JP2013177259A - Complex metal oxide particle and composition including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide complex metal oxide particles, which are particles of a complex metal oxide taking a perovskite-type crystal structure, wherein chemical stability of the complex metal oxide is excellent, a particle diameter thereof is small, and dispersibility thereof in a hydrophobic matrix is excellent.SOLUTION: Complex metal oxide particles include a complex metal oxide, and the complex metal oxide has elements A comprising one or more selected from Ba, Sr, Ca, Mg, Al, Pb, Co, and Sn, elements B comprising one or more selected from Ti, Zr, W, Nb, Hf, Sn, and Si, and oxygen O as constituent elements, wherein a particle diameter (2r) obtained by transmission microscopic observation is 1-70 nm, and a molar ratio k of (element A)/(element B) satisfies formulas (I)-(III). formula (I): {r+(r-d)}/(2×r)-0.3≤k, formula (II): k≤{r+(r-d)}/(2×r)+0.1, formula (III): k<0.98, wherein, r is a half value (nm) of the particle diameter (2r), and d is a size (nm) of a crystal lattice of the complex metal oxide.

Description

  The present invention relates to composite metal oxide particles and compositions containing the same.

For example, since titanium dioxide (TiO ₂ ) is a high refractive index / high dielectric constant material, it is promising as an additive for improving optical characteristics or electrical characteristics of a matrix made of an organic material or an organic-inorganic composite material.
The surface of metal oxide particles such as titanium dioxide particles is usually hydrophilic, whereas the organic material of the matrix is hydrophobic. There is known a method of subjecting the surface of physical particles to a hydrophobic treatment with a silane coupling agent or the like.

However, titanium dioxide has a photocatalytic activity, and there is a problem that adjacent organic materials are easily decomposed by light irradiation.
In contrast, for example, composite metal oxide particles having a perovskite crystal structure, such as barium titanate, strontium titanate, and barium strontium titanate, have titanium atoms and metal elements other than titanium (barium) sandwiching oxygen. , Strontium, etc.) alternately, there is no crystal structure of titanium dioxide that produces photocatalytic activity, and there is little risk of destroying adjacent organic materials.

A composite metal oxide having a perovskite crystal structure is represented by ABO ₃ (A and B are metal elements) as a typical composition formula (hereinafter referred to as a typical composition formula). A is mainly a metal element having a valence of +2, and B is a metal element having a valence of +4. A and B may each be composed of two or more kinds or may be partially substituted. FIG. 6 is a schematic diagram showing a crystal lattice having a perovskite crystal structure. In the figure, symbol A represents an atom of element A, B represents an atom of element B, and O represents an oxygen atom. In the figure, a, b, and c represent the triaxial directions of the crystal lattice, and d represents the crystal lattice size. In the composite metal oxide having a perovskite crystal structure, the total number of moles of element A and the total number of moles of element B are usually 1: 1.
Since the composite metal oxide having such a perovskite type crystal structure has a high dielectric constant, the composite metal oxide particles that have been hydrophobized are added with no photocatalytic activity to improve electrical characteristics. It can be expected as a material.
In particular, since barium titanate has a high refractive index, a product obtained by hydrophobizing barium titanate particles can be expected as an additive having no photocatalytic activity for improving optical characteristics.

As a general method for producing barium titanate, a hydrothermal method is known in which titanium oxide and barium hydroxide are heated and reacted in the presence of water.
Patent Document 1 describes a method for producing hydrophobized barium titanate particles suitable as high refractive index material particles for toner. Specifically, first, titanium hydroxide and a barium compound are reacted in a solvent containing water and alcohol to obtain a barium titanate precursor (first step), and the barium titanate precursor is heat-treated. (Second step) is a method in which barium titanate particles are obtained, and the barium titanate particles are subjected to a hydrophobizing treatment with a silane coupling agent (third step).

International Publication No. 2007/086451

The composite metal oxide particles used dispersed in the matrix are required to have a sufficiently small particle size so as not to impair the light transmission (transparency) of the matrix.
For example, the wavelength in the visible light region is defined as about 400 to 700 nm. Since light striking an object having a wavelength greater than about ¼ is scattered, it is considered that the light transmission (transparency) of the matrix is not impaired if the particle size of the additive is 70 nm or less.
However, particles obtained by a conventional hydrothermal method or a production method described in Patent Document 1 have a particle size that is too large to obtain good light transmission.
In the example of Patent Document 1, the synthesized barium titanate particles are pulverized with a coffee mill or the like and then hydrophobized with a silane coupling agent to obtain particles having a particle size of about 150 to 660 nm. The process for this is necessary, and the fineness of a particle size is still inadequate.

  Further, according to the knowledge of the present inventors, a conventional metal oxide having a perovskite crystal structure cannot be said to have sufficient chemical stability. For example, when pulverizing barium titanate particles, the particles were suspended in an acidic aqueous solution in order to promote peptization and reduce the particle size, so that the crystal structure of barium titanate was maintained. I could n’t help.

The present invention has been made in view of the above circumstances, and is a composite metal oxide particle having a perovskite crystal structure, wherein the composite metal oxide has good chemical stability and a small particle size. It is an object to provide product particles and a composition containing the same.
Preferably, composite metal oxide particles having a perovskite crystal structure, wherein the composite metal oxide has good chemical stability, small particle size, and good dispersibility in a hydrophobic matrix. An object of the present invention is to provide composite metal oxide particles and a composition containing the same.

The present inventors have found that the chemical stability of the perovskite type metal oxide (representative composition formula ABO ₃ ) is insufficient due to the strong ionicity of the element A. For example, the element A is complex in an acidic solution. It was thought that it might flow out from the metal oxide surface. As a result of extensive research, by controlling the molar ratio (k) and particle size (2r) of element A / element B so that the A element present on the particle surface of the perovskite-type metal oxide is reduced. The present inventors have found that chemical stability can be improved and have reached the present invention.

The present invention includes the following [1] to [3].
[1] Composite metal oxide particles containing a composite metal oxide, wherein the composite metal oxide is selected from one or more selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Sn. An element A consisting of Ti, Zr, W, Nb, Hf, Sn, Si, and an element B composed of one or more elements selected from the group consisting of Ti, Zr, and oxygen O.
The composite metal oxide particles have a particle size (2r) by transmission microscope observation of 1 to 70 nm,
A mixed metal oxide particle, wherein the molar ratio k of element A / element B satisfies the following formulas (I) to (III):
{R ³ + (r−d) ³ } / (2 · r ³ ) −0.3 ≦ k (I)
k ≦ {r ³ + (r−d) ³ } / (2 · r ³ ) +0.1 (II)
k <0.98 (III)
(In the formula, r is a half value (unit: nm) of the particle size (2r), and d is the crystal lattice size (unit: nm) of the composite metal oxide.)

[2] It further includes one or more silane coupling agent-derived components selected from the group consisting of a silane coupling agent, a hydrolyzate of the silane coupling agent, and a hydrolysis condensate of the silane coupling agent. Composite metal oxide particles.
[3] A composition comprising the composite metal oxide particles of [2] and an organic medium.

According to the present invention, there can be obtained composite metal oxide particles having a composite metal oxide having a perovskite crystal structure, wherein the composite metal oxide has good chemical stability and has a sufficiently small particle size. It is done.
The composite metal oxide particles further include one or more silane coupling agent-derived components selected from the group consisting of a silane coupling agent, a hydrolyzate of the silane coupling agent, and a hydrolyzed condensate of the silane coupling agent. When included, the composite metal oxide particles have a perovskite crystal structure, and the chemical stability of the composite metal oxide is good, the particle size is sufficiently small, and the dispersibility in a hydrophobic matrix is excellent. Good composite metal oxide particles can be obtained.
According to the present invention, a composition containing particles containing a composite metal oxide having a perovskite crystal structure and having good light transmittance can be obtained.

