JP4925706B2 - Method for producing silica-based composite oxide particles - Google Patents

Description

  The present invention relates to a method for producing spherical monolithic composite oxide particles having high monodispersity comprising silica and a metal oxide other than silica. More specifically, the present invention relates to monodisperse, high-circularity silica-based composite oxide particles that have been difficult to produce conventionally.

  Conventionally, a metal alkoxide such as tetraethoxysilane or tetramethoxysilane is used as a raw material, and the metal alkoxide is hydrolyzed and polycondensed in an organic solvent containing water in the presence of a catalyst to form a highly monodispersed spherical shape. Methods for producing silica particles are known. A method of producing metal oxide particles using a polycondensation reaction using an organometallic compound such as a metal alkoxide as a raw material is generally called a sol-gel method. By using the metal alkoxide in combination, so-called silica-based composite oxide particles such as silica-titania, silica-alumina, and silica-zirconia can be produced.

  Silica-based composite oxide particles produced by the sol-gel method can exhibit various characteristic performances that cannot be obtained with silica alone by combining various metal oxides with silica as the main component. Therefore, it is applied to various uses. For example, by changing the compounding ratio of silica and a metal oxide other than silica, the refractive index of the particles can be arbitrarily adjusted without impairing optical transparency. By using particles having a refractive index that matches that of the resin as a filler, it is possible to obtain an excellent transparent composite resin having improved performance such as mechanical strength and low thermal expansion while maintaining transparency.

  By the way, in the conventional method, when the content of the metal oxide other than silica exceeds 20 mol%, the aggregation of particles and generation of new fine particles are likely to occur, and a spherical silica-based composite having good monodispersibility. There was a problem that it was difficult to obtain oxide particles. In general, when obtaining spherical inorganic oxide particles, the content of metal oxides other than silica is preferably 30 mol% or less, more preferably 20 mol% or less, particularly metal oxides other than silica. It is known that when the content of the product is selected in the range of 0.01 to 15 mol%, it becomes close to a true sphere having a uniform particle diameter (see Patent Document 1).

  A method for producing spherical silica particles having a metal oxide content other than silica of 30 to 50 mol% and a particle diameter variation coefficient of 30% or less is also known. The properties of the particles are such that the particle diameter is 0.11 to 0.45 μm and the coefficient of variation is 8 to 19%, and particles having excellent monodispersity with a coefficient of variation of 7% or less cannot be synthesized (Patent Document 2). reference).

Japanese Patent Publication No.3-333721 JP 2003-252616 A

  Therefore, an object of the present invention is to provide a method for efficiently producing monodisperse, high-circularity silica-based composite oxide particles.

  This inventor repeated earnest research in order to solve the said subject. As a result, when the reaction is performed while controlling the composition of the reaction solution so that the concentration of acetonitrile always exceeds a specific value, even if the content of metal oxides other than silica is high, it is monodisperse, circular The present inventors have found that silica-based composite oxide particles having a high degree can be synthesized and have completed the present invention.

  That is, the present invention relates to “a silicon alkoxide and / or a condensable compound derived from the alkoxide” (also referred to as “silica raw material”), and “silicone” in a reaction solvent comprising water and an organic solvent. And at least one selected from the group consisting of a metal alkoxide other than the above, a condensable compound derived from the alkoxide, and a salt of a metal other than silicon (hereinafter also referred to as “foreign oxide source material”). In the method for producing silica-based composite oxide particles including the step of reacting with each other, acetonitrile is used as at least one component of the organic solvent, and the reaction is performed while maintaining the concentration of acetonitrile contained in the reaction liquid at 20% by mass or more. It is a method characterized by performing.

  In another aspect of the present invention, (1) a step of mixing a silica raw material and a heterogeneous oxide raw material, and (2) a reaction solvent comprising water and an organic solvent, the mixture obtained in the step. In the method for producing silica-based composite oxide particles including the step of adding and reacting with acetonitrile, acetonitrile is used as at least one component of the organic solvent, and the concentration of acetonitrile contained in the reaction solution is kept at 20% by mass or more. In this method, the reaction is performed.

  The reaction liquid here means a reaction solvent at the start of the reaction (also a dispersion medium if particles are produced), a catalyst, a solid component (silica-based composite oxide particles) produced by the reaction, a reaction. Means a mixture containing all components such as by-products such as alcohol, unreacted raw materials added to the reaction system, and water and organic solvents added during the reaction, if necessary. The concentration is based on the total mass of this mixture.

  According to the method of the present invention, silica-based composite oxide particles having high monodispersity and high circularity, which have been difficult to produce conventionally, can be obtained efficiently. In particular, when the method of the present invention is adopted for the production of silica-based composite oxide particles containing titania or zirconia as a metal oxide other than silica, the monodispersity is higher than when the conventional method is adopted. True spherical particles are obtained.

  The composite oxide particles of silica and titania or zirconia obtained by the method of the present invention are high refractive index particles having high optical transparency, and the addition of an antireflection layer, a transparent high refractive index resin or a film. It is extremely useful as an agent.

