JPH0524857B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing fine porous spherical silica particles having very uniform particle diameters and a large specific surface area. The fine particles can be used as adsorbents, catalysts, slipperiness improvers, solid lubricants, light diffusing agents, water repellents, thickeners, antifoaming agents, paints, rubber, resin and paper fillers, and column fillers for chromatography. It is useful as cosmetics, etc. [Prior Art and Problems to be Solved by the Invention] Conventionally, particles obtained by neutralizing alkali metal silicate with acid or hydrolyzable organosilicon compounds such as alkoxysilane are mixed with water, ammonia, or alcohol. A known method is to obtain porous spherical silica fine particles of a desired particle size by granulating spherical silica hydrate fine particles obtained by hydrolysis and condensation in a mixed solution of ing. In addition, an aqueous alkali metal silicate solution or a mixed aqueous solution of an alkali metal silicate and a hydrolyzable organosilicon compound having a silicon atom to which an organic group is directly bonded via its carbon atom is suspended in a nonpolar organic solvent. A method for obtaining porous spherical silica fine particles by adding the same to an acidic aqueous solution has also been disclosed (Japanese Patent Publication No. 15083/1983,
(Japanese Patent Application Laid-open No. 61-227913). However, the particle size distribution of the fine particles obtained by these methods is wide, and it is necessary to classify them to obtain porous spherical silica fine particles having a desired particle size, which poses problems in productivity and economy. On the other hand, it has been reported that porous spherical silica particles can be obtained by hydrolyzing and condensing a hydrolyzable organosilicon compound. For example, a method of hydrolyzing and condensing tetraethoxysilane in an ammoniacal hydroalcohol solution (Japanese Patent Application Laid-Open No. 62-72514
(No. 6), or a method of hydrolyzing and condensing a mixture of tetraethoxysilane and vinyltriethoxysilane (Proceedings of the 6th Inorganic Polymers Conference, No. 66)
~67 pages, 1987). However, when the inventors of the present invention examined the above-mentioned known method in detail, it was found that the particles dried at low temperatures do have a high surface area and are porous, but when heated at temperatures of 150°C or higher, the particles suddenly become porous. It was found that the surface area decreases with a concomitant loss of porosity. That is, the above-mentioned known techniques have a problem in that stable porous spherical silica fine particles having heat resistance cannot be obtained. [Means for Solving the Problems] The present inventors have solved the problems in the conventional methods described above, and have created porous spherical silica fine particles with very uniform particle diameters, a large specific surface area, and heat resistance. As a result of extensive research on a method for manufacturing reproducibly and inexpensively, we found that after bonding the silanol groups of spherical silica hydrate particles with an alcohol (hereinafter referred to as alcohol (A)) with a boiling point of 120°C or higher at normal pressure. The present inventors have discovered that such porous spherical silica fine particles can be obtained by drying or firing, and have proposed the present invention. That is, the present invention involves hydrolyzing and condensing a hydrolyzable silicon compound in an organic solution containing water to form spherical silica hydrate fine particles, and drying and/or calcining the spherical silica hydrate fine particles. In the method for producing spherical silica fine particles, the spherical silica hydrate fine particles are heated in the presence of an alcohol having a boiling point of 120° C. or higher at normal pressure to bond with the alcohol before drying and/or calcination. After that, the drying and/or calcination is carried out at a temperature of 200°C _{to 1000 °} C. Indicates the average composition of organic groups having atoms, n is 0 to 1
Each number represents a range of numbers. ) This is a method for producing porous spherical silica fine particles expressed as follows. In addition, silica as used in the present invention is defined as an oxygen-containing silicon compound in which silicon atoms constitute a three-dimensional network mainly through bonds with oxygen atoms, and as shown in the general formula (), This also includes the case where an organic group (R) is partially bonded directly to the silicon atom therein. In addition, porous as used in the present invention refers to S ^x d (m) and 〓 respectively represent the particle density (g/m ³ ).) The following relationship is satisfied. For reference, in the case of a non-porous true spherical fine particle whose particle surface is smooth without irregularities and has no voids, there is a relationship of S×d×〓=6. The method