It is the graph which showed the area | region where the particle size (2r) of composite metal oxide particle | grains is 1-70 nm, and the molar ratio k of element A / element B satisfy | fills formula (I)-(III). It is an electron micrograph of the hydrophobized composite metal oxide particles obtained in the examples. It is an electron micrograph of the hydrophobized composite metal oxide particles obtained in the examples. It is an electron micrograph of the hydrophobized composite metal oxide particles obtained in the examples. It is an electron micrograph of the composite metal oxide particle obtained by the comparative example. It is a schematic diagram showing a crystal lattice of a perovskite crystal structure.

The composite metal oxide particles of the present invention include a composite metal oxide. The composite metal oxide includes at least one element A selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Sn, and Ti, Zr, W, Nb, Hf, Sn, Si, and the like. The element B composed of one or more selected from the group consisting of and oxygen O are used as the constituent elements. Such a composite metal compound having element A, element B, and oxygen O as constituent elements is a composite metal oxide having a perovskite crystal structure.
The element A is preferably composed of one or more selected from the group consisting of Ba, Sr, Ca, and Pb.
The element B is preferably composed of one or more selected from the group consisting of Ti, Zr, Sn, and Si, and more preferably composed of Ti and / or Zr.

In this specification, a composite metal compound including the element A, the element B, and the oxygen O as constituent elements is expressed as ABO ₃ (A and B are metal elements) and the like using a representative composition formula. Note that the representative composition formula is a formula for representing a combination of the element A and the element B, and does not mean that the molar ratio of the element A to the element B is 1: 1.
The composite metal oxide represented by the representative composition formula ABO ₃ may contain an additive element in addition to the constituent elements (element A, element B, oxygen O) as long as it has a perovskite crystal structure. Specifically, the additive element is an additive element that substitutes for the A site of ABO ₃ and / or an additive element that substitutes for the B site. As the additive element, a known additive element introduced into the composite metal oxide can be used for the purpose of stabilizing the crystal structure and suppressing charge transfer due to oxygen defects. For example, La, Bi, Y, Ce, Li, Na, Ag, and the like can be given as additive elements to be substituted at the A site, and Nb, Ta, Mn, Fe, Co, and the like can be given as additive elements to be substituted at the B site. , Ni, Cu and the like.
When the composite metal oxide contains an additive element, the upper limit of the content is not mainly constituting the composition of the composite metal oxide, and the additive element substituted for the A site is 1 mol% with respect to the element A. The following is preferable, and 0.1 mol% or less is more preferable. The additive element substituted for the B site is preferably 1 mol% or less, more preferably 0.1 mol% or less with respect to the element B.

A preferred example (representative composition formula) of a composite metal compound having the elements A, B and oxygen O as constituent elements in the present invention is shown below. In the following representative composition formula, 0 <x <1, 0 <y <1.
Barium titanate [BaTiO ₃ ],
Strontium titanate [SrTiO ₃ ],
Barium strontium titanate [(Ba _x Sr _1-x ) TiO ₃ ],
Calcium titanate [CaTiO ₃ ],
Barium zirconate titanate [Ba (Ti _y Zr _1-y ) O ₃ ],
Lead zirconate titanate [Pb (Ti _y Zr _1-y ) O ₃ ],
Zirconate titanate, barium strontium _{[(Ba x Sr 1-x} ) (Ti y Zr 1-y) O 3],
Barium calcium zirconate titanate [(Ba _x Ca _1-x ) (Ti _y Zr _1-y ) O ₃ ],
Barium zirconate [BaZrO ₃ ],
Strontium zirconate [SrZrO ₃ ],
Barium stannate [BaSnO ₃ ],
Strontium stannate [SrSnO ₃ ],
Barium silicate [BaSiO ₃ ] and the like.

The composite metal oxide particles of the present invention are selected from the group consisting of a silane coupling agent, a hydrolyzate of a silane coupling agent, and a hydrolysis condensate of a silane coupling agent in addition to the composite metal oxide. It is preferable that the above-mentioned component derived from a silane coupling agent is further included. In the present specification, particles containing a composite metal oxide and a component derived from a silane coupling agent may be referred to as hydrophobic composite metal oxide particles.
The hydrophobic composite metal oxide particles are more preferably composed of a composite metal oxide and a component derived from a silane coupling agent. However, the hydrophobized composite metal oxide particles composed of the composite metal oxide and the component derived from the silane coupling agent do not exclude those containing inevitable impurities.

The silane coupling agent may be an organosilicon compound having both a hydrophobic organic functional group contributing to reaction and interaction with an organic substance and a hydrolyzable group (alkoxy group) in one molecule, A known silane coupling agent can be used as appropriate.
For example, a silane coupling agent represented by the following formula (1) is preferable.
R ¹ _a Si (OR ² ) _b (1)
(In the formula, R ¹ is an organic functional group, OR ² is an alkoxy group having 1 or 2 carbon atoms, a is an integer of 1 or more, b is an integer of 1 or more, a + b = 4, and plural when a is 2 or more. And R ¹ may be the same as or different from each other. When b is 2 or more, the plurality of R ² may be the same as or different from each other.
In the formula (1), OR ² is preferably a methoxy group or an ethoxy group. b is preferably 3.
As the organic functional group in the formula (1), a known hydrophobic organic functional group in the silane coupling agent can be appropriately used. Examples of such organic functional groups include alkyl groups (some or all of hydrogen atoms may be substituted with halogen atoms such as fluorine atoms and chlorine atoms), phenyl groups, styryl groups, vinyl groups, (meth) An acryloxy group, an epoxy group, etc. are mentioned.

Examples of the silane coupling agent represented by the formula (1) include 3,3,3-trifluoropropyltrimethoxysilane, n-octadecyltrimethoxysilane, phenyltrimethoxysilane, 1,1,2,2-H. Tridecafluorooctyltriethoxysilane, styryltrimethoxysilane, vinyltrimethoxysilane, n-propyltrimethoxysilane, n-dodecyltrimethoxysilane, n-decyltrimethoxysilane, n-octyltrimethoxysilane, heptadecatrifluoro Examples include decyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane.
The hydrophobized composite metal oxide particles preferably contain at least a hydrolyzate of the silane coupling agent and / or a hydrolysis condensate of the silane coupling agent as a component derived from the silane coupling agent. A silane coupling agent that does not occur may be included.
In the hydrophobized composite metal oxide particles, it is preferable that a hydrolyzate and / or hydrolysis condensate of a silane coupling agent is chemically or physically bonded to the composite metal oxide, and is composed of the composite metal oxide. More preferably, the hydrolyzate and / or hydrolysis condensate of the silane coupling agent is chemically or physically bonded to the surface of the particles.

The particle diameter of the composite metal oxide particles of the present invention is 1 to 70 nm. When the thickness is 70 nm or less, the light transmission (transparency) of the matrix to which the particles are added is kept good. Preferably it is 60 nm or less. When the particle size is 1 nm or more, it is easy to produce, preferably 2 nm or more.
The particle diameter of the composite metal oxide particles in the present invention is a particle diameter measured by transmission microscope observation. That is, it is a value obtained by analyzing an observation image with a transmission microscope, reading the ferret diameter (number of pixels in the vertical and horizontal directions) for 100 particles from the image, and converting the mode value to nanometers (nm).
When the composite metal oxide particles are hydrophobized composite metal oxide particles containing a silane coupling agent-derived component, the surface of the particle (Y) made of the composite metal oxide having a perovskite crystal structure is derived from the silane coupling agent It is assumed that the component is present. Since the component derived from the silane coupling agent cannot be observed with a transmission microscope, the particle size of the hydrophobized composite metal oxide particles measured by the transmission microscope observation is the particle size (Y) of the composite metal oxide ( 2r).