  Such an effect of the present invention is more prominent as the content of metal oxides other than silica is higher. In the method of the present invention, the content of metal oxides other than silica is 20 mol% or more, particularly 30 mol% or more. This is superior to conventional methods in that it can efficiently produce particles having a particle diameter variation coefficient of 7% or less and a circularity of particles of 0.8 or more. It can be said that

  In the production method of the present invention, as in the conventional sol-gel method, a silica raw material and a different oxide raw material are added to a reaction solvent containing water and an organic solvent, and these raw materials are reacted. Although a process is included, in the production method of the present invention, the reaction in this process must always be performed in the presence of acetonitrile at a predetermined concentration. That is, in the production method of the present invention, it is necessary to use acetonitrile as at least one component of the organic solvent and perform the reaction while maintaining the concentration of acetonitrile in the liquid component contained in the reaction solution at 20% by mass or more. . By satisfying such conditions, it is possible to efficiently obtain silica-based composite oxide particles having high monodispersibility and high circularity.

  When synthesizing silica-based composite oxide particles by the sol-gel method, if the content of metal oxides other than silica increases, the surface potential of the particles decreases and sufficient repulsive force cannot be obtained and the particles tend to aggregate. It becomes difficult to obtain particles having high monodispersity and roundness. Such a decrease in surface potential can be suppressed to some extent by carrying out the reaction in a solvent (or dispersion medium) containing a high concentration of an aprotic polar solvent. When an experiment was carried out using a protic polar solvent, the desired effect could not be obtained when an aprotic polar solvent other than acetonitrile was used. At present, the mechanism is unknown, but it is possible to obtain silica-based composite oxide particles that are specifically monodisperse and highly circular due to some specific action when acetonitrile is used. Seem.

  Such an effect can be obtained by keeping the concentration of acetonitrile in the liquid component contained in the reaction solution at 20% by mass or more, but it is preferable to keep it at 20% by mass or more from the viewpoint of high effect. . Further, it is preferable to increase the concentration of acetonitrile at the initial stage of the reaction, and the concentration of acetonitrile at the start of the reaction is preferably 70% by mass or more, particularly preferably 80% by mass or more.

  During the reaction, the concentration of acetonitrile in the reaction solution decreases from the concentration in the reaction solvent at the start of the reaction due to the supply of raw material (silica raw material and different oxide raw material) and ammonia water supplied as necessary. I will do it. For this reason, in order to keep the concentration of acetonitrile in the liquid component contained in the reaction liquid at 20% by mass or more, a sufficient amount of acetonitrile is included as a reaction solvent used at the start of the reaction in consideration of these mass increases in advance. What is necessary is just to use a thing or to supply acetonitrile intermittently or continuously during reaction so that the density | concentration of acetonitrile may maintain a predetermined range.

  In the production method of the present invention, the silica raw material and the heterogeneous oxide raw material are reacted in a solvent containing acetonitrile, and the concentration of acetonitrile is always kept at a predetermined value or higher throughout the reaction. There is no particular difference from the case where the silica-based composite oxide particles are produced by the conventional sol-gel method, and any reaction reagent used in the conventional method can be used without any particular limitation.

That is, as a silica raw material, a silicon alkoxide represented by the general formula Si (OR) ₄ or SiR′n (OR) _4-n (wherein R and R ′ may include an ether bond or an ester bond). An organic group, n is an integer of 1 to 3), and a low-condensate obtained by partially hydrolyzing these silicon alkoxides (the low-condensate has an alkoxy group or a hydroxyl group in the molecule). Or a mixture thereof can be preferably used. In the general formula of the silicon alkoxide, a plurality of R contained in one molecule may be different from each other, but since the raw materials are easily available, a plurality of R contained in one molecule is usually The same compounds are preferably used. R and R ′ can be used without any limitation as long as they are organic groups. However, when they are alkyl groups, they can be suitably used because of easy availability of raw materials, particularly methyl groups, ethyl groups, isopropyl groups, butyl groups, etc. A lower alkyl group is preferred because it has good compatibility with organic solvents and has a low boiling point of alcohol produced as a result of hydrolysis and can be easily removed from the particles.

Further, as the heterogeneous oxide raw material, alkoxides of metals of Group 1, Group 2, Group 3, Group 4, Group 13, and Group 14 of the periodic table are not particularly limited and used. Examples of metal alcosides that can be suitably used include general formulas M ₁ (OR), M ₂ (OR) ₂ , M ₃ (OR) ₃ , M ₄ (OR) ₄ , M ₁₃ (OR) ₃ , M ₁₄ (OR). ₄ (wherein R is an alkyl group, particularly preferably one having 4 or less carbon atoms). Here, M ₁ is a Group 1 metal, M ₂ is a Group 2 metal, M ₃ is a Group 3 metal, M ₄ is a Group 4 metal, M ₁₃ is a Group 13 metal, M ₁₄ Is a Group 14 metal, and examples of suitable metals include lithium, sodium, potassium, magnesium, calcium, strontium, barium, scandium, yttrium, titanium, boron, zirconium, hafnium, aluminum, germanium, tin or lead. Can be mentioned.

