JP2008037700A - Aggregate of silica-based compound oxide particle and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aggregate of silica-based compound oxide particles in which the content of metal oxides except for silica can be increased as high as over 50 mol% and the refractive index can be controlled to a high refractive index, with the particle diameters of particles constituting the aggregate being uniform. <P>SOLUTION: The aggregate of silica-based compound oxide particles comprises a compound oxide of silicon and at least one kind of metal selected from a group consisting of titanium, zirconium and aluminum and is characterized in that: (A) the silica compound oxide particles are spherical or substantially spherical particles having a circularity of 0.8 or more; (B) the coefficient of variation in the particle diameter size of the silica-based compound oxide particles is 30% or less; and (C) the number M of total gram atoms of at least one kind of metal selected from the group consisting of titanium, zirconium and aluminum and the number Si of gram atoms of silicon included in the silica-based compound oxide particles satisfy a relation of 0.5<M/(M+Si)<1.0. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a particle aggregate such as a powder of silica-based composite oxide particles and a method for producing the same. In particular, the present invention relates to a silica-based composite oxide particle aggregate having a high content of metal other than silicon, a method for producing the same, and a sol in which the particle aggregate is dispersed in a dispersion medium.

  As a method for producing inorganic oxide fine particles, a method of hydrolyzing and condensing a metal or metalloid alkoxide is known. This method is also called a sol-gel method, and depending on the reaction conditions, spherical fine particles can be produced in large quantities with the same particle diameter. For example, various sols and powders such as colloidal silica and spacer silica are manufactured by the sol-gel method using alkoxysilane as a raw material, and the particle size is arbitrarily adjusted in the nano-level to several μm range depending on the application. It is possible.

  The sol-gel method (or sol-gel method) broadly means a method for producing glass or ceramics having a sol-forming process and a gel-forming process. In the field of inorganic fillers, metal or metalloid alkoxides are used. A method for producing inorganic oxide particles by hydrolyzing and condensing azobenzene is sometimes called a sol-gel method (or sol-gel method). In the present invention, the term sol-gel method (or sol-gel method) is used for the latter meaning.

  In the sol-gel method, as a raw material, silicon alkoxide and metal alkoxide other than silicon are used in combination to produce so-called silica-based composite oxide particles such as silica-titania, silica-alumina, silica-zirconia, etc. In addition, the silica-based composite oxide particles obtained in this manner can exhibit various characteristic performances that cannot be obtained with particles composed of only silica. For example, the refractive index of the produced particles can be adjusted by changing the compounding ratio of silica and a metal oxide other than silica. Thus, for example, when used as a filler to be added to a resin material, the refractive index of the resin material and the filler By aligning the refractive index, the transparency of the resin material can be maintained.

  Patent Document 1 describes spherical silica-based composite oxide particles having a metal oxide content other than silica of 30 to 50 mol% and a particle diameter variation coefficient of 30% or less.

In addition, as another method for producing spherical silica-based composite oxide particles, a method called a VMC method using a deflagration phenomenon of metal powder (see Patent Document 2) or a method of introducing metal alkoxide into a flame in a liquid state There is. In this method, there is known a method (Patent Document 3) in which metal powder is introduced into an oxygen stream and burned and decomposed, and silica-based composite oxide particles can also be produced by these combustion methods.
JP 2003-252616 A Japanese Patent Publication No. 7-23202 Japanese Examined Patent Publication No. 7-61851

  In the field of resin-based optical materials, there is a demand for a resin that is transparent and has a high refractive index, and a resin that meets such a demand has been developed. For example, polyvinyl naphthalene and polyvinyl carbazole have a refractive index of 1.68, and polyethylene naphthalate has a refractive index of 1.75. It is expected that a resin having a higher refractive index will be developed in the future. When an inorganic filler is added to these resins to achieve high functionality without impairing transparency, particularly when a filler having a particle diameter longer than the wavelength of visible light is used, the refractive index of the resin and filler is set. It is necessary to align them, and a filler having a higher refractive index is required. It is also possible to change the refractive index by adding nanoparticles to the resin without compromising the transparency of the entire composite, and even when aiming to increase the refractive index by such a method, as a filler Is required to have a higher refractive index. However, since the silica-based composite oxide particles described in Patent Document 1 have a metal oxide content other than silica of 50 mol% or less, there is a limit to adjusting the refractive index of the filler to a high refractive index. was there.

  Moreover, regarding the inorganic oxide powder, depending on the application, it is required that the monodispersity of the particles constituting the powder is high. For example, when adding nanoparticles to a resin to form a composite and changing the refractive index without impairing the transparency of the entire composite, if particles having a large particle size are mixed, the transparency is impaired. In addition, the viscosity when a filler is added to a resin or monomer is affected by the particle size distribution of the filler to be added. If a highly monodisperse powder is used, (monodisperse) powders of various particle sizes are mixed. By doing so, it is possible to stably obtain a powder having a desired particle size distribution.

  However, in the combustion methods disclosed in Patent Documents 2 and 3, it is difficult to strictly control the particle diameter of the generated particles, and it is difficult to obtain a powder having high monodispersibility.

  Therefore, the present invention can make the content of metal oxides other than silica higher than 50 mol%, and can adjust the refractive index to a high refractive index. An object of the present invention is to provide a particle aggregate in which the particle diameters of the particles constituting the aggregate are uniform.

  As a result of intensive studies on the above problems, the present inventors have found that the hydrolysis rate of silicon alkoxides and metal alkoxides other than silicon is different and that the content of metal oxides other than silica is high. It has been found that this is an obstacle to the formation of physical particles. It was found that the above problems can be solved by forming particles by aligning the hydrolysis rate of silicon alkoxide and the hydrolysis rate of metal alkoxide other than silicon so as to be approximately the same. The present invention has been completed.

The first aspect of the present invention is an aggregate of silica-based composite oxide particles composed of a composite oxide of at least one metal selected from the group consisting of titanium, zirconium, and aluminum and silicon,
(A) The silica-based composite oxide particles are spherical or substantially spherical particles having a circularity of 0.8 or more,
(B) The coefficient of variation of the particle diameter of the silica-based composite oxide particles is 30% or less,
(C) When the total gram atom number of at least one metal selected from the group consisting of titanium, zirconium, and aluminum contained in the silica-based composite oxide particles is M, and the gram atom number of silicon is Si. A silica-based composite oxide particle aggregate satisfying a relationship of 5 <M / (M + Si) <1.0.

  The particle aggregate of the present invention comprises an aggregate of particles composed of a composite oxide of at least one metal selected from the group consisting of titanium, zirconium and aluminum, and the aggregate is a sol-gel. The individual particles constituting the aggregate are characterized by the characteristics of the particles obtained by the sol-gel method, that is, the characteristics that the particles are spherical or substantially spherical, more specifically, the particles It has the characteristic that the circularity of is 0.8 or more. Here, “circularity” is a value measured from a two-dimensional image of a particle, and is used as a scale representing the sphericity of the particle. The higher the circularity, the closer to the true sphere (the circularity of the true sphere is “1”). The circularity of the silica-based composite oxide particles constituting the particle aggregate of the present invention is more preferably 0.9 or more.

  In addition, since the particle aggregate of the present invention can be produced by a sol-gel method, the monodispersity is high, and the coefficient of variation of the particle diameter of the particles constituting the particle aggregate is as small as 30% or less. The variation coefficient of the particles is more preferably 20% or less, and further preferably 10% or less.