of the present invention will be explained in detail below. The hydrolyzable silicon compound, which is a raw material for producing the porous spherical silica fine particles of the present invention, is not particularly limited as long as it can be hydrolyzed to form a hydrate; As a simple and inexpensive one, the general formula () R′ _n SiX _4-n (where R′ is an alkyl group with up to 10 carbon atoms which may have a substituent, an aryl group, an unsaturated aliphatic residue) (X represents at least one group selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, and an acyloxy group, and m represents an integer in the range of 0 to 3.) Silane compounds and derivatives thereof are preferably used. Specific examples of these include chlorosilane compounds such as tetrachlorosilane, methyltrichlorosilane, phenyltrichlorosilane, dimethyldichlorosilane, diphenyldichlorosilane, methylvinyldichlorosilane, trimethylchlorosilane, and methyldiphenylchlorosilane; tetramethoxysilane; Ethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, trimethoxysilane, triethoxysilane, methyltrimethoxysilane, trimethoxyvinylsilane, triethoxyvinylsilane, 3-
Glycidoxypropyltrimethoxysilane, 3-
Chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-(2-aminoethylaminopropyl)trimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydimethylsilane, dimethoxymethylsilane, diethoxy Methylsilane, diethoxy-3-glycidoxypropylmethylsilane, 3-chloropropyldimethoxymethylsilane, dimethoxydiphenylsilane, dimethoxydimethylphenylsilane, trimethylmethoxysilane, trimethylethoxysilane, dimethylethoxysilane, dimethoxydiethoxysilane, Alkoxysilane compounds such as tetraacetoxysilane, methyltriacetoxysilane, phenyltriacetoxysilane, diacetoxydimethylsilane, diacetoxymethylsilane, acetoxytrimethylsilane, acyloxysilane compounds such as diphenylsilanediol, trimethylsilanol, etc. Examples include silanol compounds. Among these, alkoxysilane compounds are easily available as raw materials,
When made into fine particles, there is no contamination with halogen, etc., which is preferable. Among them, when a methoxysilane compound and/or its derivative is used as the main raw material, the specific surface area of the obtained porous spherical silica particles increases significantly and S×
It exhibits porosity reaching d×〓>100,
It is a particularly preferred raw material. Further, as other hydrolyzable silicon compounds, there are derivatives of the above-mentioned silane compounds. An example is a compound in which some of the hydrolyzable groups (X) are substituted with a group that can form a chelate compound, such as a carboxyl group or a -dicarbonyl group, or a compound in which these silane compounds or chelate compounds are partially hydrolyzed. There are low condensates obtained by Furthermore, the spherical silica fine particles are made of a silane compound represented by the above general formula () and/or
The main raw material is sodium, potassium, rubidium, cesium, magnesium,
The raw material may be one in which organic metal compounds or inorganic salts such as calcium, strontium, barium, boron, aluminum, gallium, and indium are coexisting. In this case, it is preferable that the proportion of silicon be 70% or more in terms of atomic ratio. The above-mentioned hydrolyzable silicon compounds can be used alone or in combination as a raw material. However, when only a silane compound and/or its derivative in which m in the general formula () is 2 or 3 is used as a raw material, the spherical silica fine particles of the present invention cannot be obtained. The above-mentioned raw material hydrolyzable silicon compound is hydrolyzed and condensed in an organic solution containing water. Hydrolysis can be carried out by any method such as batch, divided, continuous, etc. When hydrolyzing,
Catalysts such as ammonia, urea, ethanolamine, and tetramethylammonium hydroxide may also be used. Here, the organic solution refers to a solution in which water and a catalyst are completely dissolved in an organic solvent capable of dissolving a silicon compound as a raw material, or a solution in which water and a catalyst are uniformly dispersed as micelles in an organic solvent. Specific examples of the organic solvent include methanol, ethanol, isopropanol, n-butanol, t-butanol, pentanol, ethylene glycol,
Alcohols such as propylene glycol and 1,4-butanediol, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, (cyclo)paraffins such as isooctane and cyclohexane, ethers such as dioxane and diethyl ether, benzene , aromatic compounds such as toluene, etc. may be used alone or in combination. In the case of organic solvents that are not compatible with water or catalysts, a surfactant may be added to them to form uniform micelles. When hydrolyzing and condensing raw material silicon compounds, the amount of water and catalyst present must be controlled to a preferable amount because it affects the particle shape, particle size, and dispersion state. The concentration of the catalyst is 0.1 to 50 mol/liter, respectively.
