JPS6033231A - Preparation of spherical porous glass - Google Patents

Abstract

PURPOSE:To prepare fine spherical porous glass by pulverizing glass contg. Na2O and B2O3, classfying the pulverized glass to specified size, heat-treating together with inorg. powder to spheroidize the glass and to separate the phases, and further treating with solution. CONSTITUTION:Na2O-SiO2 glass, Na2O-B2O3-SiO2 glass, or other glass contg. Na2O or B2O3 is prepd. by melting and then solidified by cooling. The pulverized glass after classifying and collecting 20-50mu particle size with a classifier is mixed with inorg. powder such as pulverous silica, carbon black, alumina, TiO2, etc. The mixture is heat-treated at 600-800 deg.C, and welding of semi-molten glass powder is prevented by the presence of said inorg. powder, and the glass powder is spheroidized by its surface tension, and the constitution of the glass is separated to different phases. The product is treated with HF previously to remove the thin SiO2 layer then treated with acidic or alkaline liquid to dissolved and remove the phase rich in Na2O and B2O3. Spherical porous glass is thus prepd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing spherical porous glass.

Porous glass has a sharp pore size distribution and is used as an inorganic functional porous material with a large specific surface area, such as various adsorbents, catalyst carriers, carriers for immobilized enzymes, and packing materials for gel permeation chromatography. It has an extremely wide range of applications, including materials for minute ms of generated gas in C1 chemistry.

Porous glass 1! The manufacturing method is, for example, American "1221
．． 5039, U.S. Patent No. 3,843,341, JP-A-57-1
Although it is described in No. 40334 etc., basically 1. Production of basic glass by mixing and melting raw materials; 2. Heat treatment for phase separation of glass structure, 3.820a min or Na2
3i by removing O-rich water-soluble layer or acid-soluble layer
02 Solution treatment with hot water, acid solution, alkaline solution, etc. to leave the rich layer as a porous skeleton; 4. The process consists of washing with water and drying. The porous glass obtained by the above method is generally crushed in shape.

When crushed porous glass is used, for example, in an adsorption column, it has drawbacks such as large pressure loss and low strength. However, such problems can be solved by using spherical porous glass, which has less pressure loss and higher strength than crushed porous glass. In order to obtain spherical porous glass, for example, a method for manufacturing general spherical glass can be applied. For example, 11II
For furnaces of II1 or higher, there is a method in which crushed glass is thrown into a rotary furnace together with coke, and for furnaces of 111 m or less, there is a method in which crushed glass is thrown into a combustion flame and collected together with combustion waste gas. However, this spheroidization must be carried out before the base glass is heat treated in the porous glass manufacturing process, and special equipment must be installed for this purpose.

The present invention was achieved as a result of various studies in view of the above-mentioned circumstances.The present invention has been achieved as a result of various studies in view of the above-mentioned circumstances.In the phase separation step by heat treatment of the basic glass, by making a special additive exist, heat treatment and spheroidization can be carried out at once. The present invention provides an efficient method for manufacturing spherical porous glass. That is, in the present invention, a basic glass obtained by mixing and melting raw materials for forming porous glass is heat-treated to phase-separate the structure, and then subjected to acid solution treatment, hot water treatment,
The gist of this invention is a method for producing spherical porous glass in which the heat treatment is carried out in the presence of inorganic powder when producing spherical porous glass by solution treatment such as alkaline solution treatment.

Hereinafter, the present invention will be explained in more detail. The spherical porous glass obtained by the method of the present invention has a basic composition of raw materials such as Na2O-8i02 system, Na2O-B2011
-8t 02 series, NazO-820a-AizOa-8
i Oz system, Na20-CaO-B20a-A sentence 20B
-8iO2 system, Na20-P20x-8i Oz system, N
It is made of az-820s-CeO2.3Nbz06 or the like.

