alkoxide remaining in the first washing reacts with water in the acid solution to form a precipitate, but peptization is caused by the acid and the precipitate is dissolved to enable sufficient washing. As the acid, when acetic acid, hydrochloric acid or nitric acid is used, it is preferable that peptization easily occurs. For example, when manufacturing optical glass or the like, it is necessary to avoid contamination of any impurities as much as possible, not limited to metal impurities. Therefore, it is necessary to finally clean the instrument used for the production of the sol with ion-exchanged water, pure water, ultrapure water, or the like. Therefore, it is necessary to mix the organic solvent used for washing in the present invention with water.
[0020]
The present invention described above is particularly effective when the following raw materials are combined. Titanium or niobium alkoxide, which is a metal alkoxide that reacts relatively slowly with water, and a reaction between water and titanium alkoxide, and a salt of an alkaline earth element or rare earth element that has a relatively low solubility in an organic solvent as a raw material for the metal salt, Of these, organic salts, particularly acetates, are effective.
[0021]
As described above, in the cleaning method using both the metal alkoxide and the metal salt as raw materials, the nature of the cleaning liquid and the order in which it is used for cleaning are very important. Even if the same cleaning solution is used, care should be taken because a precipitate will be generated if the order is incorrect.
[0022]
【Example】
The following examples illustrate the invention.
Example 1
125 ml of 0.01 N hydrochloric acid was added to 250 ml of tetramethyl silicate and stirred for 1 hour to carry out a partial hydrolysis reaction. A mixture of 498 ml of a 1.5 mol / l aqueous solution of barium acetate and 200 ml of acetic acid was added thereto. This was further stirred for 30 minutes, then filtered, poured into 200 fluororesin containers having an inner diameter of 10 mm and having high roundness, and the container was covered and sealed to be gelled at room temperature. .
After use, the reaction vessel and the filtration device were immediately washed with methanol, followed by a second wash with ethanol, further washed with a detergent, and then sufficiently rinsed with ultrapure water and dried.
[0023]
The obtained gel was aged for 5 days, and further immersed in a 0.45 mol / l solution of barium acetate using a mixed solvent of isopropanol: water = 6: 4 at 60 ° C. to remove acetic acid. By immersing the gel in a mixed solvent of methanol and ethanol and ethanol, barium acetate microcrystals were precipitated and fixed in the pores of the gel.
[0024]
The obtained homogeneous gel was immersed in a methanol solution of 0.3 mol / l potassium acetate in methanol for 8.5 hours to give a concentration distribution, and then immersed in the order of ethanol: acetone = 5: 5, acetone and acetone. , Fine crystals of barium acetate and potassium acetate were precipitated and fixed in the gel pores. It was dried from 30 ° C to 100 ° C gradually. Thereafter, the glass body was put into an electric furnace and oxygen was passed through to 450 ° C., and helium was passed from 450 ° C. to 700 ° C. to obtain a dense glass body. It was possible to obtain a glass body having no cracks, colorless and transparent, and having no striatal defects. When the refractive index distribution in the radial direction of the glass body was measured, a glass body having a substantially parabolic distribution could be obtained.
The above steps were repeated using a washed reaction vessel and filtration apparatus, but no impurities were observed in the final glass, and the glass was a high-quality glass body.
[0025]
Example 2
The sol was prepared in the same manner as in Example 1, and the reaction vessel and the filtration device were washed with ethanol and then diluted with acetic acid, then washed with a detergent, and then sufficiently rinsed with ultrapure water and dried.
The obtained gel was processed in the same manner as in Example 1. The above steps were repeated using a cleaned reaction vessel and filtration device, but no impurities were found in the final glass, and the glass was a high-quality glass body.
[0026]
Comparative Example 1
A sol was prepared in the same manner as in Example 1. The reaction vessel and the filtration device were washed with ethanol and then with methanol, but the produced precipitate was not dissolved, and the device became unusable.
[0027]
【The invention's effect】
Since the tools in contact with the sol such as the metal alkoxide and the metal salt or the sol production container are washed with an appropriate solvent, a high-quality glass body can be produced with a high yield.

Claims (2)

  In the method for cleaning an instrument in the production of a multi-component gel by a sol-gel method using a metal alkoxide and a metal salt as raw materials, the instrument in contact with at least one of the metal alkoxide and the metal salt or the sol has a solubility in the metal salt of 0. A cleaning method for an instrument, comprising: cleaning with a second cleaning organic solvent miscible with water after cleaning with a first cleaning organic solvent of 001 mol / l or more.  The first cleaning organic solvent having a solubility in a metal salt of a raw material of 0.001 mol / l or more is methanol, and the second cleaning organic solvent miscible with water is ethanol. Cleaning method.