It is preferable to adjust it within the range of ~10 mol/liter. These can also be added in portions depending on the addition of the raw material silicon compound. Hydrolysis and condensation can be carried out by adding, for example, the above-mentioned raw material hydrolyzable silicon compound or its organic solvent solution to the above-mentioned organic solution, and heating at a temperature of 0 to 100°C, preferably 0 to 70°C, for 30 minutes to 100 hours. This is done by stirring. In this way, by hydrolyzing and condensing the raw material hydrolyzable silicon compound in an organic solution containing water under appropriate conditions, hydrate particles with a spherical shape and a very sharp particle size distribution are formed. It precipitates and becomes a suspension. Next, the spherical silica hydrate fine particles thus produced are heated in the presence of an alcohol (A) having a boiling point of 120° C. or higher at normal pressure to bond the silanol groups on the surface of the fine particles with the alcohol (A). Alternatively, alcohol (A) is present from the step of hydrolyzing and condensing the silicon compound to hydrolyze and condense the silicon compound to generate spherical silica hydrate fine particles, and the alcohol (A) is added to the spherical silica hydrate fine particles. A) may be combined. Examples of preferable alcohols (A) include monohydric alcohols having 5 or more carbon atoms that dissolve in any proportion with water, dihydric alcohols such as ethylene glycol, propylene glycol, and diethylene glycol, polyhydric alcohols such as glycerin, and polyhydric alcohols such as glycerin. Examples include polymeric alcohols such as glycol and polyvinyl alcohol. Furthermore, an alcohol having a functional group such as an amino group or a carboxyl group and having a boiling point of 120° C. or higher at normal pressure can also be used.
Alcohols with boiling points below 120°C at normal pressure have little effect on porosity. Further, the higher the boiling point of alcohol (A), the smaller the amount of bound alcohol (A) and the more porous spherical silica particles having a higher specific surface area can be obtained. Furthermore, even if the boiling points are about the same, dihydric alcohols can produce more porous spherical silica particles with a larger specific surface area than monohydric alcohols, and polyhydric alcohols can produce porous spherical silica particles with a larger specific surface area even with a smaller amount added than dihydric alcohols. , dihydric alcohols such as propylene glycol, diethylene glycol, and triethylene glycol, and polyhydric alcohols such as glycerin are preferably used because they have great effects, are inexpensive, and are easily available industrially. The amount of alcohol (A) may be such that the alcohol (A) can bind to the spherical silica hydrate fine particles, but preferably the spherical silica hydrate fine particles are
1 alcohol (A) per 1 g of dry weight at 200℃
The amount is required to be at least 1 mmol, more preferably at least 10 mmol. Various methods can be used to bind alcohol (A) to the surface of silica hydrate fine particles. For example, (1) a method in which the fine particles are separated from an organic solution suspension of the hydrate fine particles by centrifugation, filtration, etc., and then the fine particles are sufficiently impregnated with alcohol (A) and heated. (2) A method in which alcohol (A) is added to an organic solution suspension or its concentrate, and then the fine particles are separated and heated. (3) A method in which a part or all of the organic solution in an organic solution suspension or its concentrate is replaced with alcohol (A) under heating, thereby serving as both solvent replacement and heating. (4) A method in which a part or all of the organic solution in an organic solution suspension or its concentrate is replaced with alcohol (A) as a solvent and then heated. etc., but the method is not limited to the above method. The heat treatment is preferably performed at a temperature of 50°C or higher. By doing so, the amount of alcohol (A) bound can be made to be 0.1 mmol or more, preferably 0.3 mmol or more, per 1 g of the weight of the spherical silicate fine particles dried at 200°C, and a high ratio. It has a surface area, is heat resistant, and S×d×〓>