Porous glass is made by using raw materials with the above composition as electricity.
It is a molten mixture obtained by heating with an electric current or an indirect heating furnace using heavy oil, gas, etc. as a heating source. The base glass is crushed into particles and the heat treatment conditions are e.g. 650-7.
The structure of the base glass is treated by maintaining it at 50°C for 12 to 24 hours, and the structure of the base glass is treated with NazO or B20B, which is soluble in acid solution or hot water.
The glass structure is created by dividing the phase into a phase mainly composed of the system and a phase mainly composed of other systems, and then solution-treated with an acid solution or hot water to elute the soluble component phase. Porous glass is created by forming pores inside the glass. In the method of the present invention, if the base glass becomes semi-molten during the heat treatment of the base glass, and the finely divided particles exist independently in that state, the finely divided glass particles themselves Spheroidization easily occurs due to surface tension, and if inorganic powder is present, the formed spherical particles will come into contact with each other and maintain their shape without causing welding, resulting in a spherical porous glass. This was reached based on the knowledge of Here, the inorganic powder is preferably one that does not decompose or melt at the heat treatment temperature of the base glass, and does not chemically react or eutectic with the glass. Furthermore, separation operations using sieves, elutriation classifiers, elutriation classifiers, etc. after heat treatment,
It is preferable to use a material that has a specific gravity and particle size different from that of glass and can be easily separated from glass. Representative examples of inorganic powders having such physical property conditions include finely powdered silica, carbon black, powdered alumina, and titanium oxide.

The basic glass subjected to heat treatment is usually coarsely crushed particles of about 1011 Il or less, but in order to obtain spherical porous glass by the method of the present invention, it must be further finely crushed and classified to a constant particle size before heat treatment. It is desirable to keep it. It is possible to obtain spherical porous glass with a sharp particle size distribution in high yield by pulverizing the particle size of the basic glass to a certain range and adjusting the classification before heat treatment. It is from. For crushing the basic glass before heat treatment, a crusher used for crushing general glass, ceramics, rocks, etc. can be used.1. For example, for coarse crushing, known show crusher mills, roller mills, etc. are used, and for fine crushing, ball mills, vibrating ball mills,
Fluid energy mill etc. are applied. Therefore, it is desirable that the pulverized particle size be 1 mm or less, preferably 100 μm or less. In addition, since the method of the present invention performs heat treatment by a static method, heat treatment and spheroidization can be performed simultaneously even for particles of about 1 to 5 μm, with almost no collection loss as in the case of spheronization of general glass. be able to.

Furthermore, in order to classify the ground base glass according to particle size as described above, a known JII classifier such as a gold wire sieve, a gravity classifier, a centrifugal classifier, an inertial classifier, or a flow classifier can be used. , a surface flow classifier, a classification method using a known elutriation classifier such as a Kuchi 11-de vortex classifier, and a classification method using various other sieving devices. The method of the present invention is characterized in that when the base glass, which has been refined and classified in advance as described above, is heat-treated to phase-separate the glass structure before heat treatment, an inorganic powder is present at the same time.

Here, the inorganic powder is one that does not decompose or melt under the heat treatment conditions of the base glass, and that does not react chemically with the glass.
Alternatively, one that is not eutectic is preferred. Furthermore, it is preferable to use a material that can be easily separated from glass by a separation operation using a sieve, elutriation classifier, elutriation classifier, etc. after heat treatment, and has a different specific gravity and particle size from glass. Representative examples of inorganic powders having such physical properties include finely powdered silica, carbon black, powdered alumina, and titanium oxide. Among these, when the specific gravity of the mixture is high, the glass particles become flat due to gravity under heat treatment phase separation conditions, so a pseudospherical powder with a high bulk specific gravity is preferable. From this, preferred examples of inorganic powders include finely powdered silica and carbon black, but carbon black colors the glass surface black and requires reheating to remove the coloration, which is troublesome. Therefore, fine powder silica is most suitable as the inorganic powder used in the method of the present invention. Therefore, as fine powder silica, there are those manufactured by a gas phase method such as Aerosil, those manufactured by a precipitation method from a solution such as White Carbon, and those manufactured by crushing silica gel. All of these are applicable. However, if the glass has a high water content, it will release water during heat treatment and co-resist with the boric acid in the glass component, so it is desirable to heat-treat and dehydrate it before use. Further, since finely powdered silicic acid containing many impurities such as Na1 is vitrified during heat treatment, it is desirable to perform acid treatment in advance to remove impurities.