  Specific examples of the above-mentioned compounds that are preferably used in the present invention include organic sodium compounds such as sodium methoxide, sodium ethoxide, sodium propoxide, etc .; in these compounds, the sodium atom is substituted with lithium, potassium, etc. Group 1 compounds; organic magnesium compounds such as magnesium methoxide, magnesium ethoxide, magnesium propoxide; group 2 compounds in which magnesium is replaced with calcium, strontium, barium, etc .; titanium tetraisopropoxide, titanium tetrabutoxide, etc. Ti compounds of these groups; Group 4 or Group 14 compounds in which the titanium atoms in these compounds are replaced by zirconium, hafnium, germanium, tin, lead, etc .; aluminum ethoxide, aluminum ions Propoxide, Al compounds such as aluminum butoxide; Group 13 compound was replaced aluminum atoms with boron or the like in these compounds; and the like. In addition to the metal alkoxide, compounds such as the above-mentioned metal acetates, carboxylates such as acetoacetate, calcium chloride, and calcium salicylate monohydrate can also be used. Further, a condensable compound derived from a metal alkoxide can be used as in the case of the silica raw material.

  In order to obtain spherical silica-based composite oxide particles having particularly high monodispersity, it is preferable to use an alkoxide of a metal of Group 4 of the periodic table among the above compounds. Of these, it is most preferable to use an alkoxide of titanium and / or zirconium.

  In the production method of the present invention, the silica raw material and the different oxide raw material are added and reacted in a reaction solvent containing water and an organic solvent. The reaction solvent contains 20% by mass or more of acetonitrile. There is a need. It is preferable to add a catalyst for promoting the reaction, specifically the hydrolysis reaction and the condensation polymerization reaction, to the reaction solvent.

  The catalyst used in the present invention is not particularly limited as long as it has a function of promoting the hydrolysis and polycondensation reaction of metal alkoxide. Usually, an acid or a base can be used, but it is preferable to use a base catalyst because spherical and highly monodisperse particles can be obtained. Examples of the base catalyst that can be suitably used in the present invention include inorganic bases such as ammonia, lithium hydroxide, sodium hydroxide, and potassium hydroxide; methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, Propylamine, tripropylamine, pyridine, imidazole, piperidine, quinoline, pyrrole, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] unde-7-cene, water And organic bases such as tetramethylammonium oxide. Among these, in the case of a base that does not contain a metal such as ammonia or amine, such a catalyst is used because the base component and the metal component do not remain in the particle by firing the produced silica-based oxide particles. It is particularly preferred to do this.

  Although the amount of the catalyst added varies depending on the type of catalyst used, the type of water and organic solvent in the reaction solution, and the blending ratio, it cannot be generally stated, but the pH of the reaction solvent is 10 or more, preferably 11 or more. It is preferable to add to. Note that if the reaction is carried out while adding the raw materials, the amount of the reaction solution increases and the concentration of the catalyst changes, so the catalyst is supplied continuously or intermittently so that the pH of the reaction solution remains within the above range during the reaction. It is preferable. In the case of ammonia which is most suitable as a catalyst, it is suitable that the amount is 2 to 15% by mass, preferably 3 to 7% by mass, based on the mass of the reaction solution from the start to the end of the reaction. Specifically, the mass of the reaction liquid referred to here is the mass of the entire reaction liquid including the organic solvent containing water initially charged, the supplied raw material, the supplied catalyst, and the like.

  The reaction solvent is not particularly limited as long as it contains water and 20% by mass or more of acetonitrile, but the concentration of acetonitrile (initial concentration) is 70% by mass or more, particularly 80% by mass or more from the viewpoint of effect. preferable. Moreover, although water concentration is not specifically limited, It is preferable that all the components except acetonitrile and a catalyst are water. Although not particularly necessary, a water-soluble organic solvent such as alcohol can be added to the reaction solvent.

  A method of adding a raw material to such an organic solvent and reacting it can be carried out in the same manner as the conventional sol-gel method. However, in order to produce silica-based composite oxide particles having good properties, silica It is preferable that the raw material and the different oxide raw material are mixed in advance and then added to the reaction solvent. When silicon alkoxide is used as the silica raw material, it is more homogeneous that part or all of the silicon alkoxide is partially hydrolyzed (hereinafter also referred to as partial hydrolysis) prior to mixing. This is preferable because a simple particle can be obtained. When partially hydrolyzing, it is preferable to use together an organic solvent such as alcohol having compatibility with both the alkoxide and water. Moreover, it is preferable to add a catalyst when performing partial hydrolysis because the partial hydrolysis reaction proceeds rapidly. An acid is suitable as the catalyst, and specific examples include hydrochloric acid, sulfuric acid, nitric acid, oxalic acid and the like, but there is no particular limitation. It is preferable to use an acid having a pH in the range of 1 to 4.

  The mixing of the silica raw material and the different oxide raw material is suitably performed by appropriately mixing and stirring a predetermined amount of the raw material according to the composition of the silica-based composite oxide to be obtained. As a result, a composite alkoxide in which both raw materials are combined is formed, so that even if the content of the metal oxide other than silica is 30 mol% or more, the variation coefficient of the particle diameter is 7% or less and True spherical silica-based composite oxide particles can be obtained efficiently. In the case where the silicon alkoxide is partially hydrolyzed, the reaction solution at that time may be mixed with the different oxide raw material.

