JPH059381B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for manufacturing a spherical glass body.
More specifically, the present invention relates to a method for producing spherical glass bodies that are useful as column packing materials for various chromatographies and carriers for enzyme immobilization, as well as various industrial materials such as polymer filling reinforcing materials and gloss enhancers.

(b) Prior Art Conventionally, spherical glass bodies, particularly micro glass spheres, have been manufactured by dispersing a solution of sodium silicate in oil and gelling it, or by gelling it in dry air using a spray method. A method is known in which a spherical glass body made of oxide glass is obtained by subsequent heat treatment, but the process is complicated and takes a long time. On the other hand, it has been considered to form molten glass into a spherical shape, but this has been difficult to process in practice.

(c) Purpose This invention has been made in view of the above-mentioned conventional problems, and one object thereof is to provide a manufacturing method that allows a desired spherical glass body to be obtained in a simple process and in a short time. It is.

The present inventors focused on metal alkoxide, which is known as one of the raw materials for glass and ceramic production, and conducted research on a method for efficiently obtaining spherical glass bodies by utilizing its hydrolysis properties. As a result, they discovered that the presence of a small amount of hydrofluoric acid in the metal alkoxide hydrolysis system, which is normally carried out under acidic conditions, markedly accelerates water decomposition and can result in gelation in a short time. As a result of further research based on this, we have arrived at this invention.

(C) Structure According to the present invention, an aqueous solvent solution of a metal alkoxide containing a small amount of hydrofluoric acid is added at room temperature to an easily volatile liquid organic medium that is incompatible with the solution but is dispersible. A spherical glass characterized in that a metal alkoxide is hydrolyzed in a dispersed state by dispersing the metal alkoxide to form a spherical glass-like gel body, and if necessary, the glass-like gel body is subjected to a high-temperature heat treatment. A method for manufacturing a body is provided.

The metal alkoxide in this invention includes:
Various metal alkoxides known as raw materials in the glass manufacturing field and ceramic manufacturing field can be used, and specifically, Si(OCH ₃ ) ₄ , S(OC ₂ H ₅ ) ₄ ,
Ti( _{OC3H7 ) 4} , V _{( OC2H5} ) ₃ , Al _{( OC3H7} ) ₃ ,
Examples include lower alkoxy metals such as NaOCH ₃ ,
Among these, it is usually preferable to use lower alkoxysilanes. Note that a mixture of two or more of these may also be used.

As the aqueous solvent used for the aqueous solvent solution of the metal alkoxide, it is appropriate to use a volatile hydrophilic solvent containing water, such as aqueous methanol or aqueous ethanol. Moreover, the concentration of the aqueous solvent solution is not particularly limited. Since the spherical diameter of the spherical glass body is usually proportional to the viscosity of the solution, the concentration of the metal alkoxide may be determined so as to obtain a viscosity corresponding to the desired spherical diameter.

It is necessary that the amount of hydrofluoric acid contained in the solution is small. This small amount is
Expressed as a molar ratio to 1 mol of metal alkoxide, a suitable range is 0.1 to 1 mol. If the amount exceeds 1 mol, gelation occurs instantaneously during dispersion in an easily volatile organic medium, making it difficult to achieve sufficient dispersion, which is not preferred. Moreover, if the amount of hydrofluoric acid is too small, the time required for gelation is undesirable.

Note that, prior to the addition of hydrofluoric acid, an ordinary hydrolysis acid such as hydrochloric acid may be added to the aqueous solvent solution of the metal alkoxide. It is difficult to mix only the three components of alcohol and water, but mixing becomes easier with an acid. In the absence of an acid, a white precipitate is generated due to the reaction between the alkoxide and water, but this is preferable because it can be redissolved with an acid.

The aqueous solvent solution to which hydrofluoric acid has been added is rapidly dispersed into a liquid organic medium at room temperature. This organic medium is required to be incompatible with, but capable of dispersing, the hydrofluoric acid-containing solution.
In addition, "easily volatile" means that it can easily volatilize at room temperature or under heating up to about 150°C. As such an organic medium, an organic solvent that is hydrophobic and has a boiling point at room temperature of about 35 to 150°C is suitable, such as pentane, hexane, heptane, octawa, etc.
Examples include hydrocarbons having 4 to 10 carbon atoms such as cyclohexane, and aromatic hydrocarbons such as benzene, toluene, and xylene. However, even if it has a hydrophilic group, a substantially hydrophobic organic solvent can also be used, such as pentanols. Among these, those having a normal pressure boiling point of 100° C. or less are preferred, and it is particularly preferred to use cyclohexane or xylene.