Porous spherical silica fine particles up to 100% can be obtained. The heat treatment is more preferably carried out at a temperature of 100°C or higher and lower than the boiling point of alcohol (A) under the operating pressure. Further, the heat treatment may be performed under reduced pressure, normal pressure, or increased pressure, and may be accompanied by evaporation and distillation of the organic solution. In this way, the spherical silica hydrate particles are bound to the alcohol (A), but it is important that the alcohol (A) be present on the particle surface at least at the point where the silanol groups of the hydrate particles can undergo dehydration condensation. It is. It is thought that by doing so, a bonding reaction between the silanol groups and the alcohol (A) occurs and dehydration condensation between the silanol groups is suppressed. If heat treatment is performed without binding alcohol (A), dehydration condensation of the silanol groups on the surface of the fine particles will easily proceed, the specific surface area will rapidly decrease, and at the same time, the porosity will disappear. Next, the obtained spherical silica particles bound with alcohol (A) were heated at 200°C or higher for 1000°C.
Preferably bound alcohol at a temperature below °C
Porous spherical silica fine particles are obtained by drying and/or firing at a temperature above the decomposition temperature of (A) and below 1000°C. The bond decomposition temperature of alcohol (A) varies depending on the alcohol (A) and the firing atmosphere, but a temperature of 200°C or higher is required. If the decomposition is incomplete, the carbide of alcohol (A) will remain, blocking the pores and reducing the specific surface area, so it is preferable to fully decompose it. The decomposition temperature of bound alcohol (A) can be easily determined by differential thermal analysis.
When the spherical silica fine particles bound to alcohol (A) are a suspension containing alcohol (A), they are isolated by filtration, centrifugation, vacuum concentration, etc., or are calcined at the same time as isolation. Furthermore, if the spherical silica fine particles bound with alcohol (A) are powder, they are fired as they are. [Effects of the Invention] According to the present invention, a specific alcohol (A ), a porous spherical shape with a sharp particle size distribution, a high specific surface area, and heat resistance that does not lose its porosity even after drying and/or firing. Silica fine particles can be obtained. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by these Examples. In addition, the shape, average particle diameter, standard deviation value, specific surface area,
The true specific gravity, amount of bound alcohol (A), and amount of bound organic groups were analyzed and evaluated by the following methods. - Particle shape Determined by electron microscope observation at 50,000x magnification. - Average particle size and standard deviation value The particle size of 300 arbitrary particles in an electron microscope image taken at a magnification of 50,000 times was actually measured and determined using the following formula. Standard deviation value = d + 〓 _o-1 / d - Specific surface area (measurement of S) The specific surface area was measured by the BET method. - True specific gravity (measurement of 〓) True specific gravity was measured using a Shimadzu autopycnometer 1320. - Amount of bound organic groups (measurement of n) A suspension after binding alcohol (A) and silanol groups, or a part of the alcohol (A) suspension.
