JPH0222119A - Crystalline silicon oxide and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title silicon oxide giving a specific X ray diffraction pattern with little variation in granular size by calcination of spherical noncrystalline silica containing alkali metal fluoride and having each specified mean granular size and coefficient of variation of granular size. CONSTITUTION:Spherical noncrystalline silica 0.1-50mum in mean granular size and <=10% in coefficient of variation of granular size determined by the electrozone technique is prepared e.g., by hydrolysis of an alkoxysilane in a liquid reaction system comprising an alcohol and ammonia water. Thence, this noncrystalline silica is incorporated with an alkali metal fluoride (e.g., NaF, LiF) followed by calculation, thereby obtaining the objective spherical silicon oxide containing alkali metal fluoride, giving peaks in its X ray diffraction pattern (2theta=21.9 deg., 36 deg. and 31.5 deg.), 0.1-50mum in mean granular size, <=10% in coefficient of variation of granular size, suitable for e.g., carriers to be used in gas chromatography.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is characterized by the crystallinity of α-cristobalite, which exhibits an X-ray diffraction peak and has an extremely small variation in particle size, with an average particle size in the range of 0.1 to 5080 μm. This invention relates to silicon oxide and its manufacturing method.

(Prior Art and Problems to be Solved by TiA) A known method for crystallizing amorphous silica is to add sodium oxide, calcium oxide, etc. as a nucleating agent and then sinter it. However, when this method is applied to the crystallization of amorphous crystals with an average particle size in the range of 0.1 to 5060 μm and extremely small variation in particle size, although the particles are crystallized, the particles are sintered with each other during firing. In addition, the organosilicon compound is hydrolyzed in the presence of an alkali metal compound to obtain silica particles containing an alkali metal oxide. It is shown in JP-A-58-156526 that cristobalite can be obtained by firing. According to an electron microscopy examination of the particle size obtained by this method, the variation in particle size is small. However, when measured by the electrozone method, it was found that the above-mentioned particles exhibit a larger average particle size and particle size variation than those measured by electron microscopy. That is, it was found that sintering and aggregation of particles, which could not be confirmed by electron microscopy, could be confirmed by the electrozone method.

Therefore, the present inventors attempted to generate cristobalite by crystallizing amorphous silica, which has extremely small variation in particle size, by calcination. Research has been conducted with the aim of obtaining crystalline particles with extremely small variation in particle size while maintaining the shape of the raw material amorphous silica.

(Means for Solving the Problem) As a result, it was discovered that the above object could be achieved by using an alkali metal fluoride as a crystallizing agent for amorphous silica with extremely small variation in particle size, and the present invention was completed. I ended up letting it happen.

That is, the present invention contains an alkali metal fluoride, and in the X-ray diffraction pattern, 20 is 21.9°, 36.0', and 31.9°.
It has a peak around 5° and has an average particle diameter of 0.1 to 50.
It is made of spherical crystalline silicon oxide having a particle diameter of 0 μm and a coefficient of variation of particle diameter of 10% or less as measured by the electrozone method.

It can be confirmed by X-ray diffraction and differential thermal measurements that the crystalline silicon oxide of the present invention is mainly composed of α-cristobalite. For example, in the X-ray diffraction graph of crystalline silicon oxide, 20 is 21.9°.

It can be confirmed that the crystalline silicon oxide is composed of α-cristobalite since it has main peaks around 36.0° and 31.5°. Also, according to differential thermal analysis, α−
The fact that a peak indicating the transition between cristobalite and β-cristobalite is observed around 230° C. also confirms that the crystalline silicon oxide is composed of α-cristobalite.

The crystalline silicon oxide of the present invention contains an alkali metal fluoride.

The alkali metal fluoride is necessary for making the crystalline silicon oxide of the present invention have the X-ray diffraction/setane of α-cristobalite. As the alkali metal fluoride, LiF, NaF, KF, RbF, and CaF can be used without any restriction.

The content of alkali metal fluoride contained in the crystalline silicon oxide of the present invention is determined by the method for producing the crystalline silicon oxide,
Although it varies depending on the manufacturing conditions, in general, in order to obtain a spherical crystalline silicon oxide having the X@ diffraction pattern of α-cristobalite and to reduce the variation in particle size, the amount of Preferably, especially 0.5-5
Mol% is preferred.