  Furthermore, the particles constituting the particle aggregate of the present invention are composed of at least one metal selected from the group consisting of titanium, zirconium, and aluminum (hereinafter, these metals are referred to as “specific foreign metals”, and their oxides are It may be referred to as “specific foreign metal oxide”) and a complex oxide of silicon. The composition is such that the value of the formula {M / (M + Si)} exceeds 0.5 and is less than 1.0. No silica-based composite oxide particles obtained by the sol-gel method have such a composition.

  The particle aggregate of the present invention can adjust its refractive index to a high refractive index when the silica-based composite oxide particles, which are constituent particles, have such a composition. Thereby, when used as a filler of a resin material having a high refractive index, the transparency of the resin material can be maintained by combining the refractive index of the filler and the refractive index of the resin material. As a specific use of the particle aggregate of the present invention, in addition to the use as a filler of the above-mentioned transparent resin, as an anti-glare film (AG film) light scattering particle, as an anti-blocking material (AB material) of a highly transparent film Can be mentioned.

  Further, among the particle aggregates of the present invention, those having an average particle diameter of 1 to 1000 nm are colloidally dispersed in a dispersion medium such as water or alcohol, and can be used as a sol. Such a sol is useful as a hard coating liquid material for plastic films and plastic lenses.

The second aspect of the present invention is a method for producing the silica-based composite oxide particle aggregate of the first aspect of the present invention,
(S1) a step of partially hydrolyzing silicon alkoxide with water to form a partially hydrolyzed product;
(S2) A composite alkoxide raw material obtained by mixing a complex prepared by mixing an alkoxide of at least one metal selected from the group consisting of titanium, zirconium, and aluminum with a complexing agent, and the partial hydrolyzate. And (S3) hydrolyzing and condensing the composite alkoxide raw material in a solvent or dispersion medium containing water,
In addition, the mixing of the complex and the partial hydrolyzate in the step (S2) is performed by adding M in total gram atoms of at least one metal selected from the group consisting of titanium, zirconium, and aluminum contained in the obtained composite alkoxide raw material. Silica-based composite oxide particle aggregate characterized by mixing so as to satisfy a relationship of 0.5 <M / (M + Si) <1.0 when the number of gram atoms of silicon is Si It is a manufacturing method.

  When particles are synthesized by the sol-gel method, it is common to go through a nucleation process in which nuclei are generated and a grain growth process in which the generated nuclei grow. Since the hydrolysis rate of the alkoxide of the specific foreign metal is much faster than the hydrolysis of the alkoxide of silicon, the composite oxide particles are formed by a sol-gel method using a simple mixture of the alkoxide of the specific different metal and the alkoxide of silicon. When trying to obtain, priority is given to the nucleation and grain growth of the oxide of a specific different metal. For this reason, especially when the content of the specific dissimilar metal is large, grain growth does not occur uniformly, and silica-based composite oxide particles having a high degree of circularity cannot be obtained.

  Therefore, in the present invention, a method is adopted in which the alkoxide of a specific dissimilar metal and a complexing agent are mixed to form a complex so that the hydrolysis rate is made to be the same as the hydrolysis rate of the silicon alkoxide. Then, silicon alkoxide is used as a partial hydrolyzate, and this is mixed with the above complex to prepare a composite alkoxide raw material in advance, and this is hydrolyzed / condensed to maintain the uniformity of the composition while maintaining the nucleus. By forming and growing this, silicon and the specific dissimilar metal are uniformly dispersed, and the content of the specific dissimilar metal defined by the formula {M / (M + Si)} is more than 0.5 and less than 1.0 The silica-based composite oxide particles can be obtained.

  The “solvent or dispersion medium containing water” is a solvent or dispersion medium containing 5 to 100 mass% of water based on the mass of the entire solvent or dispersion medium (100 mass%). Among these, when producing nanoparticles having a particle diameter of 1 nm to 100 nm, the water content is preferably 60 to 100% by mass, more preferably 70% by mass or more, and 75% by mass or more. More preferably it is. Further, in the case of obtaining silica-based composite oxide particles having monodispersibility and a high sphericity with a particle diameter of 100 nm or more, the water content is preferably 5 to 50% by mass, and 10 to 40 More preferably, it is mass%. In addition, when the particle diameter is 50 to 150 nm, even if the water content is 5 to 50% by mass and 60 to 100% by mass, respectively, it is desirable to appropriately select the conditions such as the organic solvent to be used and the temperature. Particles can be obtained.

  In the particle aggregate of the present invention, the silica-based composite oxide particles, which are the constituent particles, have the same characteristics as particles obtained by a conventional sol-gel method that are spherical or substantially spherical and have high monodispersibility. In addition, the specific dissimilar metal is included at a high content rate exceeding 0.5 in terms of the content rate. For this reason, it is possible to have a high refractive index that cannot be realized with a silica-based composite oxide obtained by a conventional sol-gel method. By using such composite particles, an inorganic oxide sol or The use of powder can be expanded.

  For example, by adding the particle aggregate of the present invention, it becomes possible to provide a resin material that is transparent and has a high refractive index. Since the silica-based composite oxide particles that are the constituent particles of the particle aggregate of the present invention can control the refractive index in the range of about 1.4 to 3, the particles have a particle diameter longer than the wavelength of visible light. Even when adding high-refractive-index resin to achieve high functionality (stiffness, reduction of thermal expansion coefficient, etc.), by aligning the refractive index of the resin material with the refractive index of the filler, the transparency of the resin material is improved. Can keep. It is also possible to improve the refractive index without compromising the transparency of the entire composite by adding the particle aggregate of the present invention consisting of nano-level silica-based composite oxide particles to the resin and compositing it. is there. Further, when used in combination with a low refractive index resin, the difference in refractive index can be increased, so that a high light scattering effect can be obtained. For this reason, the silica type complex oxide particle of this invention can be used conveniently also for the light diffusing plate of a liquid crystal display, etc.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
<Silica-based composite oxide particles and aggregates thereof>
Silica-based composite oxide particles that are constituent particles of the particle aggregate of the present invention are composed of silicon and a composite oxide of a metal other than silicon. Here, the metal other than silicon needs to be at least one (specific different metal) selected from the group consisting of titanium, zirconium, and aluminum. When the metal other than silicon is a specific dissimilar metal, its refractive index can be made higher than that of silica. The specific dissimilar metal is preferably titanium. Titanium alkoxides have a slower hydrolysis rate than other zirconium or aluminum alkoxides. Therefore, in the production method of the present invention described below, it is relatively easy to make the hydrolysis rate uniform with that of silicon alkoxide by forming a complex.

  The specific dissimilar metal may be formed into a composite oxide with silicon alone, or two or more specific dissimilar metals may be formed into a composite oxide with silicon. For example, both titanium and zirconium may be used as the specific dissimilar metal, and silica-titania-zirconia ternary silica-based composite oxide particles may be used, or both aluminum and titanium may be used as silica- Alumina-titania ternary silica-based composite oxide particles may be used.

  In the silica-based composite oxide particles, silicon and a specific dissimilar metal are present in a chemically-combined form in the form of a composite oxide (in other words, silicon is silicon, a specific dissimilar metal, or a specific dissimilar metal is oxygen. These constituent components cannot be physically separated from each other. The fact that both components are chemically bonded can be confirmed by measuring the infrared spectrum and refractive index (particle optical transparency). In the silica-based composite oxide particles, the dispersion state of silicon and the specific dissimilar metal is arbitrary, and may be uniformly dispersed at random, or microscopically the same type may be gathered. . In the latter case, a fine domain of silica or a specific dissimilar metal oxide (specifically, titania, zirconia, or alumina) is formed, but the domain is amorphous even if it is a crystal. Or a mixture of both. The crystallinity of the particles can be confirmed by means such as X-ray diffraction.