Dispersion into the above organic medium is usually carried out by adding all at once and then stirring. At this time, the mixing volume ratio of the hydrogen fluoride-containing solution and the organic medium is
It is preferable to adjust the former so that it is 1/5 or less of the latter in terms of uniformity of the spherical glass body. In addition,
Stirring is preferably carried out using a stirrer or the like until the dispersed particles of the hydrogen fluoride-containing solution are gelatinized. The spherical diameter of the spherical glass body obtained can also be adjusted by this degree of stirring.

By dispersing the metal alkoxide in such an organic medium, hydrolysis of the metal alkoxide rapidly progresses in a dispersed state.
The dispersed particles transform into spherical glass-like gel bodies within a few minutes, and the spherical glass bodies of the present invention are obtained in a dispersed state.

The diameter of the formed spherical glass body depends on the viscosity of the metal alkoxide solution, the degree of stirring, etc. as mentioned above, but by adjusting these factors, it is possible to create large spheres with a diameter on the order of mm or micro spheres with a diameter on the order of μm. can be obtained as appropriate.

The spherical glass body thus formed is a porous glass-like gel body mainly composed of metal hydroxide compounds and/or condensates thereof, which are hydrolysates of metal alkoxides, and partially containing fluorine atoms. It consists of

These spherical glass bodies are put into practical use after being separated by volatilizing the organic medium on the spot or by separating and drying by mechanical means (for example, a filter).

This spherical glass body is subjected to high temperature heat treatment if necessary. For example, if an oxide glass sphere with the same quality as conventional silica glass is intended, the spherical glass body separated above is subjected to a high temperature heat treatment of 500°C or higher for a long time (for example, several hours) to achieve high condensation. All you have to do is turn it into The spherical glass bodies of the present invention made of these oxide glasses are useful as various industrial materials such as column packing materials for various chromatographies, various carriers, polymer filling reinforcing materials, and gloss increasing materials. On the other hand, the spherical glass bodies of the present invention that are not heat-treated or that are heat-treated at a high temperature of about 300°C or less are mainly composed of metal hydroxide compounds and low condensates thereof, and have a large number of hydroxyl groups and their reactivity. In addition to the above-mentioned uses, it is particularly useful as a support for immobilized biocatalysts, since the fluoride atoms have been introduced into the material.

Note that instead of the hydrofluoric acid used in this invention, a super strong acid containing hydrogen fluoride may be used.

(e) Example 1 mole of tetraethoxysilane Si (OC ₂ H ₄ ) ₄ was mixed with 3.8 mol, 3.6 mol, and 0.28 mol of water, ethyl alcohol, and hydrochloric acid, respectively, and vigorously stirred to form an aqueous solvent solution of tetraethoxysilane. I got it.
0.2 mol of hydrofluoric acid was added to this solution with stirring and mixed.

Then, this hydrofluoric acid-containing aqueous solvent solution
400 ml was added to 2000 ml of cyclohexane (in a beaker) and stirred vigorously with a stirrer (2500 rpm) to disperse the aqueous solvent solution phase. Stirring was continued, and after about 4 minutes, gelled spherical glass bodies were collected at the bottom of the beaker.

Next, this spherical glass body was filtered through a membrane filter to separate it from cyclohexane, washed with water, air-dried, and then dried at about 100°C.

The obtained spherical glass body was almost a perfect sphere with a diameter of approximately
It was a spherical body with a diameter of 50 μm. Further, by changing the rotation speed of the stirrer (1500 rpm), a true spherical body with a diameter of about 100 μm was obtained.

(f) Effects As stated above, according to the method of this invention,
Spherical glass bodies useful for various uses can be easily produced in a short time. Further, since the production can be carried out at room temperature and a volatile liquid organic medium is used, separation and cleaning of the formed spherical glass bodies is easy. Therefore, manufacturing costs can be significantly reduced compared to the conventional method.

Claims (1)

[Claims] 1 Hydrogenation of the metal alkoxide by adding and dispersing an aqueous solvent solution of the metal alkoxide containing a small amount of hydrofluoric acid in an easily volatile liquid organic medium that is incompatible with the solution but dispersible at room temperature. 1. A method for producing a spherical glass body, which comprises performing decomposition in a dispersed state to form a spherical glass-like gel body, and optionally subjecting the glass-like gel body to a high-temperature heat treatment.