In addition to the above-mentioned alkali metal fluoride, the crystalline silicon oxide of the present invention may contain oxidation of other metals as long as it does not adversely affect the variation in particle size or shape of the crystalline silicon oxide. It may contain things. Examples of oxides of other metals include oxides of metals in group Ⅰ of the periodic table such as magnesium oxide, calcium oxide, strontium oxide, and barium oxide; oxides of metals in group Ⅰ of the periodic table such as aluminum oxide Materials: Examples include oxides of metals in group Ⅰ of the periodic table, such as CR titanium, zorconium oxide, and hafnium oxide. In order to reduce the variation in the particle size of the crystalline silicon oxide and to maintain its spherical shape, the composition ratio of these metal oxides in the crystalline A raw silicon oxide particles should be 10 mol% or less. , preferably 5 mol% or less.

The shape, average particle diameter, particle size distribution, etc. of the crystalline silicon oxide of the present invention can be measured by observation using a scanning electron microscope and the electrozone method. The crystalline silicon oxide of the present invention has a particle size of 0.1 ttm to 50
ttm, preferably 2.0 fim to 15 μm
The particle size distribution is very narrow, and the coefficient of variation of the particle size measured by electrozone method is in the range of 0 to 10%, preferably in the range of 0 to 5%, and more preferably in the range of 0 to 3.
It can also be in the range of %.

Measurement of the coefficient of variation of particle size using the electrozone method is as follows:
Usually, this can be carried out using a Coulter Counter (manufactured by Coulter Electronics).

When the average particle diameter is less than 0.1 μm, the variation in particle diameter is large, and the coefficient of variation is 0 to 10% as specified in the present invention.
may not fall within the range. In addition, the average particle diameter is 50
．． Crystalline silicon oxide with a diameter exceeding 0 μm is not practical because it takes too much time to manufacture.

Furthermore, if the coefficient of variation of particle diameter exceeds 10%, the variation in particle diameter is too large, and therefore it cannot be used as a standard particle for measuring powder particle size or as a spacer for microelectronics such as liquid crystals, which will be described later.

The crystalline silicon oxide of the present invention has a smaller specific surface area than particles of general inorganic compounds, and is generally 0.01 to 50 m
/N range, usually 0.01-5m /,! It is the specific surface area in the range of i'.

Further, the crystalline silicon oxide of the present invention has a 10H group bonded to its surface. The amount of OH groups can be confirmed by measurement using an alkali neutralization method.

The crystalline silicon oxide of the present invention generally has an amount of 0.00001 to 15 mmol/O, depending on the specific surface area.
It has an OH group in the range of 9.

Furthermore, the specific gravity of the crystalline silicon oxide of the present invention cannot be expressed unconditionally because it varies depending on the composition ratio of silica and alkali metal heptide, but most commonly, the specific gravity is 2.00 to 2.00. Many are in the range of 2.40.

When using the crystalline silicon oxide of the present invention for applications where alkali metal fluorides are not desired, the crystalline silicon oxide of the present invention can be easily oxidized by contacting it with a mineral acid such as hydrochloric acid, sulfuric acid, or nitric acid. Fluoride content 0.1
It can be reduced to less than 100 ml. This acid treatment generally reduces the alkali metal fluoride content to 1100
It can also be set to 0 Pp or less, or even 100 ppm or less. In this case as well, the X-ray diffraction pattern, average particle size, coefficient of variation of particle size, and shape remain unchanged from before contact with the mineral acid.

Since the crystalline silicon oxide of the present invention has the above-mentioned properties, it can be used for various purposes, but the method for producing it is not particularly limited as long as it provides the above-mentioned properties. The most typical methods will be explained in detail below.

Contains alkali metal fluoride and has an average particle size of 0, 1 to 5
This is a method of firing spherical amorphous silica having a particle diameter of 0.0 μm and a coefficient of variation of particle diameter of 10% or less as measured by the electrozone method.