  Usually, most of the composite oxide particles obtained by the sol-gel method are amorphous, but in some cases, they are a mixture of amorphous and partially crystalline. Moreover, the crystallinity can be changed by firing these particles. Even if the particles before firing are amorphous, some or all of the constituent components can be made crystalline by firing at a high temperature.

  In general, when it is required to be optically transparent, the silica-based composite oxide particles constituting the particle aggregate of the present invention are preferably amorphous, and the particle diameter is particularly 40 nm or more. In this case, it is preferable that the whole is amorphous or only a very small part of the constituent components are converted to crystalline. For that purpose, it is preferable that the firing temperature at that time is 1100 ° C. or lower, particularly 1000 ° C. or lower, even if the particles are not fired.

  The silica-based composite oxide particles constituting the particle aggregate of the present invention according to the present invention are obtained when the total number of gram atoms of a specific different metal contained in the composite oxide particles is M and the number of gram atoms of silicon is Si. , M / (M + Si), the content of the specific different metal is in the range of 0.5 <M / (M + Si) <1.0. In the case of the ternary silica-based composite oxide particles as described above, M is the total number of grams of the specific dissimilar metal. The content of the specific dissimilar metal may be more than 0.5 and less than 1.0, but is preferably 0.51 to 0.99, particularly preferably 0.55 to 0.95 from the viewpoint of composition stability. .

  Si and M can be determined by quantitative analysis of constituent elements of the silica-based composite oxide particles of the present invention. Examples of the quantitative analysis method include a method in which the silica-based composite oxide particles of the present invention are dissolved with hydrofluoric acid and nitric acid, and the obtained solution is subjected to ICP emission analysis. Moreover, the content rate of a specific dissimilar metal can also be calculated | required by a fluorescent X ray analysis or Auger electron spectroscopy (AES). Although it is preferable to employ ICP emission analysis from the viewpoint of analysis accuracy, the content can be measured with an accuracy of about ± 0.005 even by fluorescent X-ray analysis or Auger electron spectroscopy (AES).

  In the conventional method for producing silica-based composite oxide particles by the sol-gel method, when trying to obtain a specific dissimilar metal content exceeding 0.5, the monodispersity of the particle diameter decreases, Since the particles are aggregated, particles having such a composition could not be produced. In the present invention, this problem is solved by improving the method for producing particles, and the silica-based composite oxide particles having a specific foreign metal content of more than 0.5 and less than 1.0, which has not been obtained conventionally. Succeeded in getting.

  The silica-based composite oxide particles constituting the particle aggregate of the present invention can have a refractive index adjusted to a high refractive index by having a specific dissimilar metal oxide at a high content. The refractive index of the particles can be controlled in the range of 1.4 to 3 by adjusting the kind and composition of the specific different metal.

  For example, when the specific dissimilar metal is titanium, when the titania content in the particles is changed, the refractive index of the particles changes almost linearly as shown in FIG. 1 (the relationship shown in FIG. Has been confirmed to hold). For specific different metals other than titanium, as in FIG. 1, the relationship between the specific foreign metal content and the refractive index of the particles is obtained in advance, and the specific different metal content is determined so that the desired refractive index is obtained. it can.

  Regarding the silica-titania composite oxide particles, when the titania content is more than 50 mol% and less than 100 mol% (Ti content is more than 0.5 and less than 1.0), the refractive index is changed. Adjustments can be made at about 1.8 to 2.8. Specifically, when each component is amorphous, the refractive index is 1.84 (titanium content: 0.51), the refractive index is 2.00 (titanin content: 0.7), and the refractive index is 2. Depending on the .16 (titanium content: 0.9 mol%) and the refractive index of the resin material to be added, composite oxide particles having various high refractive indexes can be formed. By heat-treating these, the refractive index can be further increased by crystallizing titania into a rutile type. In this case, the maximum refractive index is 2.8 (when the titanium content is 0.99).

  As described above, the silica-based composite oxide particles constituting the particle aggregate of the present invention can have a high refractive index that cannot be achieved by the silica-based composite oxide particles obtained by the usual sol-gel method. Therefore, for example, when used as a filler of a resin material having a high refractive index, the transparency of the resin material can be maintained by aligning the refractive index of the resin material and the refractive index of the filler. In addition, taking advantage of such characteristics, it can be used in various applications that require a high refractive index. The required refractive index varies depending on the application of the particle. When using the particle in an application where transparency must be maintained, a specific dissimilar metal is used so that the difference in refractive index between the material mixed with the particle and the particle becomes small. What is necessary is just to adjust the content rate of. On the other hand, when a high light scattering effect is required, the content of the specific dissimilar metal may be adjusted so that the difference in refractive index between the material mixed with the particles and the particles becomes large.

In addition, the silica-based composite oxide particles constituting the particle aggregate of the present invention can be adjusted to 1.5 to 1.5 by adjusting the kind and composition of the specific dissimilar metal or changing the firing temperature of the particles with respect to the true density. It can be controlled in the range of 5 g / cm ³ . The particle size of the silica-based composite oxide particles is in the range of 1 nm to 50 μm, preferably in the range of 5 nm to 5 μm, and more preferably in the range of 10 nm to 1 μm.

Since the particle aggregate of the present invention can be produced by a sol-gel method, the shape of the constituent particles is spherical or approximately spherical, and the circularity of the particles is 0.8 or more. Here, the “circularity” means that the particle area is S (μm ² ) when the particle is observed by using a scanning or transmission electron microscope or the like, and the result is image-processed. Is a value defined by “circularity” = (4πS) / (L ² ). Depending on the application, particles having a shape close to a true sphere may be desired. When used in such applications, the circularity of the silica-based composite oxide particles of the present invention is 0.9 or more, particularly It is preferable that it is 0.95 or more.

The particle diameter means “equivalent circle diameter” when particles are observed by using a scanning or transmission electron microscope or the like. The “equivalent circle diameter” is defined as “circle” when S (μm ² ) is the particle area when the observation result of a scanning or transmission electron microscope is image-processed, and L (μm) is the circumference of the particle. “Equivalent diameter” = (4S / π) ^1/2 .

  The silica-based composite oxide particles of the present invention have excellent characteristics as described above as individual particles. However, by adopting the sol-gel method, specifically the method of the present invention described later, the particle size can be reduced. Can be synthesized in large quantities. For this reason, the variation coefficient of the particle diameter of the silica-based composite oxide particles constituting the particle aggregate of the present invention can be set to 30% or less.

Here, the variation coefficient of the particle diameter is a scale indicating the monodispersity of the constituent particles contained in the particle aggregate, and is determined as follows. That is, 200 particles are observed with an electron microscope, the particle diameter of each particle is obtained by image processing, and the coefficient of variation is obtained from the obtained result. Incidentally, the coefficient of variation CV ^is represented by when the average particle size of all particles the standard deviation, the X and ^{U 1/2} in the particle size distribution ^{(U 1/2 / X) × 100} (%) The

  The variation coefficient of the particles constituting the particle aggregate of the present invention is more preferably 20% or less, and further preferably 10% or less.