In the composite metal oxide particles of the present invention, the molar ratio k of element A / element B contained in the particles satisfies the following formulas (I) to (III). FIG. 1 is a graph showing a region satisfying the following formulas (I) to (III) when the particle diameter (2r) is 1 to 70 nm and d is, for example, 0.4 nm. The horizontal axis represents the particle size (2r), and the vertical axis represents the element A / element B molar ratio k.
{R ³ + (r−d) ³ } / (2 · r ³ ) −0.3 ≦ k (I)
k ≦ {r ³ + (r−d) ³ } / (2 · r ³ ) +0.1 (II)
k <0.98 (III)

Formula (III) means that the number of moles of element A is less than 0.98, where the number of moles of element B contained in the particles is 1.
A conventional complex metal oxide having a perovskite crystal structure has an element A / element B molar ratio theoretically 1/1, and an element A / element B molar ratio present on the particle surface of the complex metal oxide. Is theoretically 1/1. On the other hand, when the molar ratio (k) of element A / element B is less than 0.98, there is little element A present on the particle surface of the composite metal oxide, and the hydrophobic composite with good chemical stability. Metal oxide particles are easily obtained. The molar ratio (k) of the above formula (III) is preferably 0.975 or less, more preferably 0.97 or less, and further preferably 0.95 or less.

“{R ³ + (r−d) ³ } / (2 · r ³ )” in the formulas (I) and (II) is an ideal case where the element A does not exist on the particle surface of the composite metal oxide. This is an expression representing the value of the molar ratio k of element A / element B, and is obtained as follows.
In the formula, r is a radius when the particle (Y) made of a composite metal oxide having a perovskite crystal structure is assumed to be spherical, and the unit is nm. A value of ½ of the particle size (2r) measured by the transmission microscope observation is used.
In the formula, d represents the crystal lattice size of the composite metal oxide, and is the length of one side of the cubic body having the same volume as the crystalline lattice when the crystal lattice is assumed to be a rectangular parallelepiped or a cubic body. d is a value determined according to the typical composition formula of the composite metal oxide, and its unit is nm.
In general, the crystal lattice size d is defined as “a ′”, “b ′”, and “c ′” (units are を), where the lengths of the crystal lattice in the three-axis directions (indicated by symbols “a”, “b”, and “c” in FIG. 6) are respectively “ The value calculated by the equation d = (a ′ × b ′ × c ′) ^(1/3) × 10 ”is ideal. The reason why the geometrical average of a ′, b ′, and c ′ is multiplied by 10 is to convert the unit from Å to nm. However, in this specification, instead of actually determining the lengths (a ′, b ′, c ′) in the three-axis directions, the plane distance calculated from the peak appearance position (2θ) obtained in the X-ray diffraction analysis is used. The crystal lattice size d was used.

In a particle (Y) made of a composite metal oxide having a perovskite crystal structure, as shown in FIG. 6, one crystal lattice constituting the particle (Y) has an atom of element A (hereinafter referred to as A 1 atom) and one element B atom (hereinafter referred to as B atom). Since the A atoms and B atoms are alternately present via oxygen atoms, if the molar ratio of element A / element B contained in the particles (Y) is 1/1, the particles (Y The crystal lattice that terminates at the A atom (that is, the A atom is at the outermost surface) and the crystal lattice that terminates at the B atom (that is, the B atom is at the outermost surface) It becomes one by one.
Of all the crystal lattices constituting the particle (Y), the “crystal lattice terminated with an A atom” contains one B atom and does not contain an A atom, and other crystal lattices contain an A atom and a B atom. Each one of the crystal lattices on the surface of the particle (Y) is terminated with B atoms, and an ideal state in which the element A does not exist on the surface of the particle (Y). It becomes.
The molar ratio k of element A / element B in this state is
k = (number of all crystal lattices−number of “crystal lattices terminated with A atoms”) / number of all crystal lattices = 1−number of “crystal lattices terminated with A atoms” / number of all crystal lattices Equation ( x).

Since the number of crystal lattices is proportional to the volume, the above formula (x) is replaced by the total volume of k = 1- “crystal lattice terminated with an A atom” / the total volume of particles (Y) (formula (x1)). .
The total volume of the particles (Y) is 4/3 · π · r ³ .
Since the crystal lattice terminated with A atom and the crystal lattice terminated with B atom are halved, the total volume of “crystal lattice terminated with A atom” is the volume of the crystal lattice existing on the surface of the particle (Y). One half of the total.
The total volume of the crystal lattice existing on the surface of the particle (Y) is a radius (rd) smaller than the radius (r) of the particle (Y) by d (crystal lattice size) from the total volume of the particle (Y). Is obtained by subtracting the volume of the sphere. That is,
4/3 · π · r ³ -4 / ³ · π · (r−d) ³
= 4/3 · π · {r ³ − (r−d) ³ }.
Therefore, the total volume of the “crystal lattice terminated with A atoms” is
4/3 · π · {r ³ − (r−d) ³ } ÷ 2.
Therefore, the equation (x1) is k = 1− [4/3 · π · {r ³ − (r−d) ³ } ÷ 2] / (4/3 · π · r ³ ).
And calculating this,
k = {r ³ + (r−d) ³ } / (2 · r ³ ) is obtained.

Therefore, theoretically, when the molar ratio of element A / element B is k = {r ³ + (r−d) ³ } / (2 · r ³ ), the composite metal oxide having a perovskite crystal structure is used. An ideal state in which the element A does not exist on the surface of the particles (Y) to be obtained is obtained.
Further, in consideration of various errors such as an error when the particle shape deviates from a sphere, an error when the crystal lattice shape deviates from a rectangular parallelepiped or a cubic body, and a measurement error, the molar ratio k is {r ³ + (r−d ) ³ } / (2 · r ³ ) −0.1 or more and {r ³ + (r−d) ³ } / (2 · r ³ ) +0.1 or less, equivalent to the above ideal state Is obtained.
Therefore, when the molar ratio k is {r ³ + (r−d) ³ } / (2 · r ³ ) +0.1 or less (formula (II)), the surface of the particles (Y) made of the composite metal oxide Hydrophobized composite metal oxide particles having sufficiently low element A and good chemical stability can be obtained.

On the other hand, when the molar ratio k is smaller than {r ³ + (r−d) ³ } / (2 · r ³ ), theoretically, A In this case, all of the crystal lattice existing on the surface of the particle becomes a crystal lattice terminated with B atoms, and the surface of the particle (Y) made of the composite metal oxide is included. Thus, a state in which the element A does not exist is obtained, so that good chemical stability is obtained.
However, it is preferable that the molar ratio k is not less than a certain point because electrical characteristics or optical characteristics due to the perovskite crystal structure can be sufficiently obtained. Therefore, the lower limit of the molar ratio k in the present invention is {r ³ + (r−d) ³ } / (2 · r ³ ) −0.3 or more (formula (I)).
Preferably, the molar ratio k is in the range of 0.5 or more, and the above formulas (I) to (III) are preferably satisfied.

Hydrophobized composite metal oxide particles containing a silane coupling agent-derived component can be produced without the pulverization step by the following composite metal oxide particle production method (Z).
<Method for producing composite metal oxide particles (Z)>
According to a conventional hydrothermal method, an oxide of element B (for example, titanium oxide) and a hydroxide of element A (for example, barium hydroxide) are reacted in the presence of water to react with ABO ₃ ( For example, after synthesizing BaTiO ₃ ), a silane coupling agent treatment is performed to produce hydrophobized composite metal oxide particles, whereas the composite metal oxide particle production method (Z) is used for synthesis. This is a method in which oxide particles of element B are treated with a silane coupling agent before reacting with element A.