The spherical amorphous silica used as a raw material has an average particle diameter of 0.1 to 50.0 μm, and a coefficient of variation of the particle diameter measured by the electrozone method of 10 inches or less. Such spherical amorphous silica can be produced by a known method. For example, ethyl silicate [S amount (
A method of hydrolyzing alkoxysilanes such as C2H50)4] in a reaction solution consisting of alcohol and aqueous ammonia (Japanese Unexamined Patent Publication No. 156526/1983), a method of hydrolyzing alkoxysilanes such as C2H50)4] without substantially changing the concentration of ammonia. Examples include a method of hydrolyzing (Japanese Unexamined Patent Publication No. 62-52119), and a method of hydrolyzing alkoxy 7-rane in the presence of an alkali metal ion (% Japanese Patent Application Laid-Open No. 62-72516). If the amorphous silica obtained in this manner contains an alkali metal oxide, it may be sintered during the firing described later, resulting in large variations in particle size. For this purpose, a method is preferably employed in which the amorphous silica is brought into contact with a mineral acid to selectively elute the alkali metal oxide.

In this case, the concentration of alkali metal oxide is usually 1000
It is preferable to lower it to ppm or less.

The alkali metal heptafluoride contained in amorphous silica is
Those mentioned above can be used without any restriction. In addition, as a method for incorporating an alkali metal heptafluoride into amorphous silica,
When amorphous silica and an alkali metal fluoride are brought into contact with each other in an aqueous medium as described below, the alkali metal fluoride is dissolved in water to produce the alkali metal fluoride)fN aF 2. H
Compounds such as KF2 can also be used. Furthermore, an alkali metal fluoride can also be produced by reacting an alkali metal hydroxide and hydrofluoric acid in water.

The method of incorporating the alkali metal fluoride into the amorphous silica is not particularly limited, but, for example, a method of immersing the amorphous silica in an aqueous solution in which the alkali metal fluoride is dissolved is preferably employed.

Specifically, there is a method in which amorphous silica is immersed in an aqueous solution of an alkali metal fluoride and water is evaporated while stirring under heating. In this case, the concentration of the alkali metal fluoride in the aqueous solution is preferably selected so that the amount of the alkali metal fluoride described below is contained in the amorphous silica, and is generally in the range of o, oos to 1.0 mol/l. It is preferable to select . Further, the time and temperature for immersing the amorphous silica in the aqueous solution of alkali metal fluoride, the heating temperature for evaporating water, etc. are not particularly limited.

Also preferably employed is a method in which amorphous silica is immersed in an aqueous solution of an alkali metal fluoride to form a slurry, and then dried with a spray dryer.

In this case as well, it is preferable to determine conditions such as the slurry concentration so that the amount of alkali metal fluoride described below is contained in the amorphous silica.

The alkali metal fluoride of the present invention is contained in amorphous silica.
．． It is preferably contained in a range of 1 to 10 moles, particularly 0.5 to 5 moles.

The method for firing the amorphous silica containing the alkali metal fluoride obtained by the above operation is not particularly limited, and a known method may be used. For example, a box electric furnace, a tube furnace, etc. can be suitably used.

The atmosphere for firing may be air or an inert gas such as nitrogen or argon.

The firing temperature varies depending on the proportion of alkali metal fluoride contained in the amorphous silica, firing time, etc., so it cannot be determined generally, but it is in the range of 650 to 950°C, which is suitable for boat fishing. The temperature range is from 700 to 850°C.

The firing time varies depending on the proportion of alkali metal fluoride contained in the amorphous silica, the firing temperature, etc., and although it cannot be determined generally, it is 1 to 100 hours, preferably 5 to 100 hours. The range is 50 hours.

In this way, the crystalline silicon oxide of the present invention can be obtained.

(Effects) The present invention has succeeded in crystallizing raw material amorphous silica while maintaining its shape by adding an alkali metal heptadide to amorphous silica with a well-evened particle size. It is something.

The crystalline silicon oxide of the present invention does not cause sintering or agglomeration even when fired for crystallization, and has a particle size variation coefficient of 0 to 10 cm, preferably 0 to 51 cm, by electrozone method. It has an excellent value of 0 to 3 chi.