  The particle aggregate of the present invention can be used not only as a powder but also as a sol. When used as a sol, examples of suitable dispersion media for the particle assembly of the present invention include water; alcohol compounds such as methyl alcohol, ethyl alcohol, and isopropanol; saturated hydrocarbons such as pentane, hexane, cyclohexane, and heptane. Compounds; aromatic hydrocarbon compounds such as toluene and xylene; ketone compounds such as acetone, methyl ethyl ketone and cyclohexanone; ester compounds such as ethyl acetate; amide compounds such as dimethylacetamide and dimethylformamide; diethyl ether, tetrahydrofuran and ethylene glycol diethyl Although ether compounds, such as ether and dioxane, can be mentioned, water or a mixture of water and a water-soluble alcohol is preferably used. These dispersion media are usually used in an amount of less than 3 times the total mass of the particle components.

  In the sol, the average particle diameter of the particle aggregate of the present invention dispersed in the dispersion medium is usually 1 nm to 1000 nm. It is difficult to produce particles having an average particle diameter of less than 1 nm. When the average particle diameter exceeds 1000 nm, the dispersibility is lowered and precipitation tends to occur. From the viewpoint of sol stability, the average particle diameter is preferably in the range of 3 nm to 800 nm, particularly 5 to 500 nm.

  Moreover, the average particle diameter in the case of using the particle aggregate of the present invention as a powder is usually 50 nm to 5000 nm. When the average particle size is less than 50 nm, it is difficult to handle, and when the average particle size is larger than 5000 nm, it takes time to produce this, and the dispersion of the particle size of the obtained particles becomes large (monodispersity is increased). May be difficult to maintain). From the viewpoints of ease of handling and ease of production, the average particle size of the powder is preferably in the range of 70 nm to 3000 nm, particularly 100 to 1000 nm.

  Here, the average particle diameter is a value obtained by observing the particles constituting the sol or powder with a scanning or transmission electron microscope, obtaining the equivalent circle diameter for any 200 particles, and averaging this. It is.

  In the sol or powder, since the shape of the particles is spherical, it is possible to lower the viscosity of the composite resin or increase the filling rate of the particles in the resin, for example, when filling the resin. It is. Further, when the coefficient of variation of the particle diameter is 30% or less, there is an effect that the viscosity of the composite resin can be easily controlled.

<Method for producing silica-based composite oxide particle aggregate>
FIG. 2 shows a process diagram of the method for producing a silica-based composite oxide particle aggregate of the present invention. The method for producing a silica-based composite oxide particle aggregate according to the present invention includes a step S1 of partially hydrolyzing a silicon alkoxide with water to form a partially hydrolyzed product, at least selected from the group consisting of titanium, zirconium, and aluminum. Step S2 of preparing a composite alkoxide raw material by mixing a complex prepared by mixing a alkoxide of a kind of metal (specific different metal) and a complexing agent and the partial hydrolyzate at a predetermined ratio, water It has process S3 which hydrolyzes and condenses a composite alkoxide raw material in the solvent or dispersion medium to contain.

  The production method of the present invention employs a sol-gel method in which particles are formed by hydrolysis and condensation of a metal alkoxide raw material. In the production method of the present invention, the hydrolysis rate of the alkoxide of the specific dissimilar metal and the hydrolysis rate of the silicon alkoxide are set to be approximately the same, and a predetermined method is obtained from the silicon alkoxide and the specific dissimilar metal alkoxide. The composite alkoxide raw material is formed in advance, and the composite alkoxide raw material is hydrolyzed / condensed under specific conditions, so that it contains a high content of an oxide of a specific dissimilar metal, and an oxide of silica and a specific dissimilar metal Can be produced in which silica-based composite oxide particles are uniformly dispersed. Hereinafter, each process of the present invention will be described.

(Partial hydrolyzate formation step S1)
The silicon alkoxide is partially hydrolyzed (step S1). As the silicon alkoxide, any known compound may be used without particular limitation as long as it forms a silicon oxide by hydrolysis / condensation reaction in a water-containing solvent or dispersion medium described below. it can. For example, a silicon alkoxide represented by the general formula Si (OR) ₄ or SiR ′ _n (OR) _4-n , or a low condensate obtained by partially hydrolyzing and condensing silicon alkoxide is industrially available. It is easy to do and is preferably used. These silicon alkoxides may be used in combination of two or more. In the above general formula, R and R ′ are alkyl groups, and are preferably lower alkyl groups such as a methyl group, an ethyl group, an isopropyl group, and a butyl group. n is an integer of 1 to 3.

  When partially hydrolyzing the silicon alkoxide, it is preferable to use an organic solvent such as alcohol compatible with both the alkoxide and water. Known organic solvents can be used without limitation, but alcohols such as methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol and propylene glycol, ketones such as acetone and methyl-ethyl ketone, dioxane, diethyl ether and the like A plurality of mixed solvents of ethers, esters such as ethyl acetate, and other organic solvents compatible with water are preferably used. When an organic solvent such as alcohol is not used, the silicon alkoxide and water tend to phase-separate, and partial hydrolysis may not proceed or the reaction may be very slow. Moreover, in order to advance partial hydrolysis rapidly, it is preferable to add a catalyst to the water. 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. As the acid concentration, it is preferable to use an acid having a pH in the range of 1 to 4. Unlike the case where an alkali catalyst is used, when an acid catalyst is used, it is difficult for condensation of the hydrolyzate to occur, so that the formation of particles before the step S2 can be prevented.

  Hereinafter, the matter considered by the present inventor as the mechanism of partial hydrolysis will be described. The case where tetramethyl silicate is used as the silicon alkoxide (alkoxysilane) will be described. By partial hydrolysis, a part of alkoxysilane is hydrolyzed and a silanol group (SiOH) is generated in the molecule (see the following formula (1)). In step S2, the silanol group reacts with a complex formed from an alkoxide of a metal other than silicon to generate a composite alkoxide of a metal other than silicon and silicon. The hydrolysis reaction of alkoxysilane proceeds sequentially, and it is considered that alkoxyhydroxysilane according to the following formula is generated as a main product according to the amount of water used. It is considered that the mixture has a distribution (mixture of compounds having different degrees of hydrolysis).

（式（１）において、「Ｍｅ」はメチル基を表している（以下、同様である。）。また、「ｎ」は１〜４の整数である。）

(In formula (1), “Me” represents a methyl group (hereinafter the same). “N” is an integer of 1 to 4.)

  In the production method of the present invention, the amount of water used when the silicon alkoxide is partially hydrolyzed with water is preferably controlled so that n is about 0.8 to 1.5. When the amount of water is less than the above range, the distribution of silica and specific dissimilar metal oxides in the particles may be non-uniform. When the amount is large, the composite alkoxide raw material is hydrolyzed and condensed to form a silica-based composite. When obtaining oxide particles, it tends to be difficult to control the reaction. For this reason, many fused particles are generated, or in extreme cases, particles may aggregate during particle synthesis.

On the other hand, as can be seen from the above formula (1), the amount of water used in the partial hydrolysis reaction of alkoxysilane is a factor that determines the number of silanol groups (Si—OH groups) introduced into the silane compound to be produced. The number of silanol groups contained in one molecule of the alkoxysilane partial hydrolyzate affects the uniformity of the composite alkoxide raw material prepared in step S2. That is, in the preparation step S2 of the composite alkoxide raw material, when the partial hydrolyzate and the complex formed from the alkoxide of the specific different metal are mixed, the alkoxy group and silanol group of the alkoxide in the complex react (dealcoholate). Reaction) to form Si—O—M ′ (wherein M ′ represents a specific dissimilar metal atom) bond, and Si _a · M ′ _b · (OR) _c · (OH) _d (where a, b, c, and d each represent the number of Si (silicon) atom, M ′ (specific heterogeneous metal) atom, OR group, and OH group contained in one molecule)) Is formed.