Vacuum dry at 50°C to completely remove volatile components such as solvent to obtain a fine powder sample. Approximately 5 g of the obtained powder sample is accurately weighed, added to 250 ml of 0.05N aqueous sodium hydroxide solution, and stirred at room temperature for 10 hours. As a result, all the hydrolyzable groups in the fine particles are hydrolyzed and extracted into an aqueous solution. The fine particles in the suspension were separated by ultracentrifugation, washed repeatedly with water, and then dried at 200°C for 5 hours. The total carbon content of the fine particle powder sample was measured by elemental analysis, and the total carbon content was determined from the R′ _n SiX ₄ used as the raw material. n was determined by calculating R in the general formula () from the average carbon number of m R's of _-n . On the other hand, FT-IR reveals the

The bond of [Formula] was also confirmed. - Amount of bound alcohol (A) When measuring the amount of bound organic groups, the amount of alcohol (A) in the clear liquid in which the hydrolyzable groups are hydrolyzed and extracted and the fine particles are separated from the aqueous solution is quantified by gas chromatography. After drying at 200°C for 5 hours, the amount of bound alcohol (A) per 1 g of fine particles was determined. Example 1 In a 2-liter glass reactor equipped with a stirrer, a dropping port, and a thermometer, 3 g of ethanol 707, 275.3 g of 28% aqueous ammonia, and 24.0 g of water were added and mixed.
The temperature of the organic solution was adjusted to 30±0.5°C, and 134.1 g of tetraethoxysilane was added dropwise from the dropping port over 1 hour while stirring. Stirring was continued for 1 hour after dropping to perform hydrolysis and condensation, resulting in spherical silica water. hydrate fine particles (1
-A suspension of a) was obtained. At this time, the concentration of each raw material relative to the total amount of the final solution was 0.47% for tetraethoxysilane.
mol/liter, water 9.01 mol/liter, and ammonia 3.31 mol/liter. On the other hand, there is a 1 liter glass evaporating pot equipped with a stirrer that can be heated by a heating medium from the outside, a dripping port, a thermometer, and a distillate gas outlet, a distillate gas condenser, a vacuum suction port, and a condensing gas outlet. Pour 300 g of ethylene glycol into the evaporator of the evaporator, which consists of a liquid receiver, and bring the system to normal pressure while stirring to maintain the heating medium temperature.
The temperature was set at 120°C. Next, the suspension obtained earlier is continuously supplied from the dripping port, and the alcoholic solvent containing ethanol, water, ammonia, and a small amount of ethylene glycol is distilled out, and after the supply of the suspension is finished, the heating medium temperature is lowered. The temperature was set at 230° C. and heating was continued for 5 hours at the boiling point of ethylene glycol to perform solvent replacement and ethylene glycol bonding treatment to obtain an ethylene glycol suspension of spherical silica fine particles (1-b). Next, a part of the suspension was collected and bound ethylene glycol was quantified, followed by concentration under reduced pressure at 90°C using an evaporator to remove ethylene glycol. The obtained powder was fired at 600°C to produce porous spherical silica fine particles (1). The analysis results are shown in Table 2. Examples 2 to 4 Reaction conditions such as the type of silane compound or its derivative, composition ratio, type of organic solvent, concentration of each raw material with respect to the total amount of final solution, reaction temperature, type of alcohol (A), and calcination temperature are shown in Table 1. Porous spherical silica fine particles (2 to 4) were produced in the same manner as in Example 1 except that the procedures were as shown. The analysis results are shown in Table 2. Example 5 200 g of ethylene glycol was added to the suspension of spherical silica fine particles (1-a) obtained in Example 1, and the suspension was concentrated using an evaporator without reducing the pressure. When the internal temperature reached 120°C, Heating was continued for 1 hour to perform ethylene glycol bonding treatment. A portion of the resulting suspension was collected, the amount of bound ethylene glycol was determined, and then concentrated under reduced pressure at 80°C to remove liquid phase components. The obtained powder was fired at 500°C to produce porous spherical silica fine particles 5. The analysis results are shown in Table 2. Example 6 The suspension of spherical silica microparticles (1-a) obtained in Example 1 was centrifuged at room temperature to isolate spherical silica hydrate microparticles (6-a). At this time, the liquid phase component was not completely removed and the particles remained wet. After adding 100 g of propylene glycol to the spherical silica hydrate fine particles and performing ultrasonic dispersion, the mixture was concentrated under reduced pressure at 70°C using an evaporator and subjected to propylene glycol bonding treatment to obtain spherical silica fine particles. A part of the obtained spherical silica fine particles was collected and the amount of bound propylene glycol was determined, and then the remaining spherical silica fine particles were calcined at 400°C to produce porous spherical silica fine particles (6). Table 2 shows the analysis results.