  In the method of the present invention, it is of course possible to carry out the reaction by separately adding each raw material to the reaction solvent.

  When adding silica raw materials and different oxide raw materials, or composite alkoxides prepared by premixing to the reaction solvent, these raw materials may be diluted with an organic solvent such as alcohol or acetonitrile. However, in order to increase the slurry concentration in the reaction solution, it is desirable to use the solution without diluting it at all, or even when diluting, the dilution rate is preferably limited to about 50% by mass.

  When these raw materials are added to the reaction solvent, it is preferable to add them dropwise in the liquid from the viewpoint that aggregated particles are not easily formed. Dropping in the liquid means that the tip of the source material supply pipe (source material discharge port) is immersed in the reaction solution. The position of the tip of the discharge port is not particularly limited as long as it is in the liquid, but a position where stirring is sufficiently performed such as in the vicinity of the stirring blade is desirable.

  In addition, when a basic catalyst such as ammonia is used as the catalyst, an alkaline aqueous solution prepared separately together with the raw material may be dropped simultaneously into the reaction solution. As this alkaline aqueous solution, 10-30 mass% ammonia water is suitable. In the supply, the number of moles of water in the alkaline aqueous solution to be fed is 1 to 6 times, preferably 2 to the total number of moles of silicon and metals other than silicon contained in the raw material supplied simultaneously. It is preferable to add the alkaline aqueous solution dropwise at a supply amount that is 5 times. Although it is not necessary to drop the alkaline aqueous solution in the liquid, it is preferable that the alkaline aqueous solution is dropped in the liquid near the stirring blade because stirring in the reaction liquid is sufficiently performed. By simultaneously dropping the alkaline aqueous solution as described above, particles can be synthesized with a high solid content concentration, so that synthesis with high yield (productivity) is possible.

  Further, in order to increase the monodispersity, it is preferable that the dropping rate is lowered. However, if the dropping speed is too slow, it takes a long time to complete the synthesis. Therefore, it is preferable to slow the dropping speed at the initial stage of synthesis and increase the dropping speed after the latter half.

  It is preferable that the raw material and the alkaline aqueous solution are continuously dropped from the start to the end of the dropping. The term “continuous” as used herein means that an interval of preferably 10 minutes or longer, more preferably 3 minutes or longer is not provided. The dropping speed is not necessarily constant, but it is desirable to change continuously when changing the dropping speed. In the case of intermittent supply at intervals, the atmosphere in the reaction solution may be disturbed by the rapid addition of water, causing aggregation of particles and generation of new core particles.

  The temperature of the reaction solution for carrying out the reaction may be appropriately determined according to the type of raw material used, but is usually in the range of 0 to 50 ° C. The reaction proceeds promptly after the raw material is supplied, and a Si—O—Si bond or a Si—OM bond (M is a metal atom other than silicon) by a condensation polymerization reaction (usually dealcoholization condensation) that occurs following hydrolysis. Meaning) and as a result, silica-based composite oxide particles are formed.

  In the production method of the present invention, the produced silica-based composite oxide particles are obtained as a colloidal particle dispersion dispersed in the reaction solution. Depending on the application, it may be used as it is, but it may be solid-liquid separated by a method such as centrifugation, filtration, distillation under reduced pressure, or spray drying, and taken out in the form of powder. It may be used after substitution with a solvent. There is no particular limitation on the method for replacing the solvent, and after removing the powder in the form of powder, the desired solvent may be added and redispersed, or the operation of concentration by ultrafiltration and the addition of the desired solvent are repeated. May be replaced.

  Moreover, after synthesizing the particles, the taken-out powder can be dried. The drying temperature for drying is preferably in the range of 50 to 300 ° C., and the drying time is preferably between several hours to several days. The dried powder can be fired at higher temperatures. The firing temperature is preferably in the range of 300 to 1300 ° C, and the firing time is preferably in the range of 1 to 24 hours. The particles after drying or firing can be pulverized using a ball mill, a jet mill or the like. Moreover, when using it disperse | distributing to resin etc., particle | grains can be disintegrated simultaneously with dispersion | distribution to resin by using a high shearing disperser.

  According to the production method of the present invention, for example, even when the content ratio of the metal oxide other than silica is as high as 20 mol% or 30 mol%, the particle diameter variation coefficient is 7% or less, preferably Silica-based composite oxide particles exhibiting excellent monodispersity of 6% or less can be efficiently produced. Further, according to the production method of the present invention, silica-based composite oxide particles having a shape close to a true sphere having a particle circularity of 0.8 or more, preferably 0.9 or more, can also be produced efficiently.

  The shape of the silica-based composite oxide particles can be confirmed by using a scanning type or transmission type electron microscope. The average particle size and monodispersity (coefficient of variation of particle size) of the particles can be determined by analyzing the electron microscope image or measuring with a highly accurate particle size distribution meter.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

  Various physical properties of the silica-based composite oxide particles were measured as follows.

(1) "Average particle diameter", "Particle diameter variation coefficient", and "Circularity"
These physical properties were determined by analyzing 200 or more particles using an image analyzer using a scanning electron microscope image. Here, “circularity” is a parameter representing how close a particle is to a sphere, and a value represented by (4π × S) / L ² where S is the projected area of the particle and L is the circumference. It is.