(Composite alkoxide raw material preparation step S2)
In the production method of the present invention, in step S2, a complex prepared by mixing an alkoxide of at least one metal (specific heterogeneous metal) selected from the group consisting of titanium, zirconium, and aluminum with a complexing agent; A composite alkoxide raw material is prepared by mixing the partial hydrolyzate prepared above so that the content of the specific different metal is 0.5 <M / (M + Si) <1.0.

  As described above, the hydrolysis rate of the alkoxysilane and the hydrolysis rate of the alkoxide of the specific dissimilar metal are greatly different. Therefore, when both are simply mixed and subjected to hydrolysis / condensation, the oxide of the specific dissimilar metal It is difficult to obtain composite oxide particles having a high content of and having a uniform composition. In the present invention, in order to equalize the hydrolysis rate of alkoxysilane and the hydrolysis rate of alkoxide of a specific foreign metal, a complex is formed by mixing the alkoxide of a specific different metal and a complexing agent. And this complex and the partial hydrolyzate of alkoxysilane are mixed, and a composite alkoxide raw material is prepared.

As the alkoxide of the specific different metal, titanium alkoxide (Ti (OR) ₄ ), zirconium alkoxide (Zr (OR) ₄ ), and aluminum alkoxide (Al (OR) ₃ ) can be used. R is an alkyl group, and is preferably a lower alkyl group such as a methyl group, an ethyl group, an isopropyl group, or a butyl group.

  As complexing agents, (1) alkylene glycols (ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, glycerol, etc.), (2) glycol alkyl ethers (ethylene glycol monoethyl ether, ethylene) Glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, etc.), (3) glycol aryl ethers (ethylene glycol monophenyl ether, etc.), (4) β-dicarbonyl Compound (acetylacetone, etc.), (5) Amines (ethylenediamine, diethanolamine) Triethanolamine), (6) hydroxy acetone, (7) acetals (acetone dimethyl acetal), (8) carboxylic acids (acetic, lactic, citric acid and the like) and the like can be used. Among these, amines such as triethanolamine, β-dicarbonyl compounds, hydroxyacetone, or carboxylic acids are preferably used. In particular, since the hydrolysis rate can be reduced with a relatively small amount, triethanolamine, diethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, ethanolamine, N-methylethanolamine, N-ethylethanolamine, acetic acid, Most preferably, at least one selected from the group consisting of hydroxyacetic acid, propionic acid, hydroxypropionic acid, and lactic acid is used.

  The complexing reaction can be performed by mixing an alkoxide of a specific different metal and a complexing agent in a polar solvent, preferably an alcohol. The reaction temperature may be 5 ° C. to the boiling point of the solvent, and the complexing reaction proceeds sufficiently even at room temperature. Moreover, although reaction time is based also on reaction temperature, it is about 10 minutes-about 2 hours normally.

  In the complexing reaction, the amount ratio between the alkoxide of the specific different metal and the complexing agent is important from the viewpoint of controlling the hydrolysis rate of the alkoxide of the specific different metal. In order to obtain composite oxide particles having a uniform composition, it is preferable to adjust the hydrolysis rate of the complex to be formed to the same level as the hydrolysis rate of the alkoxysilane. Since the hydrolysis rate of the complex can be controlled by changing the quantitative ratio between the alkoxide of the specific different metal and the complexing agent, the above viewpoints depend on the combination of the alkoxide of the specific different metal and the complexing agent to be used. From this, a suitable quantitative ratio may be determined as appropriate. Such a quantitative ratio can be easily determined by a simple experiment.

  In the following, tetraisopropyl titanate (also referred to as tetraisopropoxytitanium; hereinafter sometimes abbreviated as “TPT”) is used as the alkoxide of a specific dissimilar metal, and triethanolamine (hereinafter, “ An example of an experiment using “TEA” may be abbreviated as “TEA”.

  This experiment was conducted in order to confirm the relationship between the quantity ratio of TPT and TEA and the hydrolysis rate of the obtained complex, and was conducted according to the following procedure. That is, a 50 mass% methanol solution in which TPT and TEA were separately mixed in various proportions (molar ratio) of the same mass as the ammonia water was added to a predetermined amount of 0.3% ammonia water, It added at a stretch under the stirring (electromagnetic stirring) which was used, and the hydrolysis rate was evaluated by measuring the time from immediately after completion | finish of addition until a solution gelatinizes. In addition, the gelation time was calculated | required as the time of gelatinizing when the motion of the stirring bar stopped by the viscosity increase of the solution. The results at that time are shown in Table 1. In another experiment, when tetramethyl silicate was used as the silicon alkoxide and the experiment was performed under the same conditions, the gelation time was 14 minutes.

  From the above results, it was found that when TEA / TPT = 0.5, it was closest to the gelation time (14 minutes) when tetramethyl silicate was used. Thus, in the embodiment described below, TEA / TPT = 0.5. However, the idea of the present invention is to make the hydrolysis rate of an alkoxide of a specific different metal and the hydrolysis rate of a silicon alkoxide (alkoxysilane) at the same level. Therefore, if this idea is achieved, the blending ratio of TEA and TPT is not limited to the above value.

  In addition, when TEA / TPT = 0.5, when the TEA and TPT are mixed, the inventor believes that a complex represented by the following formula (2) is formed.

（式（２）において、「ｉＰｒ」はイソプロピル基を表している（以下、同様である。）。）

(In Formula (2), “iPr” represents an isopropyl group (hereinafter the same).)

  In step S2, a composite alkoxide raw material is prepared by mixing the complex prepared as described above and a partially hydrolyzed product of alkoxysilane. The mixing ratio of the partially hydrolyzed alkoxysilane and the complex is determined depending on what value the content of the specific different metal in the finally obtained silica-based composite oxide particles is desired. That is, based on the number of moles of Si atoms (gram atoms) contained in the partial hydrolyzate of alkoxysilane to be used, a specific different metal (M) required depending on the composition of the composite oxide particles to be obtained The number of moles of ') (the number of gram atoms) should be determined, and an appropriate amount of the complex should be used.

  For example, in the case of producing silica-based composite oxide particles having a titanium content of 0.8, assuming that the number of moles of silicon in the partial hydrolyzate is Si and the number of moles of titanium in the complex is Ti, {Ti The partial hydrolyzate and the complex are mixed so that /(Si+Ti)}=0.8.

  The composite alkoxide raw material can be suitably prepared by mixing a reaction solution obtained by partial hydrolysis of alkoxysilane and a complex solution under stirring. The liquid temperature during mixing is preferably maintained at 5 to 50 ° C. The stirring time depends on the reaction temperature, but about 10 minutes to 2 hours is sufficient.

  For example, when a reaction solution obtained by performing a partial hydrolysis reaction as shown in the following formula (3) and tetraisopropyl titanate (tetraisopropoxytitanium) which is an alkoxide of a specific different metal are mixed, the following formula It is considered that a complexing reaction as shown in (4) occurs and a part or all of tetraisopropyl titanate is complexed with alkoxysilane.

なお、式（４）においては、チタンのアルコキシドから形成した錯体を、単にチタンのアルコキシド（Ｔｉ（Ｏ−ｉＰｒ）_４）として省略記載している。

In the formula (4), a complex formed from titanium alkoxide is simply abbreviated as titanium alkoxide (Ti (O—iPr) ₄ ).