Moreover, since the crystalline silicon oxide of the present invention has an X-ray diffraction pattern of α-cristobalite, it has a higher coefficient of thermal expansion than amorphous silica.

The crystalline silicon oxide of the present invention having the above-mentioned characteristics is suitable for use as standard particles for electron microscopy and powder particle size measurement, as well as spacers for microelectronics such as immunology, clinical testing, and liquid crystals. Suitable for use as a carrier for liquid chromatography, gas chromatography, filter media evaluation tests, etc.

EXAMPLES The present invention will be described in more detail with reference to Examples below. Unless otherwise specified, measurements of various properties used in the Examples below were carried out as follows.

(1) Specific gravity Specific gravity was measured according to the pycnometer method.

(2) Particle shape and average particle size The shape of the particles and the state of agglomeration of the particles were observed using a scanning electron microscope. Moreover, the average particle diameter was determined by measuring the particle diameter of 100 arbitrary particles from a scanning electron microscope photograph, and was expressed as the number average.

(3) Average particle size and coefficient of variation of particle size Coulter
An arbitrary 100,000 particles were measured using a counter model TA-1u Hiniarthanereiday model 256 (both manufactured by Coulter Electronics), and the average particle diameter and the coefficient of variation of the particle diameter were determined. However, the coefficient of variation was calculated using the following formula.

However, the average particle diameter determined using a Coulter counter, xl indicates the first particle diameter, and n = 100.0
It is 00.

(4) Specific surface area Rapid surface area measuring device 5A-1 manufactured by Shibata Chemical Equipment Co., Ltd.
000 was used. The measurement principle is the BF, T method.

(5) Content of alkali metal fluoride Perchloric acid and hydrofluoric acid were added to a sample, distilled to dryness, dissolved by heating, and measured using an atomic absorption spectrometer.

Example 1 In a glass reactor with an internal volume of 51 and equipped with a stirrer, 160 methanol and aqueous ammonia (25% by market weight) were each added.
0- and 350 ml were charged and mixed well to prepare a reaction solution f4.

A raw material solution was prepared by dissolving 283,300 g of tetraethyl silicate [51 (OC2H5)4, manufactured by Nippon Colcoat Chemical Co., Ltd., trade name; ethyl silicate] in 11 parts of methanol. Similarly, an alkaline solution for addition was prepared by dissolving ammonia water (25 parts, 1 soo, p) in 11 parts of methanol.

Next, while keeping the temperature of the reaction solution at 20°C, the raw material solution was added at a rate of 12 d/min, while the alkaline solution for addition was added at a rate of 13 d/min.
d/min, and the concentrations of water and ammonia were in the range of 2.0 to 4.5 mol/if and 6.0 to 6.0 mol/if, respectively.
The reaction was carried out while maintaining the concentration within the range of 9.5 mol/l. About 20 minutes after the addition started, the reaction solution started to become cloudy.

Monodisperse spherical silica particles were produced about 40 hours after the start of the reaction. The silica particles were precipitated, the supernatant liquid was decanted, washed three times with methanol, and dried using a vacuum drier.

The particles had a true spherical shape and an average particle diameter of 2.45 μm when observed using a scanning electron microscope.

In addition, the average particle diameter measured with a Coulter counter is 2
．． At 43 μm, the coefficient of variation in particle size was 1.7%.

Furthermore, the results of X-ray diffraction confirmed that it was amorphous. The alkali metal content was below the detection limit (0.1 ppm) of atomic absorption spectrometry.

To the above amorphous spherical silica particles 30.0II.

A sodium fluoride aqueous solution consisting of 0.21N of sodium fluoride and 30.0# of water was added, and heated in a water bath with stirring to evaporate to dryness.

The obtained white powder was placed in an alumina tube and was heated at 10 min.
The temperature was raised from room temperature to 800°C at a rate of 10°C and held for 40 hours. Thereafter, the temperature was lowered from 800°C to room temperature at a rate of 2°C per minute to obtain a white powder.

As a result of observation using a scanning electron microscope, the powder thus obtained was found to be perfectly spherical in shape, with an average particle diameter of 2.
It was 42 μm. A photograph taken with a scanning electron microscope is shown in Fig. 2. Further, as measured by a Coulter counter, the average particle diameter was 2.41 μm and the coefficient of variation was 1.9 inches.

