JPH0794326B2 - Method for producing SiO 2 lower porous glass - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a SiO ₂ -based porous glass, and in particular, has a large number of fine pores such as a separation membrane and an enzyme carrier and is excellent. The present invention relates to a method for producing a SiO ₂ -based porous glass used as a porous material which is required to have heat resistance and corrosion resistance.

(Prior art) A porous material such as a separation membrane or an enzyme carrier must have a large number of fine pores, for example, a pore radius of about 5 to 10Å and have excellent heat resistance and corrosion resistance. Is. On the other hand, SiO ₂ -based glass is excellent in heat resistance and acid resistance, SiO ₂ system glass containing ZrO ₂ among them (ZrO ₂ -SiO ₂ glass) is excellent in heat resistance, is excellent in alkali resistance. Therefore, SiO ₂ glass (ie,
If SiO ₂ -based porous glass) can be stably and practically produced, it can be suitably used as a porous material such as a separation membrane or an enzyme carrier.

Conventionally, as a method for manufacturing a SiO ₂ -based porous glass, a manufacturing method using a phase separation phenomenon of glass and a manufacturing method using a sol-gel method are known.

In the former manufacturing method, SiO ₂ glass containing various metal oxides is heat-treated at a temperature below the softening point for a long time to form a skeleton of Si.
An O ₂ phase and a soluble metal oxide phase are separated, and the soluble phase is eluted with an acid to produce a SiO ₂ -based porous glass.

The latter manufacturing method is a method in which a silicon alkoxide (or silicon alkoxide and an alkoxide of a metal other than silicon) is hydrolyzed to form a sol, which is then gelled and dried to form a porous dry gel. Is gradually heated to synthesize glass by evaporation of water in the gel and dehydration condensation reaction to produce a SiO ₂ -based porous glass.
If the heating temperature of the dry gel is further increased, the glass will be densified by the sintering reaction and the pores will disappear, so that porous glass cannot be obtained.

(Problems to be solved by the invention) However, among the conventional methods for producing a SiO ₂ -based porous glass, in the production method utilizing the phase separation phenomenon of glass, the pore radius is 20 Å or less You ca n’t manufacture things,
In addition, since the separated ZrO ₂ is eluted with acid, the content of ZrO ₂ is
Since it is limited to 5 mol% or less, there is a problem that the alkali resistance is not sufficient.

In the conventional porous glass manufacturing method using the sol-gel method, the content of ZrO ₂ can be increased, so there is no problem in terms of alkali resistance, but the pore radius is 10 Å In order to manufacture, it is necessary to take measures such as stopping the heating just before the glass produced by heating the dry gel becomes densified, but since the densification of glass occurs rapidly in a narrow temperature range, control is possible. Is difficult. For example, 300 dry gels
When heated at about 500 ° C, the strength and corrosion resistance of the produced glass are not sufficient, and when heated at 500 ° C or higher, it becomes difficult to control the pore size.

In addition, since the micropores change depending on the temperature of sol formation, gelation, and gel heating due to hydrolysis, the state of the micropores generated is naturally determined by the production conditions, but the production conditions are controlled to be constant and accurately. Since it is extremely difficult to control the state of the micropores, it is difficult to control the state of the micropores. The state of the fine pores is basically the size (radius) of the fine pores and the distribution and number of the fine pores, but practically, the radius of the fine pores and the size and number of the fine pores are practically used. It is the surface area of the micropores per unit weight of glass (hereinafter referred to as the specific surface area), etc. that is determined by the Further, it is an important factor for evaluation.Moreover, it takes time to heat the dry gel, so if you try to shorten the heating time by heating rapidly at high temperature, unreacted organic matter remains and the glass tends to blacken due to pyrolytic carbon. There is a drawback that In order to prevent this, it is advisable to perform steam treatment by gradually raising the temperature in steam before heating the dry gel, and then heat the dry gel. Requires.

The present invention has been made in view of such circumstances, and its purpose is to solve the above-mentioned problems of conventional ones, and to manufacture a SiO ₂ -based porous glass by a sol-gel method. In this case, the pore radius: 5 ~ 10 Å can be produced with those having fine pores, the glass strength and corrosion resistance can be improved as compared with the conventional method by the sol-gel method, and the fine pores of the glass It is easy to control the state (fine pore radius and specific surface area, etc.), has excellent reproducibility, and is a method for producing a SiO ₂ -based porous glass that can suppress blackening of glass without steam treatment for a long time. It is the one we are trying to provide.