Hereinafter, an embodiment of the present method (Z) will be described.
The first embodiment is an embodiment in which the element B in the composite metal oxide is one kind, and the first step of treating the oxide particles of the element B with a silane coupling agent, This is a method for producing composite metal oxide particles, comprising a second step of reacting a product obtained in the step (hereinafter sometimes referred to as a first product) with a hydroxide of element A.
The second embodiment is an embodiment in which the element B in the composite metal oxide is composed of two or more types, and the oxide particles of any element B ′ that is the element B are treated with a silane coupling agent. A second step of reacting the first step, the product obtained in the first step (first product), a hydroxide of element A, and a compound containing element B other than element B ′; It is a manufacturing method of the composite metal oxide particle which has a process.

(First embodiment)
The present embodiment will be described by taking as an example a case where the element B in the composite metal oxide is composed only of titanium (Ti).
[Oxide particles of element B]
In this embodiment, titanium oxide (hereinafter sometimes referred to as titania) particles are used as the element B oxide particles. It is preferably used in the form of an aqueous dispersion containing titanium oxide particles. The aqueous dispersion containing the titanium oxide particles is preferably acidic or alkaline in terms of sufficiently hydrolyzing the alkoxy group of the silane coupling agent. Specifically, when acidic, the pH is preferably 1 to 5. When alkaline, the pH is preferably 8 to 14.
The particle size (2r) of the hydrophobized composite metal oxide particles obtained in the second step described later can be controlled by the primary particle size of the titanium oxide particles.
In order to make the particle size (2r) of the hydrophobized composite metal oxide particles 70 nm or less, the primary particle size of the element B oxide particles is preferably 56 nm or less, and more preferably 48 nm or less. The lower limit is preferably 1 nm or more, more preferably 2 nm or more, from the viewpoint that a state of fine particles in which a large number of raw material elements are collected is easily obtained.
The aqueous dispersion containing the titanium oxide particles having the preferred particle diameter is available from commercial products.
The titanium oxide particles may be aggregated. In the case of agglomeration, the primary particle size may be in the above range, and the secondary particle size is not particularly limited. In order to obtain the light transmission (transparency) of the matrix to which the hydrophobic composite metal oxide particles are added, the secondary particle size is preferably 100 nm or less, and more preferably 80 nm or less.

[First step]
In this step, the titanium oxide particles are treated with a silane coupling agent. The treatment with the silane coupling agent means that the hydrolyzate and / or hydrolysis condensate of the silane coupling agent is chemically or physically bound to the surface of the particle.
In this step, the silane coupling agent treatment is preferably performed in the presence of water and alcohol.
Specifically, an aqueous dispersion containing titanium oxide particles, an alcohol, and a silane coupling agent are mixed and stirred to form a mixed solution, and the liquid temperature of the mixed solution is maintained at about 15 to 45 ° C. Hydrolyze reaction. The holding time is, for example, about 1 to 16 hours depending on the silane coupling agent.
Examples of the alcohol include methanol, ethanol, propanol, isopropanol, butanol, hexafluoroisopropanol and the like. These may be used alone or in combination of two or more. Ethanol is preferable because water in the aqueous dispersion containing the titanium oxide particles can be efficiently removed by azeotropic distillation.

The content of the alcohol in the mixed solution is preferably 50 to 400% by volume, more preferably 100 to 200% by volume with respect to the aqueous dispersion containing titanium oxide particles. When the alcohol content is not more than the upper limit of the above range, the hydrolysis rate of the silane coupling agent is sufficiently obtained, and when it is not less than the lower limit, the silane coupling agent is easily compatible with the system.
1-30 mass% is preferable with respect to the sum total of an aqueous dispersion and the said alcohol, and, as for content of the titanium oxide particle in the said liquid mixture, 2-15 mass% is more preferable. When the content of the titanium oxide particles is less than or equal to the upper limit of the above range, aggregation is easily avoided, and when the content is greater than or equal to the lower limit, the titanium oxide particles are sufficiently treated with the silane coupling agent.
The content of the silane coupling agent in the mixed solution is 0.8 to 1.6 with respect to a value obtained by multiplying the total surface area (m ² ) of the obtained hydrophobic composite metal oxide particles by 6 μmol / m ^2. Molar equivalent is preferable, and 1.0 to 1.4 molar equivalent is more preferable. When the silane coupling agents are densely arranged on the plane (solid surface), the density of one layer of the silane coupling agent in contact with the plane is approximately 6 μmol / m ² . The total surface area (m ² ) of the hydrophobized composite metal oxide particles can be determined by trial manufacture of the particles in advance.
When the content of the silane coupling agent is not more than the upper limit of the above range, a side reaction with the element A hardly occurs, and when it is more than the lower limit, good dispersibility of the hydrophobized composite metal oxide particles can be easily obtained.

The reaction solution obtained by reacting the silane coupling agent with the titanium oxide particles in this way is obtained by subjecting the titanium oxide particles (first product) to be treated with the silane coupling agent after solvent substitution as necessary. The organic solvent dispersion may be used in the next step. Alternatively, the solvent of the reaction solution may be distilled and then dried to obtain a dried product of the first product, and an organic solvent dispersion obtained by dispersing this in an organic solvent may be used in the next step.
As the organic solvent in the organic solvent dispersion of the first product, those mentioned as the organic solvent in the reaction liquid in the second step described later are preferable.

The content of the first product (titanium oxide particles treated with the silane coupling agent) in the organic solvent dispersion of the first product is 0.5 to 30 mass excluding the alkali agent described later. % Is preferable, and 1 to 15% by mass is more preferable. Aggregation is easily avoided when the content of the first product is not more than the upper limit value of the above range, and efficient productivity is obtained when the content is not less than the lower limit value.
The organic solvent dispersion of the first product is preferably made alkaline by adding an alkali agent. By making the organic solvent dispersion of the first product alkaline, it is possible to avoid decomposition of the silane coupling agent, which is an organic substance, under the heating conditions in the second step described later, and to condense the silanol groups. Can be promoted. Specifically, the pH of the organic solvent dispersion of the first product is preferably 7 or more, and more preferably 8 or more. The upper limit of the pH is preferably 14 or less and more preferably 12 or less in the first step from the viewpoint that the fine particles can be easily dispersed.
Examples of the alkaline agent include ammonia alcohol solutions such as a mixed solution of an ammonia aqueous solution and ethanol, ammonia methanol, and the like.

[Second step]
In this step, the first product (titanium oxide particles treated with the silane coupling agent) obtained in the first step is reacted with the hydroxide of element A. As a result, particles containing a composite metal oxide composed of titanium (Ti), element A, and oxygen O and a component derived from a silane coupling agent (hereinafter sometimes referred to as a second product) are generated.
This reaction is preferably carried out by a method of heat treatment in the presence of water and an organic solvent. Specifically, the reaction liquid containing the first product obtained in the first step, the hydroxide of element A, water, and an organic solvent is heat-treated. When there are two or more elements A constituting the composite metal oxide, the reaction liquid contains the respective hydroxides of the two or more elements A.
Examples of the organic solvent in the reaction solution include ketones such as methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), methyl isoamyl ketone, cyclohexanone, and propylene glycol monomethyl ether acetate (PGMEA); hydrocarbon compounds such as toluene and hexane; Alcohols such as methanol, ethanol, propanol, isopropanol, butanol; perfluorotributylamine, 1, 1, 1, 2, 3, 4, 4, 5, 5, 5-decafluoro-3-methoxy-2- (trifluoro And fluorine-containing solvents such as methyl) pentane. These may be used alone or in combination of two or more.
The first product obtained in the first step is preferably used in the form of an organic solvent dispersion of the first product.

The molar ratio of element A to element B (Ti in this embodiment) present in the reaction solution in this step (element A / element B) is within the range of less than 0.98, and the hydrophobic composite metal to be obtained It is preferable to set according to the molar ratio k of the oxide particles.
In this method, it is possible to obtain hydrophobic composite metal oxide particles having a molar ratio k of less than 0.98 even when the molar ratio of element A / element B in the reaction solution is 0.98 or more. However, in that case, an excess A element that does not constitute the crystal structure of the particles is generated, and therefore a range of less than 0.98 is efficiently preferred.