(2) Refractive index The refractive index of the particles was measured by a liquid immersion method. That is, a solvent having a different refractive index (for example, toluene, 1-bromonaphthalene, 1-chloronaphthalene, diiodomethane, sulfur-containing diiodomethane, etc.) is appropriately mixed to form a mixed solvent having an arbitrary refractive index, and particles therein And the refractive index of the most transparent particle dispersion at 25 ° C. was defined as the refractive index of the particles. The refractive index of the solvent was measured at 25 ° C. using an Abbe refractometer.

(3) Crystal form The crystal form of the particles was identified using an X-ray diffractometer.

Example 1
(Preparation of complex alkoxide solution)
In a 2 liter screw-mouth bottle, 548 g of tetramethoxysilane (Tama Chemical Co., Ltd.) and 110 g of methanol were charged and stirred. 0.04 mass% dilute hydrochloric acid 29g was added to this, and the partial hydrolysis of tetramethoxysilane was performed for 15 minutes. The amount of water used for partial hydrolysis of tetramethoxysilane was 4.0 equivalents with respect to titanium tetraisopropoxide added later. Subsequently, titanium tetraisopropoxide (Nihon Soda Co., Ltd., trade name: A-1) 114 g (titanium tetraisopropoxide with respect to the total number of moles of tetramethoxysilane and titanium tetraisopropoxide was added to the obtained reaction solution. Was mixed with 23 g of isopropyl alcohol to obtain a colorless and transparent composite alkoxide solution.

(Manufacture of silica-based composite oxide particles)
A jacketed glass reactor with an internal volume of 5 liters equipped with a stirring blade was charged with 667 g and 133 g of acetonitrile and ammonia water (25% by mass), respectively, and the temperature of the circulating water in the jacket was set to 40 ° C. and stirred at 100 rpm. did. Next, 823 g of the composite alkoxide solution prepared in advance was supplied to the reaction solvent thus prepared over 5 hours. A 1/8 inch SUS tube was used for the supply. The proportion of acetonitrile at this time was 83% by mass at the start of the reaction and 37% by mass at the end of the reaction.

  After completion of the reaction, a slurry of silica-based composite oxide particles was taken out. As a result of observing the obtained particles with a scanning electron microscope, the particle shape was spherical. As a result of image analysis, the average particle size was 0.24 μm, the coefficient of variation of the particle size was 4.9%, and the circularity of the particles was 0.93. Thereafter, the obtained slurry was coagulated and settled, and a part of the filtered and dried particles was fired at 900 ° C. for 10 hours. As a result of observing the fired particles with a scanning electron microscope, the average particle size was reduced by about 7%, but other numerical values were almost the same as described above. Further, the refractive index of the particles was 1.52. As a result of X-ray diffraction, the dried particles and the fired particles were both amorphous.

Example 2
(Preparation of complex alkoxide solution)
In a 2 liter screw mouth bottle, 487 g of tetramethoxysilane (Tama Chemical Co., Ltd.) and 97 g of methanol were charged and stirred. To this, 58 g of 0.04 mass% dilute hydrochloric acid was added, and tetramethoxysilane was partially hydrolyzed for 15 minutes. The amount of water used for partial hydrolysis of tetramethoxysilane was 4.0 equivalents with respect to titanium tetraisopropoxide added later. Subsequently, 227 g of titanium tetraisopropoxide (Nippon Soda Co., Ltd., trade name: A-1) (the blending ratio of titanium tetraisopropoxide with respect to the total number of moles of tetramethoxysilane and titanium tetraisopropoxide is 20 Mol%) was diluted with 46 g of isopropyl alcohol to obtain a colorless and transparent composite alkoxide solution.

(Manufacture of silica-based composite oxide particles)
A jacketed glass reactor with an internal volume of 5 liters equipped with a stirring blade was charged with 667 g and 133 g of acetonitrile and ammonia water (25% by mass), respectively, and the temperature of the circulating water in the jacket was set to 40 ° C. and stirred at 100 rpm. did. Next, 915 g of the composite alkoxide solution prepared in advance was supplied to the reaction solvent thus prepared over 5 hours. A 1/8 inch SUS tube was used for the supply. The proportion of acetonitrile at this time was 83% by mass at the start of the reaction and 35% by mass at the end of the reaction.

  After completion of the reaction, a slurry of silica-based composite oxide particles was taken out. As a result of observing the obtained particles with a scanning electron microscope, the particle shape was spherical. As a result of image analysis, the average particle size was 0.18 μm, the variation coefficient of the particle size was 5.2%, and the circularity of the particles was 0.91. Thereafter, the obtained slurry was coagulated and settled, and a part of the filtered and dried particles was fired at 900 ° C. for 10 hours. As a result of observing the fired particles with a scanning electron microscope, the average particle size was reduced by about 7%, but other numerical values were almost the same as described above. The refractive index of the particles was 1.60. As a result of X-ray diffraction, the dried particles were amorphous, and the particles fired at 900 ° C. detected a peak derived from anatase titania at around 25.2 °. Therefore, it was found that the fired particles were spherical particles in which titania microcrystals were dispersed in a silica matrix.