Shown below. Example 7 383.2 g of ethanol, 275.3 g of 28% aqueous ammonia, 24.0 g of water, and ethylene glycol were placed in a 2-liter glass reactor equipped with a stirrer, a dropping port, and a thermometer.
300g was added and mixed. Add the organic solution to 30±
While adjusting the temperature to 0.5℃ and stirring, a solution of 134.1 g of tetraethoxysilane diluted with 110.0 g of ethanol was added dropwise from the dropping port over 1 hour. Stirring was continued for 1 hour after dropping to perform hydrolysis and condensation, resulting in spherical silica water. A suspension of hydrate fine particles was obtained. At this time, the concentration of each raw material relative to the total amount of the final solution is tetraethoxysilane.
The concentrations were 0.47 mol/liter, water 9.01 mol/liter, ammonia 3.31 mol/liter, and ethylene glycol 3.53 mol/liter. Next, the suspension was heated to an internal temperature of 120° C. to distill off low-boiling components and subjected to ethylene glycol bonding treatment to obtain an ethylene glycol suspension of spherical silica fine particles. After quantifying the amount of bound ethylene glycol, ethylene glycol was removed in the same manner as in Example 1, and the resulting powder was fired at 600°C to produce porous spherical silica fine particles (7). The analysis results are shown in Table 2. Example 8 10 g of spherical silica hydrate fine particles (6-a) obtained by centrifugation in Example 6 was dissolved in glycerin.
After adding it to 10 g and performing ultrasonic dispersion, it was placed in a magnetic crucible. This was placed in an electric furnace set at 300°C and subjected to glycerin bonding treatment while flowing nitrogen to remove excess glycerin. A part of the obtained spherical silica fine particles was collected and the amount of bound glycerin was quantified. The remaining spherical silica particles were heated to 900℃.
Porous spherical silica particles (8) were produced by firing.
The analysis results are shown in Table 2. Example 9 After adding 933 ml of methanol and 100 g of 28% ammonia water to a 2-liter glass reactor equipped with a stirrer, a dripping port, and a thermometer, ammonia gas was further blown in to absorb and mix 17 g. Ammonia concentration was adjusted. The organic solution was adjusted to 10 ± 0.5°C, and while stirring, a solution prepared by diluting a mixture of 81 g of tetramethoxysilane and 53 g of phenyltrimethoxysilane in 133 ml of methanol was added dropwise from the dropping port over 1 hour.