When heat-treating the base glass, the pulverized base glass and the above-mentioned inorganic powder are mixed using a known mixer, for example, a type 2 mixer. The mixing ratio of the basic glass and the inorganic powder varies depending on the particle size of the finely ground basic glass, the particle size of the inorganic powder, and physical properties such as bulk specific gravity. If the mixing ratio of the base glass is too high, the formed spherical glass particles will come into contact with each other, forming a connected spherical glass, which is undesirable.
On the other hand, if the mixing ratio of the inorganic powder is large, the production rate of spherical glass will decrease, which is also undesirable. Therefore, it is necessary to determine the optimal mixing ratio in advance through small-scale experiments; in addition, since the finely ground basic glass becomes spherical and changes in particle size through heat treatment, in order to obtain porous glass with the desired particle size, In this method, the relationship between the particle size of the glass after heat treatment and the particle size of the pulverized base glass before heat treatment is investigated in advance, and the particle size of the pulverized base glass is selected based on this result. It is necessary. During the heat treatment of the base glass in the presence of inorganic powder, phase separation of the glass structure and simultaneous spheroidization occur when a mixture of the pulverized base glass and *It organic powder is placed in a furnace. , for example, by maintaining a temperature of 600 to 800° C. for 2 to 48 hours. Therefore, as mentioned above, during the heat treatment of the finely classified basic glass, if the basic glass becomes half molten, and in that state, the finely divided particles exist independently. Due to the surface tension of the pulverized particles themselves, spheroidization easily occurs, and due to the presence of the inorganic powder, the formed spherical particles maintain their individual shapes without coming into contact with each other and causing fusion. , a spherical glass with a phase-separated structure can be obtained.

In the IC spherical glass whose structure is phase-separated by the heat treatment as described above, it is necessary to separate the inorganic powder present at the same time during the heat treatment. The separation device is
The metal sieve, air elutriation classifier, water elutriation classifier, etc. mentioned above are used.

Spherical glass made of inorganic powder separated and phase separated,
Next, the acid solution in the tissue - Na2O and 820 soluble in hot water, etc.
A phase mainly composed of component i is eluted into a solution of acid solution, hot water, etc. to form pores in the tissue, and colloid-like substances that are produced by acid solution treatment and block the pores formed in the dish. Solution treatment with alkaline solution is performed to remove silica.
It is considered to be a spherical porous glass. When carrying out the above solution treatment, it is preferable that the spherical glass whose structure has been phase-separated by heat treatment is previously surface-treated with hydrofluoric acid. The reason for this is that when the spherical glass comes into contact with air during heat treatment, some of the boric acid on the surface evaporates, forming a layer with a high silicic acid content on the surface, which prevents the solution treatment from proceeding smoothly. This is because it is necessary to dissolve silicic acid. Acids used in solution processing include 80 sentences, HN O8, +12
Examples include organic acids such as free acetic acid such as S Oa and oxalic acid. Solution treatment with an acid solution or an alkaline solution is preferably carried out at a temperature of 50° C. or higher, for example. In addition, when the acid solution treatment is performed in several batches and the acid solution is replaced several times, the by-product of colloidal silica is reduced and the treatment efficiency is better. The same applies to the treatment with an alkaline solution, and specific operating methods thereof will be explained in Examples below. Examples of alkalis used include NaOH
, KOH1 lithium hydroxide, and the like.

After the liquid treatment, the spherical porous glass is washed in a basin and dried. For drying, heat transfer method, hot air drying, microwave method, etc. are applied, and the drying temperature is preferably 500°C or less, which causes little thermal denaturation of the obtained spherical porous glass and does not change the number of surface hydroxyl groups. A temperature of 100 to 200°C is desirable.

As described above, in the production of spherical porous glass, the present invention includes the presence of inorganic powder in the step of heat-treating and phase-separating the basic glass made of a molten Ia mixture of glass raw materials. By doing so, it is possible to obtain spherical porous glass, and the special equipment and operations for spheroidization can be omitted, making it possible to mass produce spherical porous glass useful as a column packing material, and its industrial use. It has great utility value.