(Means for Solving the Problems) In order to achieve the above object, the method for producing a SiO ₂ porous glass according to the present invention has the following constitution.

That, SiO ₂ based porous glass manufacturing method according to claim 1, upon producing a SiO ₂ based porous glass by the sol-gel method, polyethylene glycol is an organic polymer, polypropylene glycol, polyacrylic acid, For a solution in which one or more organic polymers selected from polyvinylpyrrolidone and polyvinyl alcohol are dispersed in a solution containing silicon alkoxide, the silicon alkoxide is hydrolyzed to form a sol, and then the sol containing other than silicon is added. A solution containing a metal alkoxide is added and mixed, and the metal alkoxide is hydrolyzed to form a sol and then gelled, which is dried to form a dry gel, which is dried at a temperature of 500 to 800 ° C. by removing the organic polymer in the dry gel with vitrified heated, SiO ₂ based porous glass having fine pores SiO _2, characterized in that to obtain
This is a method for producing a porous glass.

The method for producing a SiO ₂ -based porous glass according to claim 2, wherein the dry gel is subjected to a steam treatment in which the temperature is gradually raised and heated in steam before the dry gel is heated.
This is a method for producing O ₂ -based porous glass.

SiO ₂ based porous glass manufacturing method according to claim 3, alkoxide of a metal other than the silicon is SiO ₂ based method for producing a porous glass according to claim 1 zirconium alkoxide.

(Operation) As described above, the method for producing a SiO ₂ -based porous glass according to the present invention is one selected from organic polymers such as polyethylene glycol, polypropylene glycol, polyacrylic acid, polyvinylpyrrolidone, and polyvinyl alcohol, or Two or more types of organic polymers (hereinafter referred to as specific organic polymers)
In a solution containing silicon alkoxide is hydrolyzed to form a sol, and then a solution containing a metal alkoxide other than silicon (hereinafter referred to as other metal alkoxide) is added and mixed to the sol. Since the metal alkoxide is hydrolyzed to form a sol, which is further gelled and then dried to form a dry gel, a dry gel containing a specific organic polymer can be obtained.

Here, in the sol formation by hydrolysis, the order as described above is that silicon alkoxide has a lower reaction rate of hydrolysis than other metal alkoxides, and the composition is obtained by hydrolysis from a substance having a low speed. This is because a homogeneous sol can be obtained, and as a result, a dry gel having a uniform composition can be obtained, and the function of glass can be further improved. That is, if the other metal alkoxide is hydrolyzed first, its sol formation is fast, so that it is not uniformly mixed when the silicon alkoxide is added, and it becomes difficult to obtain a homogeneous sol. Even in the case of making it possible, it becomes difficult to obtain a uniform sol. As a result, the sol and the dried gel according to the present invention have a uniform composition.

On the other hand, the specific organic polymer is a long and thin substance having a length of about 5 to 20Å, which can be uniformly dispersed in a solution containing a silicon alkoxide, resulting in a homogeneous composition and a uniform specific organic polymer. A dispersed dry gel is obtained.

Next, since the dry gel is heated at a temperature of 500 to 800 ° C. to be vitrified by a dehydration condensation reaction and the organic polymer in the dry gel is removed, the removal of fine particles as described below is performed. Is formed.

That is, the dry gel is porous containing the specific organic polymer, and the specific organic polymer coexists with the pores of the gel itself. The substance is gasified and discharged in addition to the gel, and a gas passage is formed in the gel during the vitrification process, through which the specific organic polymer is sequentially discharged (removed) out of the glass.

By such heating and removal of the specific organic polymer, the removed portion itself remains as elongated micropores, and elongated fine pores are formed, and the fine pores of the dry gel itself are not made nonporous. Since it remains and more micropores are formed,
The pore radius can be about 5-10Å. Although the reason for the formation and retention of the fine pores is not well understood, the formation of fine pores in the dry gel itself is promoted and disappears due to the catalytic action of the specific organic polymer or the action of the gas passage. Is considered to be suppressed.

Since the fine pores are formed in this way, a SiO ₂ -based porous glass having a large number of fine pores with a narrow pore radius distribution can be obtained. At this time, if the dry gel is made to have the specific organic polymer uniformly dispersed as described above, the fine pores of the glass can be made to be uniformly dispersed.