(Hydrolysis / condensation step S3)
In the method of the present invention, silica-based composite oxide particles are produced by hydrolyzing and condensing the composite alkoxide raw material prepared above in a solvent or dispersion medium containing water. When the composite alkoxide is hydrolyzed, it is condensed almost instantaneously to form a composite oxide.

  The "water-containing solvent or dispersion medium" used for hydrolysis / condensation is a solvent or dispersion containing 5 to 100% by weight of water based on the mass of the entire solvent (100% by weight). It is a medium. From the viewpoint of obtaining nanoparticles of 1 nm to 100 nm, the water content is preferably 60 to 100% by mass, more preferably 70% by mass or more, and even more preferably 75% by mass or more. . In addition, the content of water is preferably 5 to 50% by mass from the viewpoint of obtaining silica-based composite oxide particles having monodispersity and having a particle size of 100 nm or more and high sphericity. More preferably, it is 40 mass%. In addition, when the particle size is 50 to 150 nm, even if the water concentration ranges from 5 to 50% by mass and 60 to 100% by mass, respectively, it is desirable to appropriately select conditions such as the organic solvent to be used and temperature. Particles can be obtained.

  In addition, since water is consumed by the hydrolysis / condensation reaction of the composite alkoxide raw material and alcohol is produced as a by-product, the concentration of water in the solvent or dispersion medium decreases when the reaction is performed in batch, It is preferable to adjust so that the concentration of water in the solvent or dispersion medium is maintained in the above range from the start to the end of the reaction.

  When the water concentration of the solvent or dispersion medium is less than 100% by mass, the solvent or dispersion medium contains an organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol and propylene glycol, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane and tetrahydrofuran, and esters such as ethyl acetate. In addition, other organic solvents compatible with water are used alone or in combination. Among these, lower alcohols such as methanol, ethanol, and isopropanol are preferable because of high compatibility with metal alkoxides and water and low viscosity.

Further, as a catalyst for hydrolyzing the composite alkoxide, an amine such as N (CH ₃ ) _{3, a base} such as ammonia, LiOH, NaOH, KOH, N (CH ₃ ) ₄ OH can be suitably used. In particular, ammonia and amines are extremely suitable as a catalyst for hydrolysis because the produced silica-based composite oxide particles are calcined and no base remains in the particles. The amount of catalyst added varies depending on the type of catalyst used, the type of water and organic solvent in the water-containing organic solvent, and the blending ratio, but it cannot be said unconditionally, but added so that the pH is 10 or more, preferably 11 or more. It is preferable to do this. In the case of ammonia which is most suitable as a catalyst, it is preferable to add it so that the NH ₃ concentration in the reaction solution is in the range of 0.005 to 10% by mass, preferably 0.01 to 7% by mass.

  The composite alkoxide raw material is preferably dropped in the liquid. Dropping in liquid means that the tip of the dropping port is immersed in an aqueous solvent when the alkoxide raw material is dropped in the aqueous solvent. The position of the tip of the dropping 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. For example, when the liquid is dropped from above the reaction liquid without dropping in the liquid, it is not preferable because the particles easily aggregate.

  Moreover, you may add simultaneously the alkaline aqueous solution prepared separately with the said composite alkoxy raw material in a solvent or a dispersion medium. As the alkaline aqueous solution, 0.005 to 30% by mass of aqueous ammonia is suitable. In addition, it is alkaline with a supply ratio such that the number of moles of water in the alkaline aqueous solution is 1 to 6 times mole, preferably 2 to 5 times moles, with respect to the total number of moles of silicon and the specific foreign metal in the raw material. It is preferable to add the aqueous solution dropwise.

  Although it is not necessary to drop the alkaline aqueous solution in the liquid, dropping in the liquid near the stirring blade is preferable because stirring in the aqueous solvent 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 a synthesis with a high yield is possible.

  The composite alkoxide raw material is preferably dropped continuously or intermittently from the start to the end of the dropping. In addition, when adding intermittently, it is preferable not to leave the space | interval of 10 minutes or more, especially 3 minutes or more. The dropping speed is not necessarily constant, but it is desirable to change gradually when changing the dropping speed.

  The temperature of the reaction vessel when performing hydrolysis / condensation may be in the range of 0 to 50 ° C., and is appropriately selected depending on the type of alkoxide used. In addition, a well-known thing is employ | adopted as a reaction container used for hydrolysis and condensation, reaction conditions other than the above, without any limitation.

There are a plurality of methods for controlling the particle size of the particles produced in the hydrolysis / condensation, but in general, the particle size can be controlled by controlling the amount of the raw material used. For example, r _{0 is} the diameter of the particles synthesized preliminarily under certain conditions (temperature, stirring speed, solvent composition of the reaction solution, etc.), r is the target particle diameter, and the number of moles of all metal alkoxides used at this time. the When M _0, the number of moles of all of the metal alkoxide required to obtain particles with a particle size r becomes _{M 0 × (r / r 0} ) 3. That is, particles having a target particle diameter r can be obtained by reacting under the conditions used in the preliminary synthesis using ³ mol of M ₀ × (r / r ₀ ) raw material.

  It is also possible to control the particle size by adjusting conditions such as the amount of the reaction solution at the start of the reaction, the reaction temperature, and the composition of the reaction solution at the start of the reaction. In general, if the amount of the reaction solution is reduced, the particle size tends to increase, and if it increases, it tends to decrease. Further, when the reaction temperature is increased, the particle size tends to increase. Furthermore, since the particle size may change by changing the type of organic solvent used, it is possible to control the particle size using this.

  The particles after the synthesis are obtained as a particle dispersion dispersed in the reaction solution. Depending on the application, it may be used as it is, or after replacing the solvent of the reaction solution with an organic solvent such as water or alcohol. Further, after the particles are synthesized, they may be separated into solid and liquid by a method such as centrifugation, filtration, distillation, spray drying, etc. and taken out in the form of powder. The extracted powder can be dried. The drying temperature is preferably in the range of 50 to 300 ° C. The dried powder can be fired at higher temperatures. The firing temperature is preferably in the range of 100 to 1300 ° C., and the firing time is preferably in the range of 1 to 24 hours. When firing at a high temperature, the specific surface area of the particles tends to be small, and those dried at a low temperature tend to have a large specific surface area. When firing at a temperature exceeding 1300 ° C., the particles may sinter, and there is a concern that the monodispersibility may be impaired. The dried or fired particles can be crushed into individual particles using a ball mill, a jet mill or the like. The dried or fired particles can also be used after being dispersed in an appropriate solvent using a counter collision type dispersion device, a bead mill, or the like.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 (Production example of silica-based composite oxide nanoparticles having a titanium content of 0.51)
A 2 liter Erlenmeyer flask was charged with 152.2 g of methyl silicate (Si (OMe) ₄ , Tama Chemical Co., Ltd., trade name: normal methyl silicate), and 76.1 g of methyl alcohol and 0.04 mass with stirring. 18.0 g of% hydrochloric acid was added, and methyl silicate was partially hydrolyzed by stirring at room temperature for about 20 minutes (solution A).
Separately from the above, tetraisopropoxy titanium (Ti (OiPr) ₄ , Nippon Soda Co., Ltd., product name: A-1 (TPT)) 295.8 g, methanol 284.2 g and triethanolamine 149.2 g were added at room temperature. After stirring for 30 minutes, it was mixed with Solution A and stirred for 30 minutes (Solution B).
A reaction solution is prepared by mixing 1775.6 g of ion exchange water and 4.4 g of ammonia water (25 mass%) in a glass reaction vessel (internal volume 5 liters) with a stirrer, and the temperature of the reaction solution is 40 ° C. Retained. The reaction solution B was dropped into the solution over about 5 hours. After completion of the dropwise addition, stirring was further continued for 1 hour, and then the solution in the system was taken out, transferred to a 5-liter beaker, and allowed to stand. The obtained solution was concentrated twice with a reverse osmosis membrane, and then diluted with water to double. This concentration / dilution operation was repeated five times to obtain an aqueous dispersion of fine particles.
SEM observation was performed about the obtained particle | grains. As a result, particles having a particle size of 0.02 μm, a circularity of 0.92, and a coefficient of variation of 10% were obtained. Moreover, when the fluorescent X-ray analysis was performed about the powder obtained by drying the said aqueous dispersion, it turned out that the content rate of Ti is 0.51.