Next, the present invention will be described with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Qa 0-8209-8i 02-AizOs glass with a composition ratio of Ca018%, 82011 17%, 5t
Oz 50%, Na20 5.59%, A120a
The raw materials lime, boric acid, silica sand, and alumina were mixed well to a concentration of 9.41% and placed in a glass melting crucible.
Calcinate and melt at 1100℃, then increase the temperature to 1350℃~1
The temperature was raised to 500°C and maintained for 4 hours to complete melting. This was either dropped into ice water and quenched, or cast into a mold and quenched to obtain a basic glass. This is a show crusher mill.
Subsequently, the mixture was coarsely crushed using a roll crusher mill, and then finely crushed using a fluidized bed counter jet mill (Alpine model) to an average particle size of 37 μm. The finely ground basic glass is classified using a known elutriation classifier such as a gravity classifier, centrifugal classifier, or inertial classifier, and the fraction particle size is 1.
It was fractionated into 0μ (fraction E), 10-20μ (fraction ■), 20-50μ (fraction I[[), and 50a or more (fraction IV). Next, 800 gr of Thyroid Grade 244 (product name of Fuji Davison Co., Ltd.: fine powder silica, hereinafter referred to as fine powder silica) as an inorganic powder was added to the fraction m 1 ko of the above, and mixed uniformly with a ■ type mixer. After that, remove the phase separation container (2
50Φ, made of 1200 iua 1 Sus310), and was heat-treated at 700° C. for 16 hours in a soaking electric furnace to phase-separate the glass structure and make it spheroidal. The spheroidized thermally heated glass is separated from finely powdered silica using an elutriation classifier similar to that described above, and is then subjected to a known elutriation classifier such as a full flow classifier, a surface flow classifier, or a Richard vortex classifier. The glass was classified using an elutriation classifier to obtain 850 or of spherical basic glass having a particle size of 20 to 40 μm. Next, put 8.5 liters of lN-80 into a Teflon thermostatic stirring container and adjust the temperature to 50°C.
After adjusting to 1N-HC!, the spherical base glass was added while stirring, and after stirring for 2 hours, it was left to stand, and by the gradient method, 1N-HC!
J. was eliminated. Put 1N-HO2, 5' Jiff, into the same container again, stir for 8 hours, and then add 1N-HO2, 5' Jiff.
After discharging C1, IN-H (,18,51) was put into the same container again, stirred for 14 hours, 1 H-HCl was discharged, and then washed with water several times by decanting method. Put 6fL of 0.5N-Na 0H into a container and set the temperature to 5.
After adjusting the temperature to 0°C, the spherical base glass treated with acid solution and washed with water was added while stirring, stirred for 2 hours, and allowed to stand still.
The 0°5N-NaOH was removed by the gradient method and the 0°5N-NaOH was removed again.
Put 5N-NaOHG polish in the same container and 108ejmFit
After washing, 0.5N Na OH was discharged, and then water washing was repeated by the decanting method until the washing liquid became neutral (p) (7). Then, IN-HCj15A was placed in the same container again and the temperature was adjusted to 50°C, then the spherical base glass treated with alkaline solution and washed with water was added and stirred for 3 hours. After that, water washing was repeated by the decanting method until the washing liquid was neutral. After washing until 180℃, the washing liquid was separated and heated to 180℃
4.3 Spherical porous glass by drying for 2 hours at
I got 0gr. In addition, 1% hydrofluoric acid was added in a Teflon-made ffi warm stirring vessel, and the temperature was adjusted to 20°C, and separately prepared lN-HCl and 0.5N-NaO were added.
) 850 g of spherical base glass before solution treatment with I
After adding R and stirring for 6 hours, leave to stand, remove 5% hydrofluoric acid by decanting method, and then wash with water several times to obtain a spherical base glass treated with hydrofluoric acid. IN-HC! in the same manner as the above operation example! L and 0°5N-NaO
Spherical porous glass 430 or
I got it. For these spherical porous glasses, the surface area was measured using a nitrogen adsorption method, the pore volume and average pore diameter were measured using a mercury intrusion porosimeter manufactured by Kalkuchi-Elva, and
The average particle diameter was measured using the Coulter counter method, and the shape was observed using an electron microscope.
Shown in the table. In addition, in the electron micrographs in FIGS. 1 to 4, in FIG. 1, 2.28c+a on the photo corresponds to 100μ, in FIG. 2, 1.514cm on the photo corresponds to 1μ, and in FIG. 3, 2.28c+a on the photo corresponds to 1μ. 26011 corresponds to 100μ, and in the photograph in FIG. 4, 1.0CI1 corresponds to 1μ.