Here, the heating temperature of the dry gel is set to 500 to 800 ° C., because the vitrification is insufficient at less than 500 ° C. and the strength and corrosion resistance are deteriorated, and above 800 ° C., after the removal of the specific organic polymer, This is because the pores are blocked and the porosity deteriorates.

As described above, the dry gel is heated at a temperature of 500 to 800 ° C. to be vitrified, so that the glass strength and the corrosion resistance can be improved as compared with the case of the conventional porous glass manufacturing method by the sol-gel method.

Since the micropores are formed by removing the specific organic polymer by heating the dry gel, the state of the micropores is determined by the formation conditions, that is, the gel heating conditions and the amount and type of the specific organic polymer, and controlling these conditions. Is extremely easy, and therefore it is easy to control the state of the fine pores of the glass (fine hole radius, specific surface area, etc.) and its reproducibility is excellent. In particular, it is possible to easily adjust the number of pores (specific surface area) by making the pore diameter almost constant by changing the addition amount of the specific organic polymer.

When the dry gel is heated, the pyrolytic carbon is discharged to the outside of the glass through the gas passage formed by the gasification of the specific organic polymer, so that it is difficult to remain and therefore, the steam treatment for a long time is not required. The blackening can be suppressed without doing so.

Therefore, according to the method for producing a SiO ₂ -based porous glass according to the present invention, it is possible to produce one having fine pores having a pore radius of about 5 to 10Å, and the conventional porous glass production by the sol-gel method. Compared with the method, the glass strength and corrosion resistance can be improved, and the state of glass micropores (particularly the specific surface area) can be easily controlled and has excellent reproducibility, and even without long-term steam treatment. It becomes possible to suppress the blackening of the glass.

When the dry gel is subjected to a steam treatment in which the temperature is gradually raised and heated in steam before heating the dry gel, the gel heating time becomes longer, but it is possible to reliably prevent glass blackening,
Also, since the specific surface area of the micropores can be increased,
Steam treatment may be performed if necessary.

When zirconium alkoxide is used as the alkoxide of metal other than silicon, it contains a large amount of ZrO _2.
This is preferable because it becomes a SiO ₂ -based porous glass and the alkali resistance can be greatly improved.

The specific organic polymer (one or more of polyethylene glycol, polypropylene glycol, polyacrylic acid, polyvinylpyrrolidone, polyvinyl alcohol) is an elongated micro substance having a length of about 5 to 20Å as described above. a (organic polymer), silicon alkoxide can be mixed uniformly in a solution containing also has a property of easily be removed by heating, mainly due to their obtained SiO ₂
In the porous glass, fine pores are uniformly dispersed.

The silicon alkoxide-containing solution and the other metal alkoxide-containing solution may contain an inorganic salt, if necessary. The other metal alkoxide-containing solution is not limited to one type of other metal, and may contain two or more types at the same time. Both solutions contain a solvent for the hydrolysis of the alkoxide, which alcohol and / or water can be used.

(Example) Example 1 Silicon ethoxide (hereinafter referred to as SE): 20.8 gr, molecular weight 60
0 polyethylene glycol (hereinafter PEG 600): 14.
6 gr (corresponding to 70 wt% with respect to SE), ethanol: alkoxide-containing solution (a) having an appropriate amount (a sufficient amount for phase-separated SE and PEG to be uniformly mixed), that is, a specific organic polymer at this blending amount Solution (a) in which PEG 600, which is one of the polyethylene glycols in the above, is dispersed in a solution containing SE which is one of the silicon alkoxides,
Water: 1.8 gr, ethanol: 4.6 gr, hydrochloric acid: 0.37 gr, a solvent for hydrolysis (b) and zirconium tetra-n-propoxide, which is one of zirconium alkoxides: 6.6.
A solution (c) that becomes gr and a hydrolysis catalyst (d) that becomes water: 3.6 gr, ethanol: 4.6 gr, and hydrochloric acid: 0.37 gr are prepared and prepared.

Then, the solution (a) of the above solvent (b) is slowly added with stirring, the mixture is stirred at room temperature for 1 hour, and then the solution (c) is added.
Was added and the mixture was stirred at room temperature for 1 hour, and then the solvent (d) was added.
Was added and stirred for 10 minutes. While keeping the mixture in a glass beaker, it was air-dried at room temperature while still standing.

After several weeks, the air-dried product (gel) was heated at 600 ° C. for about 10 hours to vitrify and PEG600 was removed to the outside of the glass.