The average particle diameter determined by a scanning electron microscope and the average particle diameter measured by a Coulter counter were almost the same, confirming that no aggregation of particles due to sintering, etc. had occurred. .

The specific surface area of the obtained powder was 0.8 m2//9, the specific gravity was 2.29, and as shown in Fig. 1, the 2θ angle was 21.9°, 36°, θ° and 31.5
A series of peaks with a main peak at ° were observed, and it was confirmed that it was α-cristobalite. Further, as a result of atomic absorption spectrometry, NaF was found to be contained in an amount of 0.99 mol%.

Furthermore, the obtained powder 10.0. ! Add nitric acid aqueous solution (
3 mol/1) 300- was added thereto, heated to 90° C. with stirring, and held for 20 hours. Thereafter, it was thoroughly washed with distilled water and dried.

The sodium analysis value of the powder thus obtained was 12
ppm, and when measured with a Coulter counter, the average particle size and the coefficient of variation of particle size did not change at all from before the treatment with the nitric acid water bath. Specific surface area is 0.8
m 1g, specific gravity was 2.30. Further, the result of X-ray diffraction was the same as before treatment with nitric acid aqueous solution, and it was α-cristobalite.

Examples 2 to 6 The amorphous spherical silica particles shown in Example 1 (average particle diameter 2.43 μm>ft) were dispersed in a reaction solution of aqueous ammonia and methanol, and then added with aqueous ammonia and methanol. A raw material bath solution consisting of an alkaline bath solution, tetraenal 7 silicate [5L (C2H50)4], and methanol was slowly dropped into the above reaction solution to form spherical amorphous particles with the particle sizes shown in Table 1. 'f/I got Rika.

The alkali metal content of the silica particles thus obtained was all below the detection limit of atomic absorption spectrometry, and XIa diffraction showed that they were all amorphous.

Using these amorphous silicas, a crystalline silicon oxide was obtained in the same manner as in Example 1 except that the alkali metal fluoride and the calcined material were changed as shown in Table 1. The results were as shown in Table-1. The obtained particles are
By microscopic observation using a scanning electron beam analyzer, no agglomeration due to sintering or the like was observed, and the shape was perfectly spherical. Furthermore, since the average particle diameter determined by a scanning electron microscope and the average particle diameter measured by a Coulter counter are almost the same value, it is confirmed that no agglomeration due to sintering etc. has occurred. Sata@Example 7 Methanol, aqueous ammonia (25] if%) and 5N-Na were placed in a glass reactor (inner volume 51) equipped with a stirrer.
1600rrLt and 35Qm of OH aqueous solution, respectively.
1 and 8 ml were mixed well to prepare a reaction solution. Note that the sodium ion concentration was approximately 20 mmol/l.

Next, a raw material solution was prepared by dissolving tetraethyl silicate [5L (oC2H5)4, manufactured by Nippon Colcoat Chemical Co., Ltd., trade name: Ethyl silicate 28] in a ratio of 205.9 to 11 methanol.

In addition, methanol, aqueous ammonia (25% by weight) and 5N-NaOH aqueous solution were added at 700 t/each.

An alkaline solution for addition was prepared by mixing at a ratio of 200- and 100-.

While maintaining the temperature of the reaction solution at 20° C., the above raw material solution was added dropwise into the reaction solution at a rate of 1 m/min using a metering pump. Approximately 1° after starting addition of the raw material solution, the reaction solution began to become cloudy, and the concentration of IJium ions in the reaction solution gradually decreased. After about 2 hours after the addition started, the sodium ion concentration decreased to 5 mmol/l, and after this, the sodium ion concentration in the reaction solution was 5 mmol/l, and the water concentration was 7.0 to 8.5 mol/A. ! , the above alkaline solution for addition is added as appropriate until the reaction is stopped so that the concentration of ammonia becomes constant at 2.5 to 3.0 mol/7.
Added dropwise.