Table 1 Example 2 Among the basic glasses obtained in Example 1, fractions separated by elutriation (fraction particle size of 10 μ or less > 1k
Add 700 or of finely powdered silica as an inorganic powder to
■After uniformly mixing with a type mixer, use a phase separation container (180
Φ, 1200 m11 (made of Sus310), and was heat-treated at 720° C. for 24 hours in a soaking electric furnace to effect both phase separation and spheroidization of the glass structure. The spheroidized heat-treated glass was subjected to elutriation classification and waterway classification similar to those in Examples to separate it from fine powder silica, and further waterway classification to obtain 920 or of spherical base glass having a particle size of 3 to 10 μm. Next, put IN-HCCO22& in a Teflon thermostatic stirring container and adjust the temperature to 50'C, then add the spherical base glass while stirring and after stirring for 2 hours, let it stand and remove IN-HCjl by the declination method. did. 1N-1-1c1 again
9.Pour 21 into the same container, stir for 8 hours, and add IN-HCA.
was discharged, 9.2 m of 1N-HCl was added again, and the mixture was stirred for 14 hours, and then washed with water several times by the decanting method. Next, 9.2jL of 0.5N-NaOH was put into the thermostatic stirring container, the temperature was adjusted to 50°C, and the spherical base glass treated with the acid solution and washed with water was added with stirring, stirred for 2 hours, and left to stand still. Then, 0.5N-NaOH was removed by the decanting method, 0.5N-NaO89,2A was added again, and the mixture was stirred for 10 hours. After that, washing with water was repeated by the decanting method until the washing liquid was neutral (DH'7). I washed it until clean. Next, after separating the washing liquid, it was dried at 180° C. for 2 hours to obtain spherical porous glass 5209r. In addition, 1 stand of 5% hydrofluoric acid was placed in a Teflon constant-temperature stirring container and the temperature was adjusted to 20°C, and separately prepared 1N-HCl and 0°5N-N
a Spherical base glass 92 before solution treatment with OH
After adding 0ar and stirring for 6 hours, the spherical base glass treated with hydrofluoric acid obtained by filtering with NO5G filter paper in Nutsche and washing with water several times was treated with 1N in the same manner as in the above operation example. -HC solution and 0.5N-NaOf-1 solution treatment, washing with water and drying to obtain 520 gr of spherical porous glass surface-treated with hydrofluoric acid. Physical property tests were conducted on these spherical porous glasses in the same manner as in Example 1. The results are shown in Table 2.

Table 2

[Brief explanation of drawings]

FIG. 1, FIG. 2, FIG. 3, and FIG. 4 show electron micrographs of the spherical porous glass obtained in Example 1. Agent: Patent attorney Tsutomu Sadatsu and 1 other person, TL Gekikuzu 2 Bokugo 3B $49

Claims (1)

[Scope of Claims] 1. A basic glass obtained by mixing and melting raw materials for forming porous glass is heat-treated to phase-separate the structure, and then subjected to solution treatment such as acid solution treatment, hot water treatment, alkaline solution treatment, etc. In producing the spherical porous glass, the heat treatment is carried out in the presence of an inorganic powder! IL construction method. 2. A method for producing spherical porous glass according to claim 1, wherein the base glass is classified into predetermined particle size ranges before heat treatment. 3 The inorganic powder is finely powdered silica, carbon black,
The spherical porous glass according to claim 1 or 2, which is made of one or more of zero-terminal alumina and titanium oxide! How to build. 4. Producing a spherical porous glass according to any one of claims 1 to 3, in which a base glass whose structure has been phase-separated by heat treatment is previously treated with hydrofluoric acid before solution treatment. how to.