The content of water in the reaction solution is preferably 5 to 50% by volume, more preferably 10 to 35% by volume with respect to the total amount of the reaction solution. However, when the alkali agent added at the final stage of the first step described above includes water, the water content here includes the water in the alkali agent. If the water content is not more than the upper limit of the above range, the second product can be easily distributed to the solvent phase, and if it is not less than the lower limit, a place where the hydroxide of the element A dissolves is sufficiently provided.
The reaction solution preferably contains an alcohol in terms of promoting the separation of the aqueous phase and the solvent phase after the reaction. Preferably it contains ethanol. The alcohol content in the reaction solution is preferably 30 to 400% by volume, more preferably 50 to 300% by volume with respect to the amount of water. If the alcohol content is less than or equal to the upper limit of the above range, a uniform phase does not occur and separation occurs, and if the alcohol content is greater than or equal to the lower limit, the reaction solution is prevented from emulsifying and becoming insoluble. However, when emulsified, it can be separated by adding an appropriate amount of alcohol.
The content of the organic solvent other than alcohol in the reaction solution is the content of the first product (the titanium oxide particles treated with the silane coupling agent) in the reaction solution. It is preferable to appropriately set the content of the first product (titanium oxide particles treated with the silane coupling agent) in the organic solvent dispersion liquid.

The heat treatment of the reaction liquid in this step can be performed by a known method. For example, a method of irradiating the reaction solution with microwaves, a method of heating in an autoclave, or the like can be used. The heating conditions may be in a range where a desired composite metal oxide can be obtained. When heating is insufficient, the formation of crystals of the composite metal oxide does not proceed, and when heated excessively, the silane coupling agent tends to be decomposed or particles are aggregated. In the heat treatment, it is preferable to involve stirring.
For example, the temperature of the reaction solution (reaction temperature) is preferably 50 to 250 ° C, more preferably 80 to 200 ° C. However, when heating is performed by microwave irradiation, the particle surface is preferentially heated, so the local actual temperature is unknown, and the microwave irradiation amount is controlled by the temperature of the reaction solution. The time for holding the reaction temperature (holding time) is preferably about 0.5 to 60 minutes, more preferably about 1 to 30 minutes in the case of direct heating by microwave irradiation after reaching a predetermined temperature. In the case of indirect heating by an autoclave or the like, about 0.5 to 72 hours is preferable, and about 1 to 48 hours is more preferable.

  After completion of the heat treatment, the reaction solution is cooled, for example, by natural cooling (cooling), and allowed to stand, and an organic solvent phase (upper phase) containing the target second product (hydrophobized composite metal oxide particles). And phase separation into an aqueous phase (lower phase). This is separated, and the obtained organic solvent phase is dried, whereby a desired dried product of the second product can be obtained.

You may refine | purify after a 2nd process as needed.
For example, the obtained dried product of the second product may be purified by a method in which it is dissolved or dispersed in an organic solvent and centrifuged. Thereby, for example, coarse particles having a particle size of about 100 nm or more can be removed.

According to the production method of the present embodiment, as shown in the examples described later, the particle size is sufficiently small as 70 nm or less, without pulverization after synthesis, and derived from the composite metal oxide and the silane coupling agent. Hydrophobized composite metal oxide particles that contain the components and satisfy the above formulas (I) to (III) are obtained.
As shown in Examples described later, the obtained hydrophobized composite metal oxide particles are stable even in an acidic solution and excellent in chemical stability. Therefore, the product obtained in step (2) can be washed with an aqueous solution of an acidic solution such as an acetic acid aqueous solution, thereby removing excess element A that does not constitute the crystal structure of the composite metal oxide. it can.

Further, as shown in the examples described later, when hydrophobized composite metal oxide particles obtained by reacting element A with titanium oxide after silane coupling were analyzed by X-ray diffraction, peaks derived from titanium oxide were obtained. Is not observed, and a peak of a composite metal oxide having a perovskite crystal structure composed of element A, titanium, and oxygen is observed. Furthermore, the obtained hydrophobized composite metal oxide particles exhibit good dispersibility in a hydrophobic organic solvent.
From these facts, the hydrophobized composite metal oxide particles obtained by the production method of the present embodiment have a silane coupling agent hydrolyzate and / or hydrolyzate on the surface of the composite metal oxide particles having a perovskite crystal structure. It is assumed that the decomposition condensate is chemically or physically bound.

Such hydrophobized composite metal oxide particles have high dielectric constant, no photocatalytic activity like titanium oxide, good chemical stability, small particle size, dispersibility in hydrophobic matrix Therefore, it is suitable as an additive for improving the electrical characteristics without deteriorating the light transmittance of the matrix.
In particular, barium titanate has a high refractive index, no photocatalytic activity like titanium oxide, good chemical stability, small particle size, and good dispersibility in a hydrophobic matrix. It is suitable as an additive for improving the optical characteristics without lowering the light transmittance.

In this embodiment, by treating the oxide particles of element B with a silane coupling agent before reacting with element A, the particle size is small when reacted with element A, and the above formulas (I) to (I) The reason why the hydrophobized composite metal oxide particles satisfying III) are generated is considered as follows.
As shown in the examples described later, according to the production method (Z), the molar ratio (element A / element B) of element A to element B in the reaction solution in the second step is 1/1 (= 1). ), The molar ratio (element A / element B) is less than 1 when elemental analysis is performed after the obtained composite metal oxide particles are washed with an acidic aqueous solution. From this, the element B on the particle surface of the first product obtained in the first step (the oxide particles of the element B treated with the silane coupling agent) contains a hydrolyzate of the silane coupling agent and Since the hydrolysis condensate is bonded, the element B is easily held at the particle surface position during the reaction with the hydroxide of the element A. As a result, in the second step, the silane coupling agent is used. It is presumed that composite metal oxide particles in which the element A is incorporated inside the element B on the surface bonded to the hydrolyzate and / or the hydrolysis condensate are generated. Therefore, it is considered that the A element existing on the surface of the particle made of the perovskite type composite metal oxide is reduced, and the hydrophobic composite metal oxide particles satisfying the above formulas (I) to (III) can be obtained.
Further, the particle size of the obtained hydrophobized composite metal oxide particles is slightly larger than that of the element B oxide particles, but the hydrolyzate and / or hydrolysis condensate of the silane coupling agent is bonded to the surface. Therefore, it is considered that the hydrophobized composite metal oxide particles having a small particle size are hardly obtained.

In this embodiment, when the element B in the composite metal oxide is only titanium (Ti), the titanium oxide particles are used in the first step. However, the element B in the composite metal oxide is titanium ( When only the element B other than Ti) is used, oxide particles of the element B other than titanium are used instead of the titanium oxide particles.
Even in this case, the oxide particles of the element B used for the synthesis are treated with a silane coupling agent before reacting with the element A, so that the pulverization is not performed after the synthesis as in the first embodiment. Hydrophobized composite metal oxide particles satisfying the above formulas (I) to (III) containing a composite metal oxide and a component derived from a silane coupling agent are obtained.

(Second Embodiment)
In the present embodiment, an embodiment in which the element B in the composite metal oxide is composed of two or more types will be described.
That is, in the first embodiment, the element B in the composite metal oxide is only titanium. For example, the element B in the composite metal oxide is composed of titanium and one of the elements B other than titanium. In the second step, the first product (titanium oxide particles treated with the silane coupling agent) obtained in the first step, the hydroxide of element A, and the element B other than titanium are combined. The compound containing is reacted.
That is, the heat treatment is performed by adding a compound containing an element B other than titanium to the reaction solution in the second step. When there are two or more elements B other than titanium, the reaction solution contains a compound containing each of the two or more elements B.
Thereby, the hydrophobized composite metal oxide particles (second generation) including the composite metal oxide composed of titanium (Ti), the element B other than titanium, the element A, and the oxygen O and the silane coupling agent-derived component. Product).