Example 3
(Preparation of complex alkoxide solution)
Tetramethoxysilane (Tama Chemical Co., Ltd.) (408 g) and methanol (82 g) were charged into a 2 liter screw mouth bottle and stirred. To this, 48 g of 0.04 mass% diluted hydrochloric acid was added, and tetramethoxysilane was partially hydrolyzed for 15 minutes. The amount of water used for partial hydrolysis of tetramethoxysilane was 2.0 equivalents with respect to titanium tetraisopropoxide added later. Subsequently, 375 g of titanium tetraisopropoxide (Nippon Soda Co., Ltd., trade name: A-1) (the compounding ratio of titanium tetraisopropoxide to the total number of moles of tetramethoxysilane and titanium tetraisopropoxide is 33 Mol) was diluted with 75 g of isopropyl alcohol to obtain a colorless and transparent complex alkoxide solution.

(Manufacture of silica-based composite oxide particles)
A jacketed glass reactor with an internal volume of 5 liters equipped with a stirring blade was charged with 667 g and 133 g of acetonitrile and ammonia water (25% by mass), respectively, and the temperature of the circulating water in the jacket was set to 40 ° C. and stirred at 100 rpm. did. Next, 988 g of the composite alkoxide solution prepared in advance was supplied to the reaction solvent thus prepared over 5 hours. A 1/8 inch SUS tube was used for the supply. The proportion of acetonitrile at this time was 83% by mass at the start of the reaction and 34% by mass at the end of the reaction.

  After completion of the reaction, a slurry of silica-based composite oxide particles was taken out. As a result of observing the obtained particles with a scanning electron microscope, the particle shape was spherical. As a result of image analysis, the average particle size was 0.12 μm, the variation coefficient of the particle size was 5.8%, and the circularity of the particles was 0.87. Thereafter, the obtained slurry was coagulated and settled, and a part of the filtered and dried particles was fired at 900 ° C. for 10 hours. As a result of observing the fired particles with a scanning electron microscope, the average particle size was reduced by about 7%, but other numerical values were almost the same as described above. Further, the refractive index of the particles was 1.70. As a result of X-ray diffraction, the dried particles were amorphous, and the particles fired at 900 ° C. detected a peak derived from anatase titania at around 25.2 °. Therefore, it was found that the fired particles were spherical particles in which titania microcrystals were dispersed in a silica matrix.

Example 4
(Preparation of complex alkoxide solution)
In a 5-liter screw mouth bottle, 365 g of tetramethoxysilane (Tama Chemical Co., Ltd.) and 73 g of methanol were charged and stirred. To this, 43 g of 0.04 mass% dilute hydrochloric acid was added, and tetramethoxysilane was partially hydrolyzed for 15 minutes. The amount of water used for partial hydrolysis of tetramethoxysilane was 1.5 equivalents with respect to titanium tetraisopropoxide added later. Subsequently, 455 g of titanium tetraisopropoxide (Nippon Soda Co., Ltd., trade name: A-1) (the compounding ratio of titanium tetraisopropoxide with respect to the total number of moles of tetramethoxysilane and titanium tetraisopropoxide is 40 Mol%) was diluted with 91 g of isopropyl alcohol to obtain a colorless and transparent composite alkoxide solution.

(Manufacture of silica-based composite oxide particles)
A jacketed glass reactor with an internal volume of 5 liters equipped with a stirring blade was charged with 667 g and 133 g of acetonitrile and ammonia water (25% by mass), respectively, and the temperature of the circulating water in the jacket was set to 40 ° C. and stirred at 100 rpm. did. Next, 1027 g of the composite alkoxide solution prepared in advance was supplied to the reaction solvent thus prepared over 5 hours. A 1/8 inch SUS tube was used for the supply. The proportion of acetonitrile at this time was 83% by mass at the start of the reaction and 33% by mass at the end of the reaction.

  After completion of the reaction, a slurry of silica-based composite oxide particles was taken out. As a result of observing the obtained particles with a scanning electron microscope, the particle shape was spherical. As a result of image analysis, the average particle size was 0.11 μm, the variation coefficient of the particle size was 6.1%, and the circularity of the particles was 0.85. Thereafter, the obtained slurry was coagulated and settled, and a part of the filtered and dried particles was fired at 900 ° C. for 10 hours. As a result of observing the fired particles with a scanning electron microscope, the average particle size was reduced by about 7%, but other numerical values were almost the same as described above. The refractive index of the particles was 1.76. As a result of X-ray diffraction, the dried particles were amorphous, and the particles fired at 900 ° C. detected a peak derived from anatase titania at around 25.2 °. Therefore, it was found that the fired particles were spherical particles in which titania microcrystals were dispersed in a silica matrix.