For the SiO ₂ -based porous glass containing ZrO ₂ thus obtained, the specific surface area was measured by the BET method, and Gransto
When the pore volume and pore size distribution were determined by the n-Inkley method, the specific surface area of the micropores was 425 m ² / gr, and the micropore volume was 0.16.
cm ³ / gr, average micropore radius was about 6-9Å.

Further, the glass strength and the corrosion resistance were excellent as compared with the conventional porous glass manufacturing method by the sol-gel method.

Further, the glass was transparent and homogeneous without blackening.

Example 2 The amount (wt%) of PEG600 relative to SE in solution (a) was varied. Except for this point, a SiO ₂ -based porous glass containing ZrO ₂ was prepared in the same manner as in Example 1, and the distribution of the pore radius and the specific surface area were determined. The results are shown in Figs. 1 (a) and (b).
And (c) and FIG. FIG. 1 (a),
From (b) and (c), it can be seen that a sharp pore diameter distribution with an average pore radius of 10 Å or less is exhibited in any of PEG 600: 30, 50, 70 wt%. It can be seen from the curve (a) in FIG. 2 that the specific surface area increases as the amount of PE600 increases, although the pore size distributions are almost the same.

The curve (b) in FIG. 2 shows the result when steam treatment is performed before the gel heating, and the specific surface area is larger than that of the curve (a). It turns out to increase.

In addition to the above, using polyethylene glycols having different molecular weights in place of the PEG600, a SiO ₂ -based porous glass was prepared in the same manner as in Example 2, and the distribution of the pore radius and the specific surface area were determined. Results similar to those in Example 2 were obtained.

According to SiO ₂ based porous glass manufacturing method according to the present invention (Effect of the Invention), upon the production of SiO ₂ based porous glass by the sol-gel method, the pore radius having a 10Å about micropores In addition to being able to manufacture the sol-gel method, it is possible to improve glass strength and corrosion resistance as compared with the conventional method by the sol-gel method, and it is easy to control the state of glass micropores (micropore radius, specific surface area, etc.). The reproducibility is excellent, and the blackening of the glass can be suppressed without the steam treatment for a long time.

[Brief description of drawings]

1 (a), 1 (b), and 1 (c) are distributions of pore radii of the SiO ₂ -based porous glass according to Example 2, and FIG. 1 (a) shows Amount of PEG 600 added during the production of the glass: 3
Pore radius distribution in the case of 0 wt%, Fig. 1 (b) is the pore radius distribution in the case of PEG 600 addition amount: 50 wt%, Fig. 1 (c) is the PEG
FIG. 6 is a diagram showing a pore radius distribution in the case of 600 addition amount: 70 wt%. FIG. 2 is a diagram showing the relationship between the added amount (wt%) of PEG600 and the specific surface area of the obtained glass micropores according to Example 2. In addition, in FIG. 2, the curve (a) is shown when the gel is heated.
Is heated at 600 ° C. by a normal heating method, and the curve (b) is obtained by steaming the gel and then heating it at 600 ° C.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akiko Miyake, 2-4-15-403, Jonai-dori, Nada-ku, Kobe-shi, Hyogo Prefecture Examiner: Satoshi Hattori (56) Reference JP-A-61-17443 (JP, A) JP 62-123032 (JP, A)

Claims (3)

[Claims] 1. When producing a SiO ₂ porous glass by the sol-gel method, one or two selected from organic polymers such as polyethylene glycol, polypropylene glycol, polyacrylic acid, polyvinylpyrrolidone and polyvinyl alcohol. Regarding the solution obtained by dispersing the above organic polymer in a solution containing silicon alkoxide, the silicon alkoxide is hydrolyzed to form a sol, and then a solution containing an alkoxide of a metal other than silicon is added to and mixed with the sol. The alkoxide is hydrolyzed to form a sol and then gelled, which is dried to form a dry gel, which is heated at a temperature of 500 to 800 ° C. to vitrify and the organic gel in the dry gel is heated. By removing the molecule,
SiO ₂ system preparation of porous glass, characterized in that to obtain a SiO ₂ based porous glass having fine pores. 2. The method for producing a SiO ₂ -based porous glass according to claim 1, wherein the dry gel is subjected to steam treatment in which the temperature is gradually raised and heated in steam before the dry gel is heated. 3. The method for producing a SiO ₂ porous glass according to claim 1, wherein the metal alkoxide other than silicon is zirconium alkoxide.