Examples of the compound containing element B other than titanium used in the second step include zirconyl nitrate (zirconium nitrate dihydrate), sodium tungstate, niobium chloride, hafnium chloride, tin chloride, tetramethoxysilane and the like. It is done.
Also in this embodiment, the titanium oxide particles used for the synthesis are treated with a silane coupling agent before reacting with the element A, so that the particles can be obtained without pulverization after the synthesis as in the first embodiment. Hydrophobized composite metal oxide particles having a sufficiently small diameter of 70 nm or less, satisfying the above formulas (I) to (III), good chemical stability, and good dispersibility in a hydrophobic matrix Is obtained.

In this embodiment, when titanium (Ti) is contained in two or more kinds of elements B in the composite metal oxide, titanium oxide particles are used in the first step, but instead of this, other than titanium. Element B oxide particles may be used.
Also in this case, the oxide particles of the element B used for the synthesis are treated with a silane coupling agent before reacting with the element A, so that the pulverization is not performed after the synthesis as in the second embodiment. Hydrophobized complex metal oxide having a sufficiently small particle size of 70 nm or less, satisfying the above formulas (I) to (III), good chemical stability and good dispersibility in a hydrophobic matrix Product particles are obtained.

<Composition>
The composition of the present invention comprises hydrophobized composite metal oxide particles and an organic medium.
The hydrophobized composite metal oxide particles are excellent in chemical stability, have good dispersibility in an organic medium, and can maintain the light transmittance of the organic medium, and thus can be contained in various compositions.
Preferable uses of the composition of the present invention include, for example, a composition for a dielectric layer of a touch panel, a polymer multilayer capacitor, an optical member for aberration correction, and a material for a diffraction grating.
The content of the hydrophobized composite metal oxide particles in the composition of the present invention can be appropriately set according to the use or usage method of the composition, for example, within a range of 10 to 80% by mass. It is preferable to do.

When the composition of the present invention is a composition for a dielectric layer of a touch panel, it contains an organic medium selected from polyethylene terephthalate (PET), acrylic resin, epoxy resin, silicone, and polycarbonate, and hydrophobized composite metal oxide particles. preferable. Furthermore, it is preferable to contain stabilizers, such as a radical trap agent.
Further, as a typical composition formula of preferable hydrophobized composite metal oxide particles, barium titanate (BaTiO ₃ ) is used for a high refractive index, and barium zirconate titanate-barium calcium titanate is used for a high dielectric constant. mixed crystal _{[(Ba x Ca 1-x} ) (Ti y Zr 1-y) O 3] and the like.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
The raw materials used in the following examples are as follows.
Titania (A): manufactured by Sakai Chemical Co., Ltd., titanium dioxide aqueous dispersion (primary particle size 5 nm, solid content concentration 15 mass%, specific gravity 1.11, pH 3)
Titania (B): manufactured by Ishihara Sangyo Co., Ltd., titanium dioxide aqueous dispersion (primary particle size 5 nm, secondary particle size 40-50 nm, solid content concentration 30.1 mass%, specific gravity 1.322, pH 1.9)
Titania (C): manufactured by Ishihara Sangyo Co., Ltd., titanium dioxide aqueous dispersion (primary particle size 30 nm, solid concentration 39.2 mass%, specific gravity 1.345, pH 8.3)
Silane coupling agent (F): 3,3,3-trifluoropropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM7103, specific gravity 1.14)

Ammonia ethanol solution (T): A mixed solution of ammonia aqueous solution having a concentration of 28% by mass and ethanol in a volume of 1: 1 (specific gravity 0.934)
Photoinitiator (U): IC184 (product name, manufactured by BASF)
Barium _{hydroxide: Ba (OH) 2 · 8H} 2 O
Strontium hydroxide: Sr (OH) ₂ · 8H ₂ O
Calcium hydroxide: Ca (OH) ₂
Lead hydroxide: Pb (OH) ₂
Zirconyl nitrate: Zirconium nitrate oxide dihydrate MIBK: Methyl isobutyl ketone (specific gravity 0.8)
MW: Microwave reactor. Product name: Start SYNTH, maximum output: 1000 W, manufactured by I Milestone General Co., Ltd. was used.

[Example 1]
3 ml of titania (A) (TiO ₂ weight: 498 mg) was taken, 5 ml of ethanol was added and stirred, and 275 μl of silane coupling agent (F) was further added and stirred. After the hydrolysis time was 16 hours, 15 ml of ethanol was added, and then the solvent was distilled off at 40 ° C. and 50 hPa. 15 ml of ethanol was added again, and the solvent was distilled off at 40 ° C. and 20 hPa to dryness. Thereto, 5 ml of MIBK was added and dissolved to obtain a titania organic solvent dispersion (V-1). To this titania organic solvent dispersion (V-1), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was put together with 1967 mg of barium hydroxide, 7.5 ml of water, 7.5 ml of ethanol and 15 ml of MIBK in a microwave reaction vessel (hereinafter referred to as MW vessel) having an internal volume of 50 ml. The molar ratio of Ba to Ti (Ba / Ti) in the reaction solution in the MW container is 1/1.
The temperature of the reaction solution in the MW container reaches from room temperature to 165 ° C. in 2 minutes, and from there, microwave (MW) is irradiated so as to maintain the temperature for 10 minutes. W-1) was obtained.
The MW-treated solution (W-1) was allowed to stand to wait for phase separation, and then centrifuged at 480 G for 10 minutes to separate into an aqueous phase (lower phase) and an oil phase (upper phase). This oil phase was dried with an evaporator, and the obtained dried powder was again dissolved and dispersed in 5 ml of MIBK, and purified by centrifugation to remove coarse particles and the like. Thereafter, drying was performed to obtain 1200 mg of the hydrophobic composite metal oxide particles (X-1) before washing.
1200 mg / {titania 498 mg + silane coupling agent 274 μL × specific gravity 1.14 × reduced weight loss 0.79 + barium hydroxide octahydrate 1967 mg × Ba molecular weight (= 137.33) / Ba (OH) _2. The yield calculated from the molecular weight of 8H ₂ O (= 315.46)} (hereinafter the same) was 75%.

About the hydrophobic composite metal oxide particles (X-1) obtained above, in the range of 2θ: 20 ° to 60 ° by an X-ray diffractometer (manufactured by Rigaku Corporation, product name: TTR-III, the same shall apply hereinafter). X-ray diffraction analysis was performed.
As a result, the X-ray diffraction chart contained a peak pattern of barium titanate, and a peak around 25 ° derived from titanium dioxide was not confirmed. This indicates that a composite metal oxide having a perovskite crystal structure composed of barium, titanium, and oxygen was produced.

In this example, since the molar ratio of Ba to Ti (Ba / Ti) in the reaction liquid in the MW container is 1/1, the hydrophobized composite metal oxide particles (X-1) obtained above are treated with an acidic aqueous solution. Washed with.
That is, hydrophobized composite metal oxide particles (X-1) were dissolved in 5 ml of MIBK, washed 3 times with 5 ml of 10% strength acetic acid aqueous solution, further precipitated with hexane, and the precipitate was dried under reduced pressure. 1120 mg of hydrophobized composite metal oxide particles (X-1 ′) was obtained.