Example 2 (Production example of silica-based composite oxide nanoparticles having a titanium content of 0.7)
Into a 2 liter Erlenmeyer flask, 91.3 g of methyl silicate (Si (OMe) ₄ , Tama Chemical Industry Co., Ltd., trade name: normal methyl silicate) was charged, and while stirring, 45.7 g of methyl alcohol and 0.04 mass 10.8 g of% hydrochloric acid was added, and methyl silicate was partially hydrolyzed by stirring at room temperature for about 20 minutes (solution A).
Separately from the above, tetraisopropoxytitanium (Ti (OiPr) ₄ , Nippon Soda Co., Ltd., product name: A-1 (TPT)) 397.9 g, isopropyl alcohol 795.8 g and triethanolamine 208.8 g were added and room temperature was added. For 30 minutes and then mixed with solution A and stirred for 30 minutes (solution B).
A reaction solution is prepared by mixing 1775.6 g of ion exchange water and 4.4 g of ammonia water (25 mass%) in a glass reaction vessel (internal volume 5 liters) with a stirrer, and the temperature of the reaction solution is 40 ° C. Retained. The reaction solution B was dropped into the solution over about 5 hours. After completion of the dropwise addition, stirring was further continued for 1 hour, and then the solution in the system was taken out, transferred to a 5-liter beaker, and allowed to stand. The obtained solution was concentrated twice with a reverse osmosis membrane, and then diluted with water to double. This concentration / dilution operation was repeated five times to obtain an aqueous dispersion of fine particles.
SEM observation was performed about the obtained particle | grains. As a result, particles having a particle diameter of 0.01 μm, a circularity of 0.89, and a coefficient of variation of 14% were obtained. Further, when X-ray fluorescence analysis was performed on the powder obtained by drying the aqueous dispersion, it was found that the Ti content was 0.70.

Example 3 (Production example of silica-based composite oxide nanoparticles having a titanium content of 0.9)
Into a 3 liter Erlenmeyer flask, 17.6 g of methyl silicate (Si (OMe) ₄ , Tama Chemical Co., Ltd., trade name: normal methyl silicate) was charged, and 8.8 g of methyl alcohol and 0.04 mass were stirred. 2.0 g of hydrochloric acid was added, and methyl silicate was partially hydrolyzed by stirring at room temperature for about 20 minutes (solution A).
Separately from the above, tetraisopropoxytitanium (Ti (OiPr) ₄ , Nippon Soda Co., Ltd., product name: A-1 (TPT)) 294.4 g, isopropyl alcohol 588.4 g and triethanolamine 154.4 g were added and room temperature was added. For 30 minutes and then mixed with solution A and stirred for 30 minutes (solution B).
A reaction solution is prepared by mixing 1775.6 g of ion exchange water and 4.4 g of ammonia water (25 mass%) in a glass reaction vessel (internal volume 5 liters) with a stirrer, and the temperature of the reaction solution is 40 ° C. Retained. The reaction solution B was dropped into the solution over about 5 hours. After completion of the dropwise addition, stirring was further continued for 1 hour, and then the solution in the system was taken out, transferred to a 5-liter beaker, and allowed to stand. The obtained solution was concentrated twice with a reverse osmosis membrane, and then diluted with water to double. This concentration / dilution operation was repeated five times to obtain an aqueous dispersion of fine particles.
SEM observation was performed about the obtained particle | grains. As a result, particles having a particle diameter of 0.01 μm, a circularity of 0.83, and a variation coefficient of 22% were obtained. Further, when the powder obtained by drying the aqueous dispersion was subjected to fluorescent X-ray analysis, it was found that the Ti content was 0.90.

Examples 4 to 6 (Production examples of silica-based composite oxide nanoparticles having a titanium content of 0.7 with different complexing agents)
Particles were synthesized in the same manner as in Example 2 except that diethanolamine, methyl acetoacetate, and lactic acid were used instead of triethanolamine. Table 2 shows the properties of the obtained particles.

Example 7 (Production example of silica-based composite oxide nanoparticles having a zirconium content of 0.7)
Particles were synthesized in the same manner as in Example 2 except that tetra-n-butoxyzirconium was used instead of tetraisopropoxytitanium.
When the obtained particles were observed with an SEM, particles having a particle size of 0.02 μm, a circularity of 0.81, and a variation coefficient of 28% were obtained. Further, when X-ray fluorescence analysis was performed on the powder obtained by drying the aqueous dispersion, it was found that the Zr content was 0.70.

Example 8 (Production example of silica-based composite oxide nanoparticles having an aluminum content of 0.7)
Particles were synthesized in the same manner as in Example 2 except that aluminum sec-butoxide was used instead of tetraisopropoxytitanium.
When the obtained particles were observed with an SEM, particles having a particle size of 0.02 μm, a circularity of 0.82, and a variation coefficient of 24% were obtained. Moreover, when the fluorescent X-ray analysis was performed about the powder obtained by drying the said water dispersion liquid, it turned out that the content rate of Al is 0.70.

Example 9 (Production example of silica-based composite oxide 0.2 μm particles having a titanium content of 0.51)
A 2 liter Erlenmeyer flask was charged with 152.2 g of methyl silicate (Si (OMe) ₄ , Tama Chemical Co., Ltd., trade name: normal methyl silicate), and 76.1 g of methyl alcohol and 0.04 mass with stirring. 18.0 g of% hydrochloric acid was added, and methyl silicate was partially hydrolyzed by stirring at room temperature for about 20 minutes (solution A).
Separately from the above, tetraisopropoxy titanium (Ti (OiPr) ₄ , Nippon Soda Co., Ltd., product name; 295.8 g of A-1 (TPT), 568.5 g of isopropyl alcohol, and 74.6 g of triethanolamine were added at room temperature. After stirring for 30 minutes, it was mixed with Solution A and stirred for 30 minutes (Solution B).
A reaction solution was prepared by mixing 266.7 g and 133.3 g of acetonitrile and aqueous ammonia (25 mass%) in a glass reaction vessel (internal volume of 5 liters) with a stirrer, respectively. Held at 0C. The reaction solution B and 488.7 g of aqueous ammonia (25% by mass) were simultaneously added dropwise to the reaction solution. About 10 minutes after the start of dropping, the reaction solution started to become cloudy, and it was found that composite oxide particles were generated. All the raw materials were added dropwise over about 4 hours. After completion of the addition, stirring was further continued for 1 hour, and then the solution in the system was taken out and transferred to a 5-liter beaker and allowed to stand. The product was washed by repeating decantation several times using pure water as a solvent. The precipitate was dried and then calcined in air at 900 ° C. for 10 hours to obtain 130 g of inorganic oxide particles.
SEM observation was performed about the obtained particle | grains. As a result, it was found that the particles were highly monodisperse spherical particles having an average particle size of 0.2 μm, a coefficient of variation of 10%, and a circularity of 0.90 obtained from an electron microscope image.
Moreover, when the surface analysis of the said particle | grain was performed using Auger electron spectroscopy (AES) for confirmation, Si and Ti were detected from the surface layer of particle | grains, and the content rate of Ti is 0.70. I understood.