Example 5
(Preparation of complex alkoxide solution)
Tetramethoxysilane (Tama Chemical Co., Ltd.) (408 g), methanol (41 g), and acetonitrile (41 g) were charged into a 2 liter screw mouth bottle and stirred. To this, 48 g of 0.04 mass% diluted hydrochloric acid was added, and tetramethoxysilane was partially hydrolyzed for 15 minutes. The amount of water used for partial hydrolysis of tetramethoxysilane was 2.0 equivalents with respect to titanium tetraisopropoxide added later. Subsequently, 375 g of titanium tetraisopropoxide (Nippon Soda Co., Ltd., trade name: A-1) (the compounding ratio of titanium tetraisopropoxide to the total number of moles of tetramethoxysilane and titanium tetraisopropoxide is 33 Mol%) with 75 g of acetonitrile was added to obtain a colorless and transparent complex alkoxide solution.

(Manufacture of silica-based composite oxide particles)
A jacketed glass reactor with an internal volume of 5 liters equipped with a stirring blade was charged with 667 g and 133 g of acetonitrile and ammonia water (25% by mass), respectively, and the temperature of the circulating water in the jacket was set to 40 ° C. and stirred at 100 rpm. did. Next, 988 g of the composite alkoxide solution prepared in advance was supplied to the reaction solvent thus prepared over 5 hours. A 1/8 inch SUS tube was used for the supply. The proportion of acetonitrile at this time was 83% by mass at the start of the reaction and 40% by mass at the end of the reaction.

  After completion of the reaction, a slurry of silica-based composite oxide particles was taken out. As a result of observing the obtained particles with a scanning electron microscope, the particle shape was spherical. As a result of image analysis, the average particle size was 0.11 μm, the variation coefficient of the particle size was 5.3%, and the circularity of the particles was 0.90. Thereafter, the slurry was coagulated and settled, and some of the filtered and dried particles were fired at 900 ° C. for 10 hours. As a result of observing the fired particles with a scanning electron microscope, the average particle size was reduced by about 7%, but other numerical values were almost the same as described above. Further, the refractive index of the particles was 1.70. As a result of X-ray diffraction, the dried particles were amorphous, and the particles fired at 900 ° C. detected a peak derived from anatase titania at around 25.2 °. Therefore, it was found that the fired particles were spherical particles in which titania microcrystals were dispersed in a silica matrix.

Example 6
(Preparation of complex alkoxide solution)
In a 2 liter screw mouth bottle, 408 g of tetramethoxysilane (Tama Chemical Co., Ltd.) and 204 g of methanol were charged and stirred. To this, 48 g of 0.04 mass% diluted hydrochloric acid was added, and tetramethoxysilane was partially hydrolyzed for 15 minutes. The amount of water used for partial hydrolysis of tetramethoxysilane was 2.0 equivalents with respect to titanium tetraisopropoxide added later. Subsequently, 375 g of titanium tetraisopropoxide (Nippon Soda Co., Ltd., trade name: A-1) is added to 750 g of acetonitrile (ratio of titanium tetraisopropoxide to the total number of moles of tetramethoxysilane and titanium tetraisopropoxide). Was added at 33 mol%) to obtain a colorless and transparent composite alkoxide solution.

(Manufacture of silica-based composite oxide particles)
A jacketed glass reactor with an internal volume of 5 liters equipped with a stirring blade was charged with 667 g and 133 g of acetonitrile and ammonia water (25% by mass), respectively, and the temperature of the circulating water in the jacket was set to 40 ° C. and stirred at 100 rpm. did. Next, 1786 g of the composite alkoxide solution prepared in advance was supplied to the reaction solvent thus prepared over 5 hours. A 1/8 inch SUS tube was used for the supply. The proportion of acetonitrile at this time was 83% by mass at the start of the reaction and 23% by mass at the end of the reaction.

  After completion of the reaction, a slurry of silica-based composite oxide particles was taken out. As a result of observing the obtained particles with a scanning electron microscope, the particle shape was spherical. As a result of image analysis, the average particle size was 0.12 μm, the variation coefficient of the particle size was 6.7%, and the circularity of the particles was 0.82. Thereafter, the slurry was coagulated and settled, and some of the filtered and dried particles were fired at 900 ° C. for 10 hours. As a result of observing the fired particles with a scanning electron microscope, the average particle size was reduced by about 7%, but other numerical values were almost the same as described above. Further, the refractive index of the particles was 1.70. As a result of X-ray diffraction, the dried particles were amorphous, and the particles fired at 900 ° C. detected a peak derived from anatase titania at around 25.2 °. Therefore, it was found that the fired particles were spherical particles in which titania microcrystals were dispersed in a silica matrix.

Example 7
(Preparation of complex alkoxide solution)
In a 2-liter screw mouth bottle, 518 g of tetramethoxysilane (Tama Chemical Co., Ltd.) and 104 g of methanol were charged and stirred. To this, 43 g of 0.04 mass% dilute hydrochloric acid was added, and tetramethoxysilane was partially hydrolyzed for 15 minutes. The amount of water used for partial hydrolysis of tetramethoxysilane was 4.0 equivalents with respect to zirconium tetrabutoxide added later. Subsequently, a solution obtained by diluting 230 g of zirconium tetrabutoxide (the compounding ratio of zirconium tetrabutoxide with respect to the total number of moles of tetramethoxysilane and zirconium tetrabutoxide is 15 mol%) with 46 g of n-butanol was added, and a colorless transparent composite alkoxide was added. A solution was obtained.