<Evaluation>
About the obtained hydrophobic composite metal oxide particles, the following characteristic values (1) to (4) were determined, and the following (5) and (6) were evaluated.
(1) Table 1 shows representative composition formulas and crystal lattice sizes d (nm) of the hydrophobized composite metal oxide particles (X-1 ′) obtained in this example. (The same applies hereinafter.)
As the crystal lattice size d, the plane spacing obtained from the peak appearance position (2θ) in the X-ray diffraction analysis was regarded as the crystal lattice size.
(2) Particle size (2r)
The hydrophobized composite metal oxide particles (X-1 ′) were observed with a transmission electron microscope to determine the particle size (2r). The results are shown in Table 1 (the same applies hereinafter).
An example of imaging of the hydrophobized composite metal oxide particles (X-1 ′) is shown in FIG.
(3) The value of {r ³ + (r−d) ³ } / (2 · r ³ ) was calculated using the above d and r. The results are shown in Table 1 (the same applies hereinafter).
(4) Elemental analysis Elemental analysis was performed on the hydrophobized composite metal oxide particles (X-1 ′) by the following method. The molar ratio k of element A / element B was calculated. The results are shown in Table 1 (the same applies hereinafter).
[Elemental analysis method]
Quantification was performed by ICP emission analysis using a CCD multi-element simultaneous type ICP emission photometric analyzer (SII, model SPS5520). For sample pretreatment, 5 ml of concentrated nitric acid and 0.05 ml of dilute hydrofluoric acid were added per 50 mg of sample and decomposed by ultrasonic waves.

(5) Evaluation of dispersibility in hydrophobic organic solvent Hydrophobized composite metal oxide particles (X-1 ′) were dispersed in a 2: 1 mixed solvent of MIBK and hexane at a concentration of 1% by mass and dispersed. The transmittance at a wavelength of 550 nm was measured at an optical path length of 1 cm before and after dispersion. When the transmittance before dispersion is 1 (reference), the relative value of the transmittance after dispersion is 0.8 or more, Δ when 0.5 or more and less than 0.8, and. When it was less than 5, it was set as x. The results are shown in Table 1 (the same applies hereinafter).
(6) Evaluation of chemical stability 100 mg of each hydrophobized composite metal oxide particle was washed with 5 ml of 10% strength by weight acetic acid aqueous solution three times, and further precipitated with hexane, and the precipitate was dried under reduced pressure. Acid washed. Before and after the acid cleaning, X-ray diffraction analysis was performed in the range of 2θ: 20 ° to 60 ° with the X-ray diffractometer. With respect to the peak pattern of the representative composition formula, the change in peak intensity (half-value width) before and after acid cleaning was examined.
When the peak area before acid cleaning is 1 (reference), the relative value of peak intensity (half width) after cleaning is. ◯ when less than 2, △ when more than 1.2 and less than 1.5, or more than 2 or when no peak was observed (the half width increased as the crystal structure collapsed, peak Becomes broad.) The results are shown in Table 1 (the same applies hereinafter).
In this example, the peak intensity (half-value width) of the hydrophobic composite metal oxide particles (X-1) before washing and the peak intensity of the hydrophobic composite metal oxide particles (X-1 ′) after washing. (Half-width at half maximum) was evaluated by the above method.

[Example 2]
In the same manner as in Example 1, a titania organic solvent dispersion (V-1) was obtained.
To this titania organic solvent dispersion (V-1), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was put into a MW container together with 1642 mg of barium hydroxide, 7.5 ml of water, 7.5 ml of ethanol, and 15 ml of MIBK. The molar ratio of Ba to Ti (Ba / Ti) in the reaction solution in the MW container is 0.835 / 1.
The temperature of the reaction liquid in the MW container reached from the room temperature to 165 ° C. in 2 minutes, from which it was irradiated with microwaves so as to hold it for 10 minutes, then naturally cooled, and the MW-treated solution (W-2) Got.
The MW-treated solution (W-2) was treated in the same manner as in Example 1 to obtain 1200 mg of the hydrophobic composite metal oxide particles (X-2). The yield was 82%.
The obtained hydrophobic composite metal oxide particles (X-2) were evaluated in the same manner as in Example 1.

[Example 3]
In the same manner as in Example 1, a titania organic solvent dispersion (V-1) was obtained.
To this titania organic solvent dispersion (V-1), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was placed in an MW container together with 1384 mg of strontium hydroxide, 7.5 ml of water, 7.5 ml of ethanol, and 15 ml of MIBK. The molar ratio of Sr to Ti (Sr / Ti) in the reaction solution in the MW container is 0.835 / 1.
The temperature of the reaction liquid in the MW container reached from the room temperature to 165 ° C. in 2 minutes, and then irradiated with microwaves so as to hold it for 16 minutes, and then naturally cooled, MW-treated solution (W-3) Got.
The MW-treated solution (W-3) was treated in the same manner as in Example 2 to obtain 1000 mg of the hydrophobic composite metal oxide particles (X-3). The yield was 83%.
The obtained hydrophobic composite metal oxide particles (X-3) were evaluated in the same manner as in Example 1.

[Example 4]
In the same manner as in Example 1, a titania organic solvent dispersion (V-1) was obtained.
To this titania organic solvent dispersion (V-1), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was put into a MW container together with 985 mg of barium hydroxide, 553 mg of strontium hydroxide, 7.5 ml of water, 7.5 ml of ethanol and 15 ml of MIBK. The total molar ratio of Ba and Sr to Ti ((Ba + Sr) / Ti) in the reaction solution in the MW container is 0.835 / 1. The molar ratio Ba / Sr is 7/3.
The temperature in the MW container reached from the room temperature to 165 ° C. in 2 minutes, from which irradiation with microwaves was performed for 12 minutes, followed by natural cooling to obtain a MW-treated solution (W-4).
The MW-treated solution (W-4) was treated in the same manner as in Example 2 to obtain 1100 mg of the hydrophobic composite metal oxide particles (X-4). The yield was 81%.
The obtained hydrophobic composite metal oxide particles (X-4) were evaluated in the same manner as in Example 1.

[Example 5]
In the same manner as in Example 1, a titania organic solvent dispersion (V-1) was obtained.
To this titania organic solvent dispersion (V-1), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was put into a MW container together with 386 mg of calcium hydroxide, 24 mg of barium hydroxide, 7.5 ml of water, 7.5 ml of ethanol and 15 ml of MIBK. The molar ratio of Ca to Ti (Ca / Ti) in the reaction solution in the MW container is 0.85 / 1.
The temperature of the reaction solution in the MW container reached from room temperature to 165 ° C. in 2 minutes, and then irradiated with microwaves to hold it for 30 minutes, then cooled naturally, and the MW-treated solution (W-5) was Obtained.
The MW-treated solution (W-5) was treated in the same manner as in Example 2 to obtain 830 mg of the hydrophobic composite metal oxide particles (X-5). The yield was 85%.
The obtained hydrophobic composite metal oxide particles (X-5) were evaluated in the same manner as in Example 1.

[Example 6]
A titania organic solvent dispersion (V-6) was prepared in the same manner as in Example 1 except that 2.25 ml of titania (A) (TiO ₂ weight: 374 mg) and 280 μl of the silane coupling agent (F) were taken. Obtained.
To this titania organic solvent dispersion (V-6), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was put into a MW container together with 1642 mg of barium hydroxide, 417 mg of zirconium nitrate, 7.5 ml of water, 7.5 ml of ethanol, and 15 ml of MIBK. The molar ratio of Ba to the total of Ti and Zr in the reaction solution in the MW container (Ba / (Ti + Zr)) is 0.835 / 1. The molar ratio of Ti / Zr is 75/25.
The temperature of the reaction solution in the MW container reached from room temperature to 165 ° C. in 2 minutes, and then irradiated with microwave (MW) to hold it for 10 minutes, and then naturally cooled, and the MW-treated solution (W− 6) was obtained.
The MW-treated solution (W-6) was treated in the same manner as in Example 2 to obtain 1250 mg of hydrophobized composite metal oxide particles (X-6). The yield was 84%.
The obtained hydrophobic composite metal oxide particles (X-6) were evaluated in the same manner as in Example 1.