After the dropwise addition, the internal temperature was raised to 50° C., and stirring was continued for 5 hours for ripening, hydrolysis and condensation to obtain a suspension of spherical silica hydrate particles. At this time, the concentrations of each raw material relative to the total amount of the final solution were: 0.40 mol/liter of tetramethoxysilane, 0.20 mol/liter of phenyltrimethoxysilane,
Water was 3.0 mol/liter and ammonia was 2.0 mol/liter. Next, porous spherical silica fine particles (9) were produced in the same manner as in Example 1, except that the type of alcohol (A) and the firing temperature were as shown in Table 1. The analysis results are shown in Table 2. Examples 10 to 16 Reaction conditions such as the type of silane compound or its derivative, composition ratio, type of organic solvent, concentration of each raw material with respect to the total amount of final solution, reaction temperature, type of alcohol (A), and calcination temperature are shown in Table 1. Porous spherical silica fine particles (10 to 16) were produced in the same manner as in Example 9 except that the procedure was as shown in Example 9. The analysis results are shown in the table. Comparative Example 1 Spherical silica hydrate fine particles (6)-a obtained in Example 6 were dried under reduced pressure at 100°C to produce spherical silica fine particles (17). The analysis results are shown in Table 2. Comparative Example 2 A suspension of spherical silica fine particles in n-butanol was obtained in the same manner as in Example 1, except that n-butanol was used instead of ethylene glycol and the final temperature was 117°C. After quantifying the amount of bound n-butanol, n-butanol was removed in the same manner as in Example 1, and the resulting powder was calcined at 600°C to produce spherical silica fine particles (18). The analysis results are shown in Table 2. Comparative Example 3 Spherical silica fine particles obtained in Comparative Example 1 (17)
After adding 30g to 300g of ethylene glycol and ultrasonic dispersion,
Heating was continued for a period of time to obtain an ethylene glycol suspension of spherical silica particles. After quantifying the amount of bound ethylene glycol, ethylene glycol was removed in the same manner as in Example 1, and the resulting powder was fired at 400°C to produce spherical silica fine particles (19). The analysis results are shown in Table 2. Comparative Example 4 Ethylene glycol was removed from the ethylene glycol suspension of the spherical silica fine particles (1-b) obtained in Example 1 in the same manner as in Example 1,
The obtained powder was fired at 1200°C to produce spherical silica fine particles (20). The analysis results are shown in Table 2. Comparative Examples 5 and 6 Example 9 except that the reaction conditions such as the type of silane compound or its derivative, the composition ratio, the type of organic solvent, the concentration of each raw material with respect to the total amount of the final solution, and the reaction temperature were as shown in Table 1. A suspension of spherical silica hydrate fine particles was obtained in the same manner as above. Subsequently, the resulting suspension of spherical silica hydrate fine particles was concentrated under reduced pressure at 50° C. using an evaporator to distill off the organic solvent, water, and ammonia. The obtained powder was calcined at 350℃ to obtain spherical silica particles (21,
22) was manufactured. The analysis results are shown in Table 2.

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Claims (1)

[Claims] 1. A hydrolyzable silicon compound is hydrolyzed and condensed in an organic solution containing water to form spherical silica hydrate fine particles, and the spherical silica hydrate fine particles are dried and/or In the method of producing spherical silica fine particles by firing, the spherical silica hydrate fine particles are heated in the presence of an alcohol having a boiling point of 120°C or higher at normal pressure to combine with the alcohol before drying and/or firing. After drying, the drying and/or calcination is carried out at a temperature of 200°C to 1000°C. (However, R indicates the average composition of organic groups having carbon atoms directly bonded to silicon atoms, and n is 0 to 1.
Each represents a range of numbers. ) A method for producing porous spherical silica particles represented by 2. The method for producing porous spherical silica fine particles according to claim 1, wherein the temperature during heating in the presence of an alcohol having a boiling point of 120°C or higher at normal pressure is 50°C or higher. 3 A hydrolyzable silicon compound has the general formula ()R'mSiX4-m (where R' is an alkyl group, an aryl group, or an unsaturated aliphatic residue having up to 10 carbon atoms, which may have a substituent). (X represents at least one group selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, and an acyloxy group, and m represents an integer in the range of 0 to 3.) Claim 1 or 2 is at least one selected from the group consisting of silane compounds and derivatives thereof represented by (however, exclusive use of silane compounds and derivatives thereof represented by m = 2 or 3 in general formula ()) A method for producing porous spherical silica fine particles as described in . 4 Claims 1 and 2 wherein the alcohol with a boiling point of 120°C or higher at normal pressure is a polyhydric alcohol of dihydric or higher hydricity.
or 3. The method for producing porous spherical silica particles according to 3.