In addition, as a method to keep the sodium ion concentration in the reaction solution constant, measure the electrical conductivity in the reaction solution, and connect it to an electrical conductivity controller so that the electrical conductivity is constant at 0.6 ms/m. The alkaline solution for addition was intermittently added using a constant pump.

Approximately 30 hours after the start of the reaction, the particle size of the oxide particles in the reaction solution reached 3.0 μm, and the addition of the raw material solution and the alkaline solution for addition was stopped, the reaction solution was allowed to stand, and the oxide particles were allowed to settle. The supernatant was separated. Furthermore, after redispersing in methanol, performing decantation treatment, and washing,
Observation was made using a scanning microscope. As a result, the particles were completely spherical.

Particles obtained as above 50. F to methanol 1
600- and ammonia water (25wt%) 4001
The mixture was dispersed in a mixed solution of 100 ml to prepare a reaction liquid slurry.

In addition, methanol 800-, ammonia water (25 wt%
) 2001nt and 5N NaOH aqueous solution 10- were mixed to prepare an ammonia solution for addition. The raw material solution used had the same composition as the raw material solution described above.

Next, the ammonia solution for addition is added to the reaction liquid slurry.
It was added at a rate of 2 d/min, and after about 30 minutes, the raw solution was added at a rate of 1 rRt/min in parallel with the addition ammonia solution. Addition of the ammonia solution for acetic acid addition was continued until the reaction was stopped until the sodium ion concentration was 3.5 mm.
l/7s Water concentration is 7.5-8.5 mol//s Ammonia concentration is 2.5-3.0 mol/j! It was made to be constant.

The particle size of the oxide particles grew to 4.6 μm in about 48 hours after starting addition of the raw material solution. From a scanning electron micrograph,
The obtained oxide particles were completely spherical. Furthermore, when the above operation was repeated on two mice using the obtained particles with a particle size of 4.6 μm as seed particles, the particle size was 6.2 μm.
It became m. Thereafter, the reaction solution was allowed to stand, the oxide particles were allowed to settle, and the supernatant solution was separated. Furthermore, the mixture was redispersed in methanol, the decantation treatment was repeated three times, the methanol was removed using an evaporator, and the mixture was dried under reduced pressure at 120° C. to obtain oxide particles as a powder.

As a result of observation using scanning electron micrographs, the shape of the particles was perfectly spherical, and the average particle diameter was 6.23 μm. Furthermore, the average particle diameter measured with a Coulter counter was 6
．． At 22 μm, the coefficient of variation was 1.5%. According to the results of X-ray diffraction, it was found to be amorphous. Furthermore, the content of Na20 was found to be 6.8 mol% by atomic absorption spectrometry.

Obtained amorphous silica 30. 7+11 nitric acid aqueous solution (5 mol/A') was added to Og and stirred at room temperature for 15 hours. Thereafter, it was thoroughly washed with distilled water and dried.

The sodium content of the obtained particles was measured by atomic absorption spectrometry and was found to be 21 ppm. Further, as a result of X-ray diffraction, it was found to be amorphous.

To 15.0 g of the above amorphous spherical silica particles, 0.11 # of sodium fluoride and 20.0 g of water were added. An aqueous sodium fluoride solution consisting of O# was added and heated in a water bath while stirring to evaporate to dryness.

The obtained white powder was placed in a porcelain crucible, and the temperature was raised from room temperature to 750°C at a rate of 5°C per minute, and maintained for 20 hours. Thereafter, the temperature was lowered from 750°C to room temperature at a rate of 10°C per minute to obtain a white powder.

As a result of inspection using a scanning electron microscope, the powder thus obtained was found to be perfectly spherical in shape, with an average particle diameter of 6.
It was 20 μm. Also, according to Coulter counter measurement, the average particle diameter is 6.20 μm and the coefficient of variation is 1.8%.
De-) 7'C.

Since the average particle diameter determined using a scanning electron microscope and the average particle diameter measured using a Coulter counter matched, it was confirmed that no aggregation of particles due to sintering or the like had occurred.

The specific surface area of the obtained powder is 0.4 m2/, li',
The specific gravity is 2.30, and from the results of X-ray diffraction, 2θ
A series of peaks with main peaks at =21.9°, 36.0°, and 31.5° were observed, and it was confirmed that it was α-cristobalite. In addition, as a result of atomic absorption spectrometry, NaF
contained 1.04 mol%.

Next, the above crystallized powder 10. Og with nitric acid aqueous solution (
3 mol/1) 300- was added thereto, heated to 90° C. with stirring, and held for 20 hours. Thereafter, it was thoroughly washed with distilled water and dried.

The sodium value of the powder thus obtained was 28 p.
pm, and when measured with a Coulter counter, the average particle size and the coefficient of variation of particle size did not change at all from before the treatment with the nitric acid aqueous solution.

The specific surface area was 0.3 m /fi, and the specific gravity was 2.30. Further, the result of X-ray diffraction was the same as before treatment with nitric acid aqueous solution, and it was α-cristobalite.

Examples 8 to 10 11% O sulfuric acid and tetraethylsilicate [5l (OC2H5)4, manufactured by Nihon Colcoat Chemical Co., Ltd., trade name: Ethylsilicate 28] were mixed with 11% methanol at a ratio of 5g and 208g, respectively, This solution was then hydrolyzed at room temperature with stirring for about 2 hours. Thereafter, this was converted into tetrabutyl titanate (Tl(0-nC4H9)
4. Made by Japan Q4) 3. , i, p isozoro/reel 42
A mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate was prepared and used as a raw material solution.

All operations were performed in the same manner as in Example 7, except that the above raw material solution was used.

Furthermore, in the above operation, tetrabutyl titanate 3.
4. All procedures were carried out in the same manner as above except that P was changed to the raw material shown in Table 2. The results are shown in Table-2.

Comparative Example The amorphous silica obtained in Example 7 with an average particle diameter of 6.22 μm, a particle price variation coefficient of 1.5%, and a Na 20 content of 6.8 mol % was mixed with alumina-made Ruthenium silica. 10 per minute
The temperature was raised from room temperature to 900°C at a rate of 10°C and held for 20 hours. Then, the temperature was lowered from 900°C to room temperature at a rate of 2°C per minute to obtain a white powder.

As a result of X-ray diffraction analysis of the powder thus obtained,
A series of peaks with main peaks of gold were observed at 2θ-21.9°, 36.0° and 31.5°, and it was confirmed that it was α-cristobalite. Further, as a result of observation using a scanning electron microscope, the shape of the spherical particles was maintained and the average particle diameter was 6.21 μm. However, when measured with a Coulter counter, the average particle diameter was 37.26 μm.
, the coefficient of variation was 48.1%.

This indicates that the obtained particles maintain a spherical shape, but sintering occurs at the points of contact between the particles.

Furthermore, the obtained granules 10. OI! Add 300 - of nitric acid aqueous solution (3 mol//) to and heat to 90°C with stirring,
It was held for 0 hours. Then wash thoroughly with distilled water and dry.

The sodium analysis of the powder thus obtained was 8
The average particle size measured with a Coulter counter was 24.73 μm, and the coefficient of variation was 44.3%. Further, X-ray diffraction revealed that it was α-cristo-terolite, which was the same as before the treatment with the nitric acid water bath.

[Brief explanation of the drawing]

FIG. 1 shows the X-ray diffraction graph of the crystalline silicon oxide of the present invention obtained in Example 1. Indicates a turn. FIG. 2 is a molecular microscope photograph showing the morphology of the crystalline silicon oxide obtained in Example 1. Patent Applicant: Tokuyama Ichitatsu Co., Ltd. Procedural Amendment (Method) Date: October 1988

Claims (2)

[Claims] (1) Contains alkali metal fluoride, has peaks at 2θ in the vicinity of 21.9°, 36.0°, and 31.5° in the X-ray diffraction pattern, and has an average particle size of 0.1 to 50.0 μm. A spherical crystalline silicon oxide having a particle size variation coefficient of 10% or less as measured by an electrozone method. (2) Contains an alkali metal fluoride and has an average particle size of 0.
Claim (1) characterized in that spherical amorphous silica having a particle diameter of 1 to 50.0 μm and a variation coefficient of 10% or less as measured by an electrozone method is fired. A method for producing the crystalline silicon oxide described above.