[Example 7]
A titania organic solvent dispersion (V-7) was prepared in the same manner as in Example 1 except that 1.425 ml of titania (A) (TiO ₂ weight: 237 mg) and 290 μl of the silane coupling agent (F) were taken. Obtained.
To this titania organic solvent dispersion (V-7), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was put in an MW container together with 2418 mg of lead hydroxide, 875 mg of zirconium nitrate, 7.5 ml of water, 7.5 ml of ethanol, and 15 ml of MIBK. The molar ratio of Pb to the sum of Ti and Zr in the reaction solution in the MW container (Pb / (Ti + Zr)) is 0.835 / 1. The molar ratio of Ti / Zr is 475/525.
The temperature of the reaction solution in the MW container reached from room temperature to 165 ° C. in 2 minutes, and then irradiated with microwave (MW) to hold it for 20 minutes, then naturally cooled, and the MW-treated solution (W− 7) was obtained.
The MW-treated solution (W-7) was treated in the same manner as in Example 2 to obtain 1300 mg of the hydrophobized composite metal oxide particles (X-7). The yield was 69%.
The obtained hydrophobic composite metal oxide particles (X-7) were evaluated in the same manner as in Example 1.

[Example 8]
A titania organic solvent dispersion (V-8) was prepared in the same manner as in Example 1 except that 2.7 ml of titania (A) (TiO ₂ weight: 448 mg) and 280 μl of silane coupling agent (F) were taken. Obtained.
To this titania organic solvent dispersion (V-8), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was put in an MW container together with 1396 mg of barium hydroxide, 58 mg of calcium hydroxide, 167 mg of zirconium nitrate, 7.5 ml of water, 7.5 ml of ethanol and 15 ml of MIBK. The molar ratio of Ba and Ca ((Ba + Ca) / (Ti + Zr)) to the total of Ti and Zr in the reaction solution in the MW container is 0.835 / 1. The molar ratio of Ba / Ca is 85/15, and the molar ratio of Ti / Zr is 90/10.
The temperature of the reaction solution in the MW container reached from the room temperature to 165 ° C. in 2 minutes, and then irradiated with microwave (MW) to hold it for 12 minutes, and then naturally cooled, and the MW-treated solution (W− 8) was obtained.
The MW-treated solution (W-8) was treated in the same manner as in Example 2 to obtain 1250 mg of hydrophobic composite metal oxide particles (X-8). The yield was 90%.
The obtained hydrophobic composite metal oxide particles (X-8) were evaluated in the same manner as in Example 1.

[Example 9]
In the same manner as in Example 1 except that titania (B) was used instead of titania (A) and 195 μl of silane coupling agent (F) was taken in Example 1, titania organic solvent dispersion (V-9) Got.
This titania organic solvent dispersion (V-9) was treated in the same manner as in Example 2 except that 1926 mg of barium hydroxide was taken to obtain a MW-treated solution (W-9). The molar ratio of Ba to Ti (element Ba / Ti) in the reaction solution is 0.979 / 1.
This MW-treated solution (W-9) was treated in the same manner as in Example 2 to obtain 1200 mg of the hydrophobic composite metal oxide particles (X-9). The yield was 79%.
The obtained hydrophobic composite metal oxide particles (X-9) were evaluated in the same manner as in Example 1.
An example of imaging of the hydrophobized composite metal oxide particles (X-9) obtained in this example is shown in FIG.

[Example 10]
In Example 1, titania (C) was used instead of titania (A), and 50 μl of silane coupling agent (F) was used. In the same manner as in Example 1, titania organic solvent dispersion (V-10) Got.
This titania organic solvent dispersion (V-10) was treated in the same manner as in Example 2 except that 1905 mg of barium hydroxide was taken to obtain a MW-treated solution (W-10). The molar ratio of Ba to Ti (element Ba / Ti) in the reaction solution is 0.97 / 1.
This MW-treated solution (W-10) was treated in the same manner as in Example 2 to obtain 1200 mg of hydrophobic composite metal oxide particles (X-10). The yield was 87%.
The obtained hydrophobic composite metal oxide particles (X-10) were evaluated in the same manner as in Example 1.
An example of imaging of the hydrophobized composite metal oxide particles (X-10) obtained in this example is shown in FIG.

[Example 11]
In the same manner as in Example 1, a titania organic solvent dispersion (V-1) was obtained.
To this titania organic solvent dispersion (V-1), 5 ml of ammonia ethanol solution (T) was added and stirred well to adjust the pH to about 11-12. This was put into a MW container together with 1042 mg of barium hydroxide, 7.5 ml of water, 7.5 ml of ethanol, and 15 ml of MIBK. The molar ratio of Ba to Ti (Ba / Ti) in the reaction solution in the MW container is 0.53 / 1.
The temperature of the reaction solution in the MW container reached from the room temperature to 165 ° C. in 2 minutes, and then irradiated with microwaves so as to hold it for 10 minutes, and then naturally cooled, and the solution treated with MW (W-11) Got.
The MW-treated solution (W-11) was treated in the same manner as in Example 1 to obtain 960 mg of the hydrophobized composite metal oxide particles (X-11). The yield was 80%.
The obtained hydrophobic composite metal oxide particles (X-11) were evaluated in the same manner as in Example 1.

[Comparative Example 1]
In this example, barium titanate particles were produced by a hydrothermal method.
0.5 ml of titania (A) (TiO ₂ weight: 83 mg) was taken and diluted by adding 39.5 ml of water. This was placed in a MW container along with 328 mg of barium hydroxide. The molar ratio of Ba to Ti (Ba / Ti) in the reaction solution in the MW container is 1/1.
The temperature of the reaction liquid in the MW container reaches from room temperature to 165 ° C. in 2 minutes, from which it is irradiated with microwaves to hold it for 10 minutes, and then naturally cooled, and the MW-treated solution (W-21) is Obtained.
In this MW-treated solution (W-21), a white solid was precipitated and was not dispersed. This white solid was dried to obtain barium titanate particles (X-21).

<Evaluation>
The barium titanate particles (X-21) were observed with a transmission electron microscope and the particle size (2r) was determined to be 80 to 100 nm. An example of imaging of barium titanate particles (X-21) is shown in FIG.
When elemental analysis was performed on the barium titanate particles (X-21) in the same manner as in Example 1, the molar ratio k of element A / element B (Ba / Ti) was 0.99.
Since the particle size of the barium titanate particles (X-21) was too large, the particles were pulverized for 3 days with a ball mill in order to disperse them in an organic solvent after being pulverized and treated with a silane coupling agent. At this time, in order to promote the opening of the particles, the particles were suspended in 10 ml of a 2% strength by weight acetic acid aqueous solution and pulverized. When the suspension after the pulverization treatment was dried and X-ray diffraction analysis was performed in the range of 2θ: 20 ° to 60 ° with the X-ray diffractometer, the peak pattern of barium titanate was not observed. That is, the crystal structure of barium titanate was not maintained in the acid treatment.

Claims (3)

A composite metal oxide particle comprising a composite metal oxide, wherein the composite metal oxide comprises at least one element selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Sn. And a composite metal oxide comprising one or more elements B selected from the group consisting of Ti, Zr, W, Nb, Hf, Sn, and Si and oxygen O as constituent elements,
The composite metal oxide particles have a particle size (2r) by transmission microscope observation of 1 to 70 nm,
A mixed metal oxide particle, wherein the molar ratio k of element A / element B satisfies the following formulas (I) to (III):
{R ³ + (r−d) ³ } / (2 · r ³ ) −0.3 ≦ k (I)
k ≦ {r ³ + (r−d) ³ } / (2 · r ³ ) +0.1 (II)
k <0.98 (III)
(In the formula, r is a half value (unit: nm) of the particle size (2r), and d is the crystal lattice size (unit: nm) of the composite metal oxide.)   The composite according to claim 1, further comprising one or more silane coupling agent-derived components selected from the group consisting of a silane coupling agent, a hydrolyzate of the silane coupling agent, and a hydrolysis condensate of the silane coupling agent. Metal oxide particles.   A composition comprising the composite metal oxide particles according to claim 2 and an organic medium.