Example 10 (Production example of 0.2 μm particles of silica-based composite oxide having a titanium content of 0.7)
Into a 2 liter Erlenmeyer flask, 91.3 g of methyl silicate (Si (OMe) ₄ , Tama Chemical Industry Co., Ltd., trade name: normal methyl silicate) was charged, and while stirring, 45.7 g of methyl alcohol and 0.04 mass 10.8 g of% hydrochloric acid was added, and methyl silicate was partially hydrolyzed by stirring at room temperature for about 20 minutes (solution A).
Separately from the above, tetraisopropoxytitanium (Ti (OiPr) ₄ , Nippon Soda Co., Ltd., product name: A-1 (TPT)) 397.9 g, isopropyl alcohol 795.8 g and triethanolamine 104.4 g were added and room temperature was added. For 30 minutes and then mixed with solution A and stirred for 30 minutes (solution B).
A reaction solution was prepared by mixing 266.7 g and 133.3 g of acetonitrile and aqueous ammonia (25 mass%) in a glass reaction vessel (internal volume of 5 liters) with a stirrer, respectively. Held at 0C. To the reaction solution B and 600.9 g of ammonia water (25% by mass) were simultaneously added dropwise to the reaction solution. About 10 minutes after the start of dropping, the reaction solution started to become cloudy, and it was found that composite oxide particles were generated. All the raw materials were added dropwise over about 4 hours. After completion of the addition, stirring was further continued for 1 hour, and then the solution in the system was taken out and transferred to a 5-liter beaker and allowed to stand. The product was washed by repeating decantation several times using pure water as a solvent. The precipitate was dried and then fired in the air at 900 ° C. for 10 hours to obtain 140 g of inorganic oxide particles.
SEM observation was performed about the obtained particle | grains. As a result, it was found that the particles were highly monodisperse spherical particles having an average particle diameter of 0.2 μm, a coefficient of variation of 17%, and a circularity of 0.87 obtained from a photographed image taken by an electron microscope.
Moreover, when the surface analysis of the said particle | grain was performed using Auger electron spectroscopy (AES) for confirmation, Si and Ti were detected from the surface layer of particle | grains, and Ti content rate is 0.70. all right.

Example 11 (Production example of silica-based composite oxide 0.2 μm particles having a titanium content of 0.9)
Into a 3 liter Erlenmeyer flask, 17.6 g of methyl silicate (Si (OMe) 4, Tama Chemical Co., Ltd., trade name: normal methyl silicate) was charged, and 8.8 g of methyl alcohol and 0.04 mass were stirred. 2.0 g of hydrochloric acid was added, and methyl silicate was partially hydrolyzed by stirring at room temperature for about 20 minutes (solution A).
Separately from the above, tetraisopropoxytitanium (Ti (OiPr) ₄ , Nippon Soda Co., Ltd., product name: A-1 (TPT)) 294.4 g, isopropyl alcohol 588.4 g and triethanolamine 154.4 g were added and room temperature was added. For 30 minutes and then mixed with solution A and stirred for 30 minutes (solution B).
A reaction solution was prepared by mixing 266.7 g and 133.3 g of acetonitrile and aqueous ammonia (25 mass%) in a glass reaction vessel (internal volume of 5 liters) with a stirrer, respectively. Held at 0C. The reaction solution B and ammonia water (25% by mass) 438.4 g were simultaneously added dropwise to the reaction solution. About 10 minutes after the start of dropping, the reaction solution started to become cloudy, and it was found that composite oxide particles were generated. All the raw materials were added dropwise over about 4 hours. After completion of the addition, stirring was further continued for 1 hour, and then the solution in the system was taken out and transferred to a 5-liter beaker and allowed to stand. The product was washed by repeating decantation several times using pure water as a solvent. The precipitate was dried and then calcined in the air at 900 ° C. for 10 hours to obtain 80 g of inorganic oxide particles.
SEM observation was performed about the obtained particle | grains. As a result, it was found that the particles were highly monodisperse spherical particles having an average particle diameter of 0.2 μm, a coefficient of variation of 25%, and a circularity of 0.85 determined from a photographed image taken by an electron microscope.
Moreover, when the surface analysis of the said particle | grains was performed using Auger electron spectroscopy (AES) for confirmation, Si and Ti were detected from the surface layer of particle | grains, and Ti content rate is 0.90. all right.

Comparative Example 1
Particles were synthesized in the same manner as in Example 1 except that triethanolamine was not used. When SEM observation was performed on the obtained particles, it was revealed that the particles contained a large amount of particles having a circularity of 0.5 to 0.7.

Comparative Example 2
Particles were synthesized in the same manner as in Example 9 except that triethanolamine was not used. When SEM observation was performed on the obtained particles, it was revealed that the particles contained a large amount of particles having a circularity of 0.5 to 0.7.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the invention is limited to the embodiments disclosed herein. However, it can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and the silica-based composite oxide particle aggregate with such a change, its production method, and the A sol in which particle aggregates are dispersed in a dispersion medium should also be understood as being included in the technical scope of the present invention.

It is a graph which shows the relationship between a titania content rate and the refractive index of particle | grains. It is the schematic which shows the manufacturing process of the silica type complex oxide particle aggregate of this invention.

Explanation of symbols

S1 Partial hydrolyzate formation process S2 Compound alkoxide raw material preparation process S3 Hydrolysis / condensation process

Claims (3)

An aggregate of silica-based composite oxide particles composed of a composite oxide of at least one metal selected from the group consisting of titanium, zirconium, and aluminum and silicon,
(A) The silica-based composite oxide particles are spherical or substantially spherical particles having a circularity of 0.8 or more,
(B) The coefficient of variation of the particle diameter of the silica-based composite oxide particles is 30% or less,
(C) When the total number of gram atoms of at least one metal selected from the group consisting of titanium, zirconium, and aluminum contained in the silica-based composite oxide particles is M and the number of gram atoms of silicon is Si, 0 .5 <M / (M + Si) <1.0, a silica-based composite oxide particle aggregate characterized by satisfying the relationship of The sol in which the silica-based composite oxide particle aggregate according to claim 1 is dispersed in a dispersion medium, the particle aggregate having an average particle diameter of 1 to 1000 nm. A method for producing the silica-based composite oxide particle aggregate according to claim 1,
(S1) a step of partially hydrolyzing silicon alkoxide with water to form a partially hydrolyzed product,
(S2) A composite alkoxide raw material is prepared by mixing a complex prepared by mixing an alkoxide of at least one metal selected from the group consisting of titanium, zirconium and aluminum with a complexing agent and the partial hydrolyzate. And (S3) hydrolyzing and condensing the composite alkoxide raw material in a solvent or dispersion medium containing water,
In addition, the mixing of the complex and the partial hydrolyzate in the step (S2) is performed by calculating the total number of grams of gram atoms of at least one metal selected from the group consisting of titanium, zirconium, and aluminum contained in the obtained composite alkoxide raw material. The silica-based composite oxide particle aggregate is characterized by being mixed so as to satisfy a relationship of 0.5 <M / (M + Si) <1.0 when the number of gram atoms of silicon is Si. Production method.

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