(Manufacture of silica-based composite oxide particles)
A jacketed glass reactor with an internal volume of 5 liters equipped with a stirring blade was charged with 667 g and 133 g of acetonitrile and ammonia water (25% by mass), respectively, and the temperature of the circulating water in the jacket was set to 40 ° C. and stirred at 100 rpm. did. Next, 941 g of the composite alkoxide solution prepared in advance was supplied to the reaction solvent thus prepared over 5 hours. A 1/8 inch SUS tube was used for the supply. The proportion of acetonitrile at this time was 83% by mass at the start of the reaction and 35% by mass at the end of the reaction.

  After completion of the reaction, a slurry of silica-based composite oxide particles was taken out. As a result of observing the obtained particles with a scanning electron microscope, the particle shape was spherical. As a result of image analysis, the average particle size was 0.24 μm, the variation coefficient of the particle size was 6.4%, and the circularity of the particles was 0.88. Thereafter, the slurry was coagulated and settled, and some of the filtered and dried particles were fired at 900 ° C. for 10 hours. As a result of observing the fired particles with a scanning electron microscope, the average particle size was reduced by about 7%, but other numerical values were almost the same as described above. The refractive index of the particles was 1.54. As a result of X-ray diffraction, the dried particles and the fired particles were both amorphous.

Comparative Example 1
Silica-based composite oxide particles were synthesized in the same manner as in Example 2 except that isopropyl alcohol was used instead of acetonitrile. At this time, the proportion of acetonitrile was 0% by mass from the start of the reaction to the end of the reaction. After completion of the reaction, the slurry of the silica-based composite oxide particles was taken out, and the obtained particles were observed with a scanning electron microscope. As a result, the particle shape was spherical but somewhat distorted. As a result of image analysis, the average particle size was 0.47 μm, the variation coefficient of the particle size was 15.2%, and the circularity of the particles was 0.71, and particles with high monodispersity and high circularity were not obtained.

Comparative Example 2
Silica-based composite oxide particles were synthesized in the same manner as in Example 3 except that isopropyl alcohol was used instead of acetonitrile. At this time, the proportion of acetonitrile was 0% by mass from the start of the reaction to the end of the reaction. After completion of the reaction, the slurry of the silica-based composite oxide particles was taken out, and the obtained particles were observed with a scanning electron microscope. As a result, the particle shape was spherical but somewhat distorted. As a result of image analysis, the average particle size was 0.95 μm, the variation coefficient of the particle size was 21.3%, the circularity of the particles was 0.67, and particles with high monodispersity and high circularity were not obtained.

Comparative Example 3
Silica-based composite oxide particles were synthesized in the same manner as in Example 3 except that methanol was used instead of acetonitrile. At this time, the proportion of acetonitrile was 0% by mass from the start of the reaction to the end of the reaction. After completion of the reaction, a slurry of silica-based composite oxide particles was taken out, but most of the particles were precipitated. As a result of observing the obtained particles with a scanning electron microscope, it was not a particle shape but an aggregated mass of several μm, and particles having high monodispersity and high circularity were not obtained.

  The reaction conditions of Examples 1 to 7 and Comparative Examples 1 to 3 and the obtained particle properties are summarized in Tables 1 and 2.

Comparative Examples 4-10
Silica-based composite oxide particles were synthesized in the same manner as in Example 3 except that the solvent shown in Table 3 was used instead of acetonitrile. At this time, the proportion of acetonitrile was 0% by mass from the start of the reaction to the end of the reaction. After completion of the reaction, a slurry of silica-based composite oxide particles was taken out, but most of the particles were precipitated or gelled. As a result of observing the obtained particles with a scanning electron microscope, it was not a particle shape but an aggregated mass of several μm, and particles having high monodispersity and high circularity were not obtained.

Claims (5)

In a reaction solvent comprising water and an organic solvent, an alkoxide of silicon and / or a condensable compound derived from the alkoxide, and an alkoxide of a metal other than silicon, a condensable compound derived from the alkoxide, and In the method for producing silica-based composite oxide particles including the step of adding and reacting at least one selected from the group consisting of metal salts other than silicon, acetonitrile is used as at least one component of the organic solvent, and the reaction A method wherein the reaction is carried out while maintaining the concentration of acetonitrile contained in the liquid at 20% by mass or more. (1) From the group consisting of a silicon alkoxide and / or a condensable compound derived from the alkoxide, a metal alkoxide other than silicon, a condensable compound derived from the alkoxide, and a salt of a metal other than silicon Silica-based composite oxide particles comprising a step of mixing at least one selected, and (2) a step of adding and reacting the mixture obtained in the step to a reaction solvent containing water and an organic solvent. In the production method, acetonitrile is used as at least one component of the organic solvent, and the reaction is carried out while maintaining the concentration of acetonitrile contained in the reaction solution at 20% by mass or more. 3. The method according to claim 1, wherein the alkoxide of titanium and / or the alkoxide of zirconium is used as the alkoxide of a metal other than silicon. The method according to any one of claims 1 to 3, wherein silica-based composite oxide particles having a particle diameter variation coefficient of 7% or less are produced. 5. The method according to claim 1, wherein silica-based composite oxide particles having a particle circularity of 0